Botany - Paper II - For Class XII (Science Group) - Solved Model papers 2020 -2021

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Botany - Paper II
For Class XII (Science Group)
Solved Model papers 2020 -2021

Time: 01 hour   Marks: 20

SECTION 'B' (SHORT-ANSWER QUESTIONS) (Marks: 12)

Q.2: Attempt any Four-part questions. Each question carries one mark. Give answer not more than two lines.
(i) Name the pyrimidine bases in DNA structure.
Ans: Pyrimidine bases in DNA structure are:

• Cytosine
• Thymine

(ii) Define Apomixis and Parthenocarpy?
Ans: Definition Of Apomixis:
It is a modified form of asexual reproduction and naturally occurs in some plants. The production of embryo or seeds without meiosis and fertilization of flower is called Apomixis. Those plants which are produced by Apomixis are called "Apomicts".
Example: Asexual reproduction in Dandelions plant.

Definition Of Parthenocarpy:
In some plants fruits formation takes place without the process of fertilization and pollination, such fruits are always seedless and described as parthenocarpic fruit ( Parthenos = virgin, carpic = pertaining to fruit). This type of process is called as parthenocarpy.
Example: Banana, pine-apple, some grapes and orange varieties etc.

(iii) Define any one of the followings: (a) Autosome (b) Sex chromosomes
Ans: (a) Autosome:
The chromosomes which are similar in males and females are called autosomes.

(b) Sex chromosomes:
Those chromosomes which are involved in the determination of sex of the individual are called sex chromosomes.

(iv) Name the types of RNA involved in protein biosynthesis.
Ans: RNA involved in protein biosynthesis:
There are three major classes of RNA involved in protein biosynthesis, which are:

1. Ribosomal RNA (rRNA)
2. Transfer RNA (tRNA)
3. Messenger RNA (mRNA)

(v) What happens when a cell is placed in a hypotonic solution?
Ans: If a plant cell is placed in hypotonic solution ( pure water or solution of higher water potential than the solution in its vacuole), the water moves from outside to inside the cell (endosmosis) and ultimately into the vacuole. As a result the cell swells or become turgid, Further allowing the cell into such hypotonic medium does not cause it to burst because the cell wall develop a tension causing an internal hydrostatic pressure or pressure potential due to which further uptake of water in cytoplasm is resisted and finally stop.

(vi) Write number of chromosomes in Pea (Pisum sativum) and Sugarcane (Saccharum officinarum)?
Ans: Number Of Chromosomes In:

• Pea (Pisum sativum): 14 Chromosomes or 7 Pairs
• Sugarcane (Saccharum officinarum): 80 Chromosomes or 40 Pairs

(vii) Define meristematic tissues and name its types.
Ans: Meristematic Tissues:
These tissues are composed of cells, which have the ability to divide. The cells are thin walled, have large nucleus and number of small vacuoles. Usually they do not have inter-cellular spaces, so the cells are arranged compactly. Two main types of meristematic tissues are recognized in plants.

• Apical meristems
• Lateral meristems

OR

(vii) How young stem gives mechanical support to plant body
Ans: Young stem has special type of anatomical arrangement, which also helps in supporting plant. The outermost layer of thin walled cells called epidermis. Region beneath epidermis are called cortex and the central portion called stele, which is mainly consist of vascular tissues and some soft tissues. This type of stem depends for its mechanical support on following tissues:

• Thin walled parenchyma - having turgidity.
• Thick walled living tissues like collenchyma and  sclerenchyma.
• Stele as cylindrical core of vascular bundles.

Q3. Attempt any Four-part questions. Each question carries Two marks. Give answer not more than five lines.
(i) What is the phenotypic ratio if cross between color blind male and carrier female, with the help of checker board.
Ans: Cross between color blind male and carrier female:

(ii) Describe the changes occurs in Prophase of Mitosis.
Ans: Prophase Of Mitosis:

• This is the main and longest phase of nuclear division. The following main changes occur in nucleus and cytoplasm of a cell:
• During early prophase chromtin network breaks up to form long coiled, thick thread like structure called chromosomes.
• Each chromosome at this stage is already double, shorten and thicken in a pair of fine threads called chromatid.
• The nuclear membrane gradually disappears and spindle fibres are formed.
• At the same time centrosome divides to form two centrioles, each moves towards the opposite pole of the animal cell. The centrioles are absent in plant cells.

(iii) Describe any one of the followings:
Ans: Definitions:
(a) Pollination:
Pollination is a process in which pollen grains released from from anther (stamen) and carried by wind or animals land on the sticky stigma (carpel) though not necessarily on the same flower or plant.

(b) Double fertilization:
The union of two sperm cells with different cells of the embryo sac is termed as double fertilization. double fertilization ensure that the endosperm will develop only in ovules where the egg has been fertilized, thereby preventing angiosperms from squandering nutrients.

(iv) Name only the Biotic components of an ecosystem.
Ans: Biotic Components Of An Ecosystem Are:

• Producers
• Consumers
• Decomposers

(v) How is Photonasty different from Phototropism?
Ans: Difference between Photonasty and Phototropism

Photonasty	Phototropism
It is non- directional movement caused by stimulus of light	(photo = light, tropos = turn). It is a irectional movement that takes place when plant is exposed to light coming only one directio.
The flower open or close due to light intensity.	It is positive if the movement is towards the source of light and if curvature (direction of) movement away from the source of light, it is negative phototropism
e.g: The flower ofoxalis and portulaca open in day and close at night.	e.g: stem grows towards source of light (positive phototropism) while roots grow away from source of light (negative phototropism)

(vi) State the law of Segregation.
Ans: Law Of Segregation:
Mendels's law of segregation states that
"Each organism contains 2 factors for each traits and these factors segregate during the formation of gametes so that each gamete contains only one factor for each trait. When fertilization occurs, the new organism receives 2 factors for each traits, one from each parents."

(vii) Define Nastic movement.
Ans: Nastic Movement (Non-directional movement):
The term nastic movement is used for the movement which is unrelated to direction of stimuli and direction of stimulus is not fixed. This type of movement is mostly observed in leaves and petals etc. The types of nastic movement depend on the type of stimulus, they may be:

• Photonastic
• Thermonastic
• Seismonastic
• Nyctinastic
• Hyponastic

(viii) Discuss Abiotic components of desert ecosystem
Ans: Abiotic Components Of Desert Ecosystem:

• Dry climate
• Sunlight
• Hot sand
• The lack of moisture and water
• Hot temperature

SECTION 'C' (DETAILED-ANSWER QUESTIONS)
(Max-Marks: 08)

Note: Attempt any Two questions from this section. All questions carry equal marks. (Diagram is not required)

Q.4: Explain the climatic factors of an ecosystem.
Ans: CLIMATIC FACTORS OF AN ECOSYSTEM:
It consists of::

1. LIGHT
2. TEMPERATURE
3. WATER
4. ATMOSPHERE AND WIND
5. FIRE

1. LIGHT:

• Light is an important factor of life.
• The main source of light ss the sun.
• Light is essential for green plants for photosynthesis.
• Only 3% of total sunlight, which fulls on earth, is utilized.
• The intensity, duration and quality of light is important for living organisms.

i) LIGHT INTENSITY:

• Light intensity varies with seasons by light intensity.
• Opening and closing of stomata and permeability of cell membrane is affected by light intensity.
• Intense light destroys chlorophyll.
• The plants growing In light arc called helophytes while those growing in shade are called sclophytes.

ii) LIGHT DURATION:

• The light duration or photoperiod has marked-effect on flowering, leaf fall and dormancy in plants.
• In animals, behavioral activities (biological rhythms) such as court ship display, nesting and other behaviours are also effected by light.
• In spring, migration of certain groups of birds depend upon photoperiod.

iii) LIGHT QUANTITY:

• The visible light which ranges from 400-780 mn, consists of seven colours. The chlorophyll absorbs red and blue green colour for photosynthesis.
• Light with shorter wavelength carries more energy but destroys micro-organisms and also causes sunburn in human beings.

2. TEMPERATURE:

• A moderate temperature favours the growth and other activities of plants and animals.
• Life exists, from 0°C to 50°C.
• Different animals found at different places are due to variation in temperature.
• Temperature below freezing. point or high temperature kills the living organisms or damage them.
• Optimum temperature is required for enzymes efficiency.

3. WATER:

• Water is the most important factor of ecosystem and is an important need of all the living organisms.
• According to the availability of water, plants are grouped into XEROPHYTES, HYDROPHYTES and MESOPHYTES.
• Water is abundant in aquatic ecosystem while it becomes limited in terrestrial ecosystem.
• Water Is needed for all the physiological activities of plants and animals.
• It is one of the raw materials needed for photosynthesis.
• In terrestrial ecosystem, rainfall is the main source of water.
• Plants absorb it from soil, however its availability is related to many factor like edaphic factors of soil and kind of vegetation.
• In nature continuous cycling of water also takes place, it is culled hydrological cycle.

4. ATMOSPHERE AND WIND:

• Atmosphere is u store house of CO₂, O₂, N₂ and vapours of water.
• O₂ is used In respiration.
• CO₂ in used in photosynthesis and N₂ is a major component of protein.
• Wind current distributes these gases and brings atmospheric circulation of water vapours.
• Wind also favour pollination and dispersal of seeds.
• Wind with high velocity breaks the branches and plants.
• Wind also influences the migration of flying birds and restricts timberline.
• At high altitude the air pressure and percentage of oxygen is low that's why in these areas mammals cannot live.

5. FIRE:

• Fire is n physical factor, which brings a sudden change in ecosystem.
• A Fire may be caused by lightening, volcanic activities rind mutual friction between trees such as bamboos and mostly by man.
• A forest which is established and created in centuries is destroyed in few minutes by fire.
• Fire favour the competition among trees and set new species as climax.
• Fire recycles various nutrients and new growth is stimulated.
• Fire also favours the growth of some fungi. These fungi are called Pyrophilous Fungi.
• Pyrophilous fungi decompose unborn dead plants or animals.
• Men made fires are set to clear ground for agriculture or making mud but this is the destruction of ecosystem.

OR

Describe osmoregulation in flowering plants?
Osmoregulatlon in Plants:
Efficient functioning of the plant cells and the whole plant depends upon maintaining the water content at a steady state. According to the availability of water, the pIants are divided into four groups.

• Hydrophytes
• Mesophytes
• Xerophytes
• Halophytes

Hydrophytes:
Hydrophytes are those plants, which are found in fresh water habitat.
The plants may be partly or totally submerged in water. They do not have any difficulty in obtaining water, To remove excessive water, they have following adaptation's.

Adaptations to remove extra water:

• Their leaves are large so surface area is large for removal of excessive water by transpiration.
• They have large number of stomata at upper surface of leaves.
• Stem and leaves are without cuticle.
• The Stomata always remain open.
• Root is absent, if present root hairs are absent.

Mesophytes:

• These are those plants, which are found in moderate supply or water, majority of angiosperms are mesophytes. These are the land plants and can easily maintain their water balance.
• When there Is sufficient supply of water, the stomata are kept open but when there is restricted supply, the stomata are closed.
• To prevent excessive loss, the stems and leave are covered with cuticle.
• Shape of leaf is variable which also helps in regulating water. Leaf fall also help in regulating water.

Xerophytes:

• These are the plants which are found in dry places such as deserts, steep hills. Under such conditions, the water potential is very low. They have following adaptations to prevent the water loss.
• Root is deep vertical to absorb more water from soil and it also spread horizontally.
• Leave in most cases are absent or shed during dry season. In such cases stem becomes green and perform the function of photosynthesis.
• Leaves become small or modified into spines to reduced the rate of transpiration.
• The leaves are covered with cuticle (thick waxy layer) or by hair.
• Number of stomata are reduced and are sunken type.
• In rainy season stem, root and leaves store water in their parenchymatous cells such plants are called succulents.
• Leaves fold themselves to reduce the rate of transpiration.
• Germination of seed occurs during rainy season.

Halophytes:

• The plants growing in salt marshes close to sea are called halophytes. They have to absorb water, which has high salt concentration, i.e. with lower water potential.
• Such plant actively absorbs salt by their root and as the salt concentration in their root cell becomes high, they absorb water by osmosis.
• Excess of salt absorbed by root, stored in the cells is excreted out from salt glands in leaves.
• The salt thus secreted by some species help them to trap wow vapours from air, which is being absorbed in liquid form by leave surface.

Q.5: Define Meiosis. Explain the various stages of Prophase -I of meiosis.
Ans: MEIOSIS:
Meiosis is a cell division in which one cell divides into four cells and the number of the chromosomes is reduced to half. Meiosis occurs in diploid cells during gametogenesis. Meiosis consists of two successive divisions, Division I and Division II.
Division I is reduction division, during which the chromosomes number (2n) in both daughter cells is reduced to half (n).
Division II is simple mitotic in nature.
Each division passes through four phases, as:

1^st Meiotic Division

1. Prophase I
2. Metaphase I
3. Anaphase I
4. Telophase I

2^nd Meiotic Division

1. Prophase II
2. Metaphase II
3. Anaphase II
4. Telophase II

PROPHASE I:
Prophase of first meiotic division is longer in duration and complicated. It passes through five sub-stages.

1. Leptotene
2. Zygotene
3. Pachytene
4. Diplotene
5. Diakinesis

Leptotene = (Slender):

• This is the first stage of meiosis.
• The chromatin material condenses to from thread like structures called chromosomes.
• Before meiosis starts, the chromosomes become duplicated which is DNA replication, but the two chromosomes are so close that they look like a thread.
• The identical pairs, Maternal and Paternal chromosomes remain unevenly distributed.
• The centrioles move to the opposite poles.

Zygotene = (Joining):

• The chromosomes shorten and thicken.
• The homologous (maternal and paternal) chromosomes attracts each other and start pairing, the process is called SYNAPSIS.
• The pairing is very exact and is point to point and gene to gene.
• The two synapped chromosomes are called BIVALENTS.

Pachytene = (Thick):

• After pairing, the chromosomes become thick and short.
• The homologous chromosomes twine around each other and each starts splitting into two sister chromatids by a longitudinal splitting except in the centromere region.
• Due to this splitting, the bivalent becomes tetravalent (with four chromatids).

Diplotene = (Double):

• The synaptic force of attraction between each bivalent consisting of four chromatids decrease.
• The homologous chromosomes start repelling each other but mostly uncoiled i.e. overlapping areas remain contact in one or more points.
• This point of contact is called chiasma (Plural: Chiasmata).
• The overlapping occurs at non-sister chromatids.
• At chiasmata the chromatids breaks. This breakage is accompanied by reunion in such a way that corresponding fragments are interchanged between the two non-homologous chromosomes, this physical change is called crossing over.
• Crossing over is significant in heredity.

Diakinesis = (Through movement):

• Diakinesis is characterized by the disappearing of the nuclear membrane, nucleolus and completion of spindle apparatus.
• The separation of bivalent is completed by the process called terminalization.
• The movement of the chiasmata from the centromere towards the ends of the chromosome arms take place like a zipper.
• At the end of stage, the two chromatids held together at their ends and the bivalent become more thickened, contracted and prominently visible.

Q. No.6: Define "Law of Independent assortment" and explain with checkerboard.
Ans: Statement Of Mendel's Second Principle (Law of Independent Assortment):
Gregor John Mendel's proposed the Law of Independent Assortment, which state that:

"The memberof one pair of genes segregate independently of the other pairs."

OR

"Members of one pair of factor segregate (assort) independently of members of another pair of factor. Therefore all possible combinations of factors can occur in gametes."

OR

"When a pair or contrasting characters are followed in one cross, their genes assort independently into gametes, gave of one pair inherit independently of the other pair, therefore all possible combinations of genes can occur in gametes."

Mendel's Procedure:
After working on several monobybrid crosses, Mendel took two traits for cross between two individuals. Such cross is called dihybrid cross, and the ratio obtained in F₂ generation is called dihybrid ratio. The result achieved as a consequence of dihybrid-cross is spoken of as Inheritance of two traits.
Mendel experiments on garden peas. He took 4 units of characters such as;

1. Yellow Flower (YY) with round seeds (RR)
2. Green Flower (yy) with wrinkled seeds (rr).

The cross was made between true breeder parents.
F₁ generation produced all flower yellow with round seed as both the traits were dominant.
But when seeds of F₁ generation were collected and sown, the segregation of characters took all possible combinations and produced 4 kinds or offspring in F₂ in the following ratio:-

9 Yellow round.

3 Yellow wrinkled.

3 Green round.

1 Green wrinkled.

i.e. 9 : 3 ; 3 : 1.

It has also been noticed that some of them were homozygous and some were heterozygous.
Among the 4 kinds of offspring, two showed parental combination (Yellow round and green wrinkled) while two were new i.e. Green round and Yellow wrinkled. This means that trait of round seed was not tied with yellow colour and it was inherited independently. This exchange of genes (trait) takes place during crossing over which provides an opportunity for new varieties.

Result:- Thus we obtained a ratio 9 : 3 : 3 : 1

Q.No.7: Explain ultrastructure of Chromosomes.
Ans: Ultrastucture of Chromosomes:
The chromosome of a eukaryotic cell has 40%. DNA and 60% protein. A significant amount of RNA is also associated with chromosome because DNA is responsible for RNA formation. The DNA of a chromosomes is very, long double stranded fiber that stands, a duplex which extends unbroken through the entire length of chromosome.
A typical human chromosome has 140 million nucleotide in its DNA. The amount of information Coded in one chromosome fills about 280 books of 1000 pages. If a strand of a chromosome is laid in straight line, it would be 5 cm long.
Under electron microscope DNA of a eukaryotic cell show following Ultrastucture of Chromosomes:

Nucleosome:
The coiling of DNA is like string of beads. DNA duplex is coiled around a complex histone, which are small, very basic polypeptides, rich in the amino acids, arginine and lysine. Eight of these histone form the core of an assembly called a 'NUCLEOSOME'. Because so many of their amino acids are basic histones are very positively charged. The DNA duplex, which is negatively charged, is strongly attracted to histone and wraps tightly around the histone core of each nucleosome. The core thus acts as a magnetic forms that promotes and guides the coiling or DNA. Nucleoprotein (histone) gives DNA fiber as a beaded structure. The nucleosome is repeated after every 200 nucleotides of DNA.

Spacer DNA:
The DNA present from one nueleosome (bend) to an other is called Spacer DNA.

Super Coil:
Further coiling of DNA occurs when the string of nucleosome wraps into higher-order coils called Super Coil.

Chromatin:
The super coil network is called chromatin (Chromatin network) Chromatin is a loose network of threads which is seen in non living nucleus. Chromatin is again classified into Euchromatin and heterpchromatin on the basis of staining properties.

Heterochromatin:
Stains deeply because it is more coiled and compact it is inactive and never expressed itself.

Euchromatin:
Stains more during nuclear division and is involved in transcription (Protein Synthesis).

Q.No7: What do you mean by sex determination? Discuss linked inheritance with reference to colour blindness.

Ans: SEX CHROMOSOME:
The biologist tried to determine, whether an offspring will be male or female in an egg. The first information on sex came from Cytological studies by C.E. Mc Clung, E.B Wilson and N Steven between 1901-1905.
It was found that in plants and animals most of the chromosomes are pairs of homologous chromosomes, the members of one pair are not homologous, i.e. the two differ from each other morphologically in both male and female.

"This odd chromosome, which determines the sex of the individual is termed as "sex chromosomes".

The sex chromosomes are non-homologous and are mostly represented by 'X' and 'Y' chromosomes and they can not form pair.
For example: In human being, the difference in males and females is not of one whole chromosome, but of the shape of one chromosome in one sex, which is unlike its mate and unlike any chromosome in the opposite sex. In man each sex cell has 46 chromosomes, of which 44 i.e. 22 pairs are similar in both sexes, these are called autosomes. The 23^rd pair in female consists of two similar chromosomes, but in the male of the 23^rd pair differ in shape, one of the two is like those of the female, but the second is much smaller, these are called sex chromosomes. The two chromosomes of the female and one of the male which are alike known as X chromosomes, while the unlike smaller one only in male is called Y chromosome. The human female possesses a genotype of 44 + XX chromosomes, whereas the genotype of male is 44 + XY chromosomes.

Linked Inheritance:
A form of inheritance in which the transmission of the genetic material is coreeelated with the sex of the parents is called sex linked inheritance.

OR

Any genetic trait which is transmitted through sex chromosome is called sex linked inheritance.

Linked Inheritance With Reference To Colour Blindness:
It is a sex-linked inheritance found in human beings. Persons suffering from colour blindness have difficulty in distinguishing red from green. It is a rather common trait and more common in males. It is because Y chromosome is inherit for this trait. Only one gene of this trait will render a colour blind man. While on the other hand a woman must have two genes for this trait to become colour blind. This trait of colour blindness can easily be detected by using special charts made up of a number of coloured dots so arranged that colour blind persons see a different pattern than other persons do.
The possible results of various crosses are shown in the following charts.

Gene on chromosome
N = Normal eyed male
n = Colour blind female

(i) CROSS BETWEEN COLOUR BLIND MALE AND NORMAL FEMALE:

Result: When a colour blind male marries a normal female, all children will be normal but daughters will be colour blind carrier.

SOURCE: Board Of Intermediate Education Karachi

Botany - Paper I - For Class XI (Science Group) - Model papers with Solved MCQs 2020 -2021

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Botany - Paper I
For Class XI (Science Group)
Model papers 2020 -2021

Time: 01 hour     Total Marks: 23

SECTION 'B' (SHORT-ANSWER QUESTIONS) (Marks: 14)

Q.2: Attempt any Six-part questions. Each question carries one mark. Give answer not more than two lines.
(i) Give two difference between Prokaryotes and Eukaryotes.
Ans: DIFFERENCE BETWEEN PROKARYOTES AND EUKARYOTES

	PROKARYOTES	EUKARYOTES
Type of Cell	Always unicellular	Unicellular and multicellular
Cell size	Ranges in size from 0.2 μm 2.0 μm in diameter.	Size ranges from 10 μm 100 μm in diameter.
Cell wall	Usually present chemically complex in nature.	When present chemically simple in nature.
Nucleus	Absent. Instead they have a nucleoid region in the cell.	Present
Ribosomes	Present. Smaller in size and spherical in shape.	Present. Comparatively larger in size and linear in shape.
DNA arrangement	Circular	Linear
Mitochondria	Absent	Present
Cytoplasm	Present. But cell organelles absent.	Present, cell organelles Present.

(Note: write two two differences as mentioned in question)

(ii) Why lysosomes are called suicide sacs?
Ans: Lysosomes are known as suicide bags of the cell because they contain lytic enzymes capable of digesting cells and unwanted materials. Autolysis and burst open, when the cell is damaged. This causes the hydrolytic enzyme to be released. The released enzymes then digest their own cell, causing the cell to die. As a result, they are known as cell suicide bags.

OR

(ii) Name any two diseases caused by Virus.
Ans: Name of plant diseases caused by Virus

• Tobacco mosaic -Virus (TMV)
• Cucumber mosaic -Virus (CMV)
• Tomato spotted wilt-Virus (TSWV)

Name of Animal diseases caused by Virus

• Poliomyelitis
• Colds, Flu
• Dengue and yellow fever
• Aids
• Rabies
• Measles
• Mumps
• Hepatitis

(Note: Any two disease name, better to select plant's viral disease as it is botany section.)

(iii) Define any two of the followings:
♦ Double Fertilization
♦ Homosporous
♦ Diffusion
♦ Pili
Ans: DEFINITION:
a) Double Fertilization:
Double fertilization is a special type of fertilization which occurs only in angiospermic plants. During this process a sperm fuses with the ovum to form oospore. The other sperm fuses with secondary nucleus to form triploid endosperm nucleus.

OR

Double Fertilization is a chief trait of flowering plants. In the phenomena, one female gamete unites with two male gametes. One of the male gametes fertilizes the egg resulting in the formation of a zygote and the other unites with a polar nuclei for the formation of an endosperm.

b) Homosporous:
Plants like Lycopodium, Pteridophytes that produce only one kind of spore, and hence have only one kind of gametophyte that bears both male and female organs (i.e not separated by sex) are said to be homosporous.

OR

(iii) Diffusion:
The movement of molecules from the region of higher concentration to the region of lower concentration is called diffusion. Example: One of the most common example of diffusion is, if a bottle of perfume is opened in a comer of a room, it can be smelt in the entire room after some time.

(iv) Pili:
Pili is found in the bacterial cell. They are generally referred to as the hollow, filamentous appendages, which are involved in the conjugation. They help in conjugation and not in locomotion. They are also known as long conjugative pili. They are smaller than flagella and longer than fimbriae and involved in the cell to cell attachment during conjugation for DNA transfer.

(iv) On what basis Fungi are classified?
Ans: BASIS OF CLASSIFICATION OF FUNGI:
Fungi are usually classified in four divisions:

1. Zygomycota (bread molds)
2. Ascomycota (yeast and sac fungi)
3. Basidiomycota (club fungi)
4. Deuteromycota or Chytridiomycota (chytrids)

These major groups of fungi are distinguishable on the basis of sexual reproduction.

OR

(iv) Write the molecular formula of chlorophyll a and b.
Ans: MOLECULAR FORMULA OF CHLOROPHYLL A and B:
The molecular formula of chlorophyll a is: C₅₅ H₇₂ O₅ N₄ Mg
The molecular formula of chlorophyll Is b is: C₅₅ H₇₀ O₆ N₄ Mg

(v) Why protoctista considered as polyphyletic kingdom?
Ans: Kingdom Protista is considered as polyphyletic group because they have many characters of their ancestors. The word polyphyletic means they do not share a single common ancestor and as protoctists have characters of animals, plants and fungi so that they are regarded as polyphyletic group of organism.

(vi) Why yeast is placed in fungi, while it is unicellular?
Ans: The yeast is placed in fungi because

1. Yeast reproduces sexually with the production of ascospores.
2. The have cell wall made of chitin.
3. They have haploid nuclei.
4. Most of their reproduction is asexual and takes place by cell fission or budding (the formation of a smaller cell from a larger one).

(vii) Name three methods of genetic recombination in Bacteria.
Ans: In bacteria the process of genetic recombination takes place through three process which are following:

1. Conjugation
2. Transduction
3. Transformation (Transforming Principle)

CONJUGATION:
In this process of recombination bacteria attached with each other through pili. Pili of two bacteria after fusion form a tube like structure called conjugation tube (or cytoplasmic bridge) through this tube DNA of one bacteria transfer to another bacteria. This process was carried out experimentally by Laderberg and Tatum in 1946.

TRANSDUCTION:
It is a mode of genetic recombination in which genetic material is transferred from one bacterium to another by a third party which is a bacteriophage. This process was carried out experimentally by Laderberg and Zinder in 1952.

TRANSFORMATION (Transforming Principle):
It is a process of transmitting genetic information from one bacterium to another bacterium through environment causing it to transform (undergo change). This principle was first notified by Fred Griffth in 1928.
(Note: As in question names are asked so do not write description)

(viii) What is the role of potassium in transpiration?
Ans: ROLE OF POTASSIUM IN TRANSPIRATION:
In clay time K⁺ is actively transported by guard cells. Turgor pressure increases because of a negative water potential due to an inflow of potassium ions (K⁺) the cell becomes hypertonic to its environment. Then water comes inside the epidermal cells by osmosis. Reversible uptake of K⁺ ions takes place because of the membrane potential created when H⁺ are actively pumped out of the cell consuming ATP. The cells interior becomes negative compared to the surroundings. Water flows out of guard cells causing them to become flaccid which result the closure of stomata.

OR

(viii) Why do insectivorous plant use insects as food?
Ans: Insectivorous plants are plants which have insects and small birds as their prey. They are found in areas where the soil is poor in nutrients and nitrogen is deficient. They are poor in nitrogen which is very important for the growth of the plants, such as rock outcrops and acidic bogs. They have to depend on insects for their nitrogen and protein requirements. Thus This nitrogen is obtained by digesting the insects.

(ix) Why ATP called as energy currency?
Ans: ATP is known as adenosine triphosphate, and it is a molecule containing carbon, hydrogen, nitrogen, oxygen and phosphorus. ATP is the energy currency of the cell because, it is the most preferred energy molecule in the cell. Its preference is due to the following factors:

1. It donates its phosphoryl groups to release energy.
2. On hydrolysis, it releases a high negative Gibbs free energy which can be drive many important biosynthetic reactions in metabolic pathways.
3. The presence of adenine and ribosyl groups provide additional features for attachment to enzymes so it is able to to regulate enzymatic activities.

Q.3: Attempt any Four part questions. Each question carries two marks. Answer should not be exceed 5 to 6 lines.
(i) Write four important events takes place during light reaction of photosynthesis.
Ans: EVENTS OF LIGHT REACTION:
Following four important event take place during photosynthesis:

1. Photolysis of water.
2. Electron transport chain i.e. PS II and PS I.
3. Reduction of NADP⁺ to NADPH + H⁺
4. Synthesis of ATP by photophosphorylation.

OR

(i) Write note on Diversity among protoctista.
Ans: DIVERSITY AMONG PROTOCTISTA:
The Kingdom Protista consists of eukaryotic protists. Members of this kingdom are very diverse, typically unicellular and less complex in structures and have similarities with other eukaryotes. Due to this diversification, biologists regard protist kingdom as a polyphyletic group of organisms. It means they do not share a single common ancestor.
Here we have divided them into three groups:

1. Plant-like Protoctists-Algae (Chlorella and Ulva)}
2. Fungi-like Protoctists-Primitive fungi (Slime molds and Water molds)
3. Animal-like Protoctists-Protozoa (Trypanosoma, Amoebae, Paramecium)

(ii) Briefly describe the fluid mosaic plasma membrane.
Ans: FLUID MOSAIC MODEL:

• This model was presented by Singer and Nicolson in 1972.
• In the fluid mosaic model, the lipid bilayer is retained as the core of the membrane.
• These lipid molecules are present in a fluid state capable of rotating and moving laterally within the membrane.
• The structure and arrangement of membrane, proteins in the fluid-mosaic model are like icebergs sea.
• Some protein molecules penetrate deeply into and even completely through the lipid sheet.
• The components of plasma membrane are mobile and capable of coming together to engage in various types of transient or semi permanent interaction.
• The protein associated with lipid bilayer can be divided into two groups:
  (i) Integral proteins (intrinsic proteins)
  (ii) Peripheral proteins (extrinsic proteins)

(iii) Describe the concept of species and taxonomic hierarchy of biological classification?
Ans: TAXONOMIC HIERARCHY:
"Taxonomic hierarchy is the process of arranging various organisms into successive levels of the biological classification, either in a decreasing or an increasing order from kingdom to species and vice versa."
UNIT OF BIOLOGICAL CLASSIFICATION:
Following are the units of classification or taxonomic categories:

1. Species:
   The group of living organisms which are not only similar in morphological characteristics but they can also sexually inter breed with each other to give fertile offspring.
2.  Genra: 
   The basic unit of the biological classification is specie. Closely related species are grouped together into Genra.
3. Families:
   Genera are grouped into Families.
4. Order:
   Families are grouped into order.
5. Classes:
   Orders are grouped into classes.
6. Phyla (Division):
   Classes are grouped into phyla (For animals), Division (for plants).
7. Kingdom (Largest unit):
   Phyla or divisions are grouped into kingdoms.

OR

(iii) Point out two problems with having two kingdom system.
Ans: OBJECTIONS OF TWO KINGDOMS SYSTEMS:
There are some problems with two kingdom system of classification which are following:

• First is Euglena which has both animals and plants like characters, have no cell wall like animals and have chlorophyll like plants. They are autotrophic as well as heterotrophic.
• It cannot explain the difference between prokaryotic and eukaryotic.
• Fungi which are totally different from plants also included in kingdom plantae.

(iv) Write postulates of cell theory?
Ans: POSTULATES OF CELL THEORY:
Cell theory is the contribution of Schieiden 1839, Schwann 1839 and Virchow 1855. Cell theory has following points.

1. Cells are the structural and functional unit of living organisms.
2. Cells arise from preexisting cells.
3. Cells contain nucleic acid through which specific characters are passed to the next generation of cells

OR

(iv) Salient features of Cyanobacteria
Ans: FEATURES OF CYANOBACTERIA:

• Blue-Green Algae are a type of photosynthetic bacteria consisting either of single cells or colonies which is also known as the Cyanobacteria. Cyanobacteria contain only one type of chlorophyll, Chlorophyll a, a green pigment in addition , they also contain pigments such as carotenoids, phycobilln.
• These bacteria grow naturally in marine and fresh water systems. They thrive in dams, rivers, reservoir lakes and even in hot springs. These bacteria normally look green and sometimes turns blue when scum are dying. Almost all specie of these bacteria are buoyant and float on the water surface and forms floating mats.
• The accumulation of these algae is termed as blooms. These blooms discolour the water and produce unpleasant taste and odour. They effect the fish population and reduces water quality. The decomposition of these blooms deplete the oxygen and triggers the killing of fish.
• Examples of cyanobacteria: Nostoc, Oscillatoria, Spirulina, Microcystis, Anabaena

v. Write structure and functions of the following: (any one)
Mitochondria
Nucleus
Ans: (I) NUCLEUS:
The nucleus was discovered by a scientist Robert Brown in 1831. It is spherical or oval in shape and is located in the center in a young cell while in a mature cell it comes to lie on one side.
STRUCTURE OF NUCLEUS:
1) NUCLEAR-MEMBRANE:
The nucleus is surrounded by a thin, transparent membrane separates the cytoplasm from the nucleus. The nuclear membrane has numerous large pores which help in direct communication between cytoplasm and the nucleoplasm.
2) NUCLEOPLASM:
In the nucleus there is a dense but clear mass of protoplasm, called nucleoplasm. It contains enzymes and other complex substances which take part in the formation of DNA and RNA.
3) CHROMATIN NETWORK:
In the neoplasm a network of fine loosely connected threads is present called chromatin network. The chromatin is the hereditary material. In division of nucleus the chromatin forms a definite number of thread like structures, called chromosomes, which contain hereditary units on their surface, called genes. Chemically chromatin consists of ribonucleic acid and Deoxyribonucleic acid (DNA).
4) NUCLEOLUS:
In each nucleus one or more globular bodies present, called nucleolus. They consists of proteins and RNA. The nucleolus produce ribosomes, which take part in protein synthesis.

FUNCTION OF NUCLEUS:

• The nucleus controls all the vital activity of a cell, so it is consider the brain of the cell.
• It produces chromosomes during cell division.
• The chromosomes transfer hereditary characters from parent cell to daughter cell.
• It directly takes part in cell division and reproduction.
• It produces DNA and RNA. DNA is a generic material and RNA takes part in protein synthesis.
• In the nucleolus of nucleus ribosomes are produced, which help In protein synthesis.

MITOCHONDRIA OR CHROMOSOMES:
They are small spherical or plate like bodies present in the cytoplasm. Mitochondria are transferred from mother to the new generation. These are present in eggs and not in sperms, so mother transfer them into new generation.
Mitochondria consists of three parts:
1) AN OUTER MEMBRANE:
It is smooth and consists of proteins and lipids.
2) INNER MEMBRANE:
It forms numerous folds, called cristae. On these cristae enzymes and co-enzymes are present which help in oxidation of starch, fatty acids and amino acids. These compounds are converted into CO₂ and water. In this process energy is released in the form of ATP. This energy is stored in the mitochondria.
3) MATRIX:
It is central granular part. It contains many organic compounds.

FUNCTIONS:
Mitochondria are the main centers of the intercellular energy production, they are called power house of the cell. Almost all the respiratory activities take place in mitochondria and they contain a number of enzymes.

(vi) Draw a well labelled diagram of the followings (any one):
♦ Bacteriophage virus
♦ Bacterium
♦ Fern prothallus

BACTERIOPHAGE VIRUS

BACTERIUM

FERN PROTHALLUS

SECTION "C" (DETAILED-ANSWER QUESTIONS)
(Max Marks: 09)

Note: Attempt any two question from this section all question carries equal marks.

Q.4: Explain the life cycle of Moss (No diagram required)
Ans: LIFE CYCLE OF MOSS ( Funaria hygrometrica - Bryophyte):
The life cycle is completed into two stages called alternation of generations.

1. Gametophytic stage
2. Sporophytic stage

It shows heteromorphic alternation of generations.

1. Gametophytic Stage:

• It is the first and dominant phase of life cycle.
• The gametophyte stage is haploid (n), and consisting of rhizoids, pseudo stem and leaves.
• In this phase. the sex organs antheridia (male) and archegania (female) are produced at the tips of stem.
  (i) The Antheridia:
  - The antheridia are club-shaped.
  - Each antheridiurn is surrounded by an outer jacket layer.
  - Inside the anthendium antherozoid mother cells or androcytes are produced.
  - They divide and redivide to form biflagellate male gametes called antherozoids.
  - There is protoandry because antheridia mature earlier and liberate their anthrozoids, which start swimming with the help of their flagella in dew or rainwater.
  
  The Archegonia:
  - Each archigonium is flack-shaped.
  - It consists of three parts stalk, venter and neck .
  - The stalk helps in the attachement of archegonium.
  - Venter is the middle swollen part.
  - It contains a large egg cell (ovum) and a small, venter canal cell.
  - Neck is the upper elongated tube-like part. It contains neck canal cells.

Fertilization:-
The motile anthrozoids move towards the archeeonium in the presence of water. They enter the archegonium through its open mouth and one antherozoid fuses with egg cell (ovum) to form diploid (2n) oospore (zygote). This is retained within archegonium and form an embryo (2n).

2. Sporophytic Stage:

• This embryo undergo repeated mitoticdivisions to form sporogonium (a sporophyte) which is diploid.
• The saprophyte grows upon gametophyte.
• It depends partially or completely for its nourishment upon the tissues of gametophyte.
• The sporophyte consists of three parts, foot seta and capsule.
  (i) Foot:
  Foot helps in the attachment of sporophyte and in the absorption of food from the tissues of gametophyte.
  (ii) Seta:
  The seta is the stalk of capsule.
  (iii) Capsule:
   The capsule produces spore-mother cells. They are diploid (2n).
• They divide by meiosis and form four haploid (n) spores.
• Each spore can germinate into filamentous body called protonema.
• Later on gametophyte (haploid) develops from protonema during favourable conditions to complete life cycle .

(Note : No diagram is required, as mentioned in question.)

OR

(4) Describe adaptive characteristics of Bryophytes to land habitat.
Ans: Adaptive Characteristics Of Bryophytes To Land habitat
The land plants and animals evolved from aquatic living organism. On land, they developed certain characteristics according to the environment.
ln water, the life is easy, because water is essential for all processes of life. The aquatic organisms do nor face dry conditions. The temperature of sea water does not change rapidly in dry land. In this way, the life of aquatic living organism remains continuous in a normal way.
When the plants migrated on land, they faced certain problems. The most important ones are as follows:

• To obtain and conserve water.
• To absorb CO₂ from the atmosphere for photosynthesis.

To solve these problems, the plants changed their body structure according to the environment. First of all, they shifted from aquatic to the amphibians habitat, then they started their life on dry land. Amphibians are the plants which grow on moist places or live body in dry and wet habitat For example. Mosses and Liverworts.
The characteristics cf plants which they adaptive from wet to dry conditions an as follows:

1. Rhizoids for water absorption
2. Conservation of water
3. Absorption of CO₂
4. Heterogamy
5. Protection of reproductive cells
6. Formation of embryos

1. Rhizoid for water absorption:

• These are long, filamentous extensions of the cells of the lower surface of the thallus.
• They greatly increase the surface for absorption of water from the soil.

2. Conservation of water:

• The plant-body called thallus of all bryophytes is multilayered.
• The outer and uppermost layer of cells is covered with cuticle. It is non-cellular layer of wax-like substance called cutin.
• Cuticle is also found in the stem and leaves of highly evolved land plants and is very efficient in reducing the rate of evaporation so water should stay in their body.

3. Absorption of CO₂:

• Land plants need an efficient means for the exchange of gases with the environment in contrast to aquatic plants which exchange gases dissolved in water.
• The upper surface of the thallus is provided with a number of aerating pores, which leads inside into an air-chamber, partially filled with branching filaments of photosynthetic cells.
• These cells absorb CO₂ for photosynthesis i.e manufacture of food.

4. Heterogamy:

• Heterogamy is the most successful kind of reproduction that has evolved in bryophytes.
•  It is defined as production of two different types of gametes, one is male (motile) and the other is female (non-motile) full of stored food.

5. Protection of reproductive cells:

• The land environment requires special protection for the reproductive cells. They are protected by outer covering.
• Moreover, together with these organs, hair like structures called paraphyses are also present which help to prevent drying of the sex organs.

6. Formation of embryos:

• Embryo developed into new amphibious plants is of universal occurrence..
• Egg called oospore (zygote) is formed inside the archegonium.
• An embryo develops from the oospore as it divides, remain inside the protective coverings of the archegonia.
• Thus The coverings formed by the female organ during development, protect the growing embryo from drying out and from mechanical injury.

Q.5: Describe in detail the process of Glycolysis.
Ans: Glycolysis: (Glyco = sugar, Lysis = splitting):
Glycolysis is the initial stage of aerobic respiration. This process starts with glucose. Glucose, a six-carbon molecule is degraded through sequential enzyme dependent reactions into two molecules of pyruvic acid (a three carbon compound).

ATP Provide Energy To The Process

A small amount of energy must be invested by the cell to initiate glycolysis. It is adenosine tri phosphate (ATP) that provides the energy for initiating glycolysis.

Process of glycolysis consists of following steps:
Phosphorylation Reactions:

• The first step in glycolysis is the transfer of phosphate group from ATP to 6-carbon of glucose. Adenosine di phosphate and glucose 6-phosphate are formed.
• After an enzyme catalyses, the conversion of glucose 6-phosphate to its isomer fructose-6-phosphate (F-6-P).
• Another molecule of ATP is invested which transfers its phosphate group this time to 1-carbon of F-6-P forming fructose-1, 6-di phosphate and ADP.
• These reactions are known as phosphorylation reactions because phosphate groups are added to glucose and fructose molecules.

Energy Investment Phase:

• Since two molecules of ATP are used this part of glycolysis is considered as the energy investment phase.
• The next step in glycolysis is enzymatic splitting of fructose 1, 6-di phosphate into two fragments. Each of these two molecules contain three carbon atoms. One is called 3-phosphoglycer aldehyde (PGAL) and other is Dihydroxy acetone phosphate (DHAP).
• These two sugar molecules are isomers to each other and are interconvertible. This is the reaction from which glycolysis derives its name.
• Normally both these molecules are converted into pyruvic acid through subsequent enzyme controlled reactions.

Energy Yielding Phase:

• In the remaining part of glycolysis ATP molecules are synthesized hence it is called energy yielding phase.
• In the following reaction, an enzyme dehydrogenase and a co-enzyme nicotinamide dinucleonde NAD+ work together.
• The enzyme strips off two hydrogen atoms from PGAL. These electrons are captured by NAD+. This is a redox reaction where PGAL is oxidized by removal of electrons and NAD is reduced by the addition of electrons.
• With the loss of two hydrogen atoms PGAL is converted into 1- 3 phosphoglyceric acid (PGA).
• Now PGA picks up phosphate group (Pi) present in cytoplasm and becomes 1-3 di phosphoglyceric acid (DPGA).
• In the very next step DPGA loses its phosphate group to ADP forming ATP and 3-phosphoglycerate. The phosphate group attached with carbon-3 atom of PGA changes its position to carbon-2 atom forming an isomer 2-phosphoglycerate.
• With removal of water molecule 2 PGA is converted into phosphoenol pyruvic acid (PEPA).
• Finally phosphate group is transferred to ADP forming ATP and pyruvic acid.
• Synthesis of ATP during glycolysis is known as substrate level phosphorylation because phosphate group is transferred directly to ADP from another molecule.

OR

Q.5: Light independent reaction (C3 cycle) of photosynthesis.
Ans: Light independent reaction (Dark reaction) or Calvin-Benson Cycle Or (C3 cycle):
Dark reaction:
This is the second phase of photosynthesis, which results in the fixation of atmospheric CO₂ into sugar phosphates. This part of photosynthesis does not require light energy directly, therefore it is generally termed as the 'dark reaction'.
Calvin-Benson Cycle:
This process was explained by Calvin and Benson in the form of a cycle. These reactions require chemical energy in the form of ATP and NADPH2, are collectively known as the Calvin-Benson Cycle (reductive pentose phosphate cycle).
C3 Cycle:
During this cycle CO₂ is reduced to triose-phosphate (phosphoglyceraldehyde and dihydroxyacetone phosphate) and subsequently via other metabolic pathways to carbohydrates. Type of plants in which first stable product is glycerate, 3 phosphate (PGA) contains 3 carbon atom are called C3 plants and the cycle called C3 cycle.

Phases Of Cycle:
This cycle consists of 3 main reactions catalysed by 11 enzymes, and is divide into three distinct phases, which are:

1. Carboxylation or carbon fixation - during which CO₂ is fixed into organic molecules.
2. Reduction of synthesis of phosphoglyceraldehyde (PGAL) by the reduction of organic molecules.
3. Regeneration where the reduced carbon can be utilized either to regenerate the carbon acceptor molecules or for metabolism.

i) Carboxylation:

• This is the first and key reaction of Calvin cycle where ribulose-1, 5-bisphosphate (RuBP) is combined with atmospheric CO₂ to produce a short lived, six carbon (Keto acid) intermediate, which breaks into two molecules of glycerate-3-phosphate (G3P).
• This reaction is catalysed by the enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco).

ii) Reduction:

• This phase of the calvin cycle comprises a series of freely reversible reactions.
• During this phase G3P is reduced to lycerate-1, 3- biphosphate (G1, 3P) and then triose phosphate [ 3 Phosphoglyceraldehyde (GA3P) and Dihydroxyacetonephosphate (DHAP) ] at the cost of ATP and NADPH produced during light reaction.

iii) Regeneration:

• Many carbon rearrangement takes place during this phase.
• Three carbon compounds are rearranged to form 5 carbon units including the primary acceptor molecule, RuBP. This stage involves enzymes 5-11.
• During this cycle 3 molecules of CO₂ fix by 3 molecule of RuBP (3 x C5), which produces 6 molecules of 3-carbon compounds i.e. triose (6 x C3).
• From these 6 molecules five are required to regenerate RuBP:
• (5 x C3 ⟶ 3 x C5).
• Therefore, only one molecule of 3C is produced (generally called triose-phosphate) which can
• (a) re-enter the cycle, or
• (b) be used for starch synthesis within the chloroplast or
• (c) be exported via a phosphate translocator to cytosol for sucrose synthesis.
• For the net synthesis of one G3P molecule, the Calvin cycle consumes a total of nine molecules of ATP and six molecules of NADPH+H+. The G3P spunoff from the Calvin cycle becomes the starting material for metabolic pathways that synthesize other organic compounds, including glucose and other carbohydrates.

Special Thanks To:

By: SIR. DR. M. SAAD BAIG (M. Sc (Microbloiogy), A.D (Counselling Psychology]

GMAIL AND CONTACT: dr.balg267@gmail.com, 0345-2442224-/-0334-2552299-(Whatsapp)

SOURCE: Board Of Intermediate Education Karachi

Biology For Class IX - Chapter No.4 - Cells And Tissues - Continue Questions and Answers - Animals and Plant Tissues

GO TO INDEX

CHAPTER 4
CELLS AND TISSUES

ANIMAL AND PLANTS TISSUES

Q.36: Define tissue? and mention the types of tissue?
Ans: TISSUES:
A group of cells which are similar in shape and functions is called tissue.

OR

A group of similar cells that work together to perform a common function is known as a tissue.
For example: The cells in the small intestine that absorb nutrients look very different from the muscle cells needed for body movement.

Q.37: Name the types of animal tissues?
Ans: ANIMAL TISSUES:
Humans and other large multicellular animals are made up of four basic types tissues:

1. Epithelial tissue
2. Connective tissue
3. Muscular tissue and
4. Nervous tissue

Q.38: Define epithelial tissues? Describe types of epithelial tissues in detail with diagrams (where necessary)?
Ans: EPITHELIAL TISSUES:

• Epithelial tissue covers the surface of the body, lines the spaces inside the body (i.e organs and cavities) and forms glands.
• For instance, the outer layer of our skin is an epithelial tissue and the lining of small intestine are made up of epithelial tissues.
• Epithelial cells are polarized, means that they have a top and a bottom side.

Types Of Epithelial Tissues

There are different types of epithelial tissue depending on their function in a particular location. The simplest classification of these tissues is based on the number of cell layers.

1. Simple Epithelial Tissue
2. Stratified Epithelial Tissue

1. Simple epithelial tissue:
   When the epithelium is composed of a single layer of cells, it is called simple epithelial tissue.
   
   
Types Of Simple Epithelial Tissue:
On the basis of function, these tissues are classified as:

1. Simple squamous epithelium:
   Location: are found in the alveoli of lungs.
   Function: its structure is important for the exchange of gases between the blood and lungs.
   
   
2. Simple Cuboidal Epithelia:
   Location: line the lumen of collecting ducts in the kidney and are present in the thyroid gland around the follicles.
   Function: secrete thyroid hormones.
   
   
3. Simple Columnar Epithelia:
   Location: are found in the female reproductive system and in the digestive tract.
   Function: secretion.


2. Stratified epithelial tissues:
   When the epithelium is containing two or more layers of cells are called stratified epithelial tissues.
   
   Types Of Stratified Epithelial Tissues:
Stratified epithelia consist of more than one layer of cells and only one layer is in direct contact with the basement membrane.


1. Stratified Squamous Epithelia:
   Location: are found in skin, with many dead, keratinized cells.
   Function: provide protection against water and nutrient loss.
   
   
2. Stratified Cuboidal Epithelia:
   Location: are found surrounding the ducts of many glands, including mammary glands in the breast and salivary glands in the mouth.
   Function: helps in secretion and protection.
   
   
3. Stratified Columnar Epithelia:
   Location: are rare, found predominantly in some organs of the reproductive system.
   Function: protection.
   
   
4. Transitional epithelia:
   Location: They are a special subset of stratified epithelia. They are exclusively found in the excretory system.
   Function: Protection and transit shape of cells.

Q.39: Define the connective tissues and its type?
Ans: CONNECTIVE TISSUES:
Those tissue which connects or bind the different types of cells called connective tissues. They also bind other tissues of the body with each other. Connective tissue holds structures in the body together, such as tendons.

Types Of Connective Tissues:
There are two type of connective tissues:

1. Supporting connective tissues
2. Fluid connective tissue

a) Supporting Connective Tissues:
There are three types of supporting connective tissues.

• Cartilage:
  * It is a type of supporting connective tissue.
  * It is a dense connective tissue.
  * Cartilage has limited ground substance and can range from semisolid to a flexible matrix.
  * e.g: Cartilage present in pina of ear
  
  
• Bone:
  * It is another type of supporting connective tissue.
  * Bone can either be compact (dense) or spongy (cancellous), and contains the osteoblasts or osteocytes cells.
  
  
• Adipose:
  * It is another type of supporting connective tissue that provides cushions and stores excess energy and fat.

b) Fluid Connective Tissue:

• Blood:
  Blood referred to as fluid connective tissue. It transports materials in the body.

Q.40: What do you know about muscles tissues and its types?
Ans: MUSCLES TISSUES:

• Muscle tissue are most abundant tissues in animal.
• They contain bundles of long cells.
• Function: contains the cells that are responsible for the contraction and relaxation of muscles.

Types Of Muscle tissues:
There are three types of muscular tissues i.e.

1. Skeletal
2. Cardiac
3. Smooth

Skeletal Muscle:

• Skeletal muscle, which is also called striated (striped) muscle, is what we refer to as muscle in everyday life.
• Skeletal muscle is attached to bones by tendons.
• For instance, the muscles in our legs and our arms are skeletal muscle.
• Function: responsible for the movement of bones.

Cardiac Muscle:

• Cardiac muscle is found only in the walls of the heart.
• Like skeletal muscle, cardiac muscle is striated, or striped. But it's not under voluntary control.
• Function: responsible to produce heart beat involuntary. It means we don't need to think about making our heart beat.

Smooth Muscle:

• Smooth muscle is found in the walls of blood vessels, as well as in the walls of the digestive tract, the uterus, the urinary bladder, and various other internal structures.
• Smooth muscle is un-striped, (unstriated), it is involuntary, not under conscious control.
• Function: responsible to produce movement of food through our digestive tract and we don't need to think about it (involuntary).

Q.41: Write a short note on nervous tissue? Draw a labelled diagram of neurons?
Ans: NERVOUS TISSUES:

• It is composed of neurons.
• It is found in the brain, spinal cord, and nerves.

Function Or Role Of Nervous Tissues In Body:

• Neurons transmit information to other cells.
• It is responsible for coordinating and controlling many body activities.
• It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning.
• To do all these things, cells in nervous tissue need to be able to communicate with each other by way of electrical nerve impulses.

Q.42: What are plant tissue? Describe its type?
Ans: PLANT TISSUES:
As same in animals, plant cells are grouped into tissues with characteristic functions such as photosynthesis, transport etc.

Major Types Of Plant Tissues:
There are two major categories of tissues in plants i.e.

1. Meristematic tissues and
2. Permanent tissues

1. MERISTEMATIC TISSUES:

• These tissues are composed of cells, which have the ability to divide.
• The cells are thin walled, have large nucleus and number of small vacuoles.
• Usually they do not have inter-cellular spaces, so the cells are arranged compactly.

Types Of Meristematic Tissues:
Two main types of meristematic tissues recognized in plants are:

• Apical meristems
• Lateral meristems

(A) Apical meristems:

• Thy are present at the apex of roots and stems.
• According to their position they are Apical meristems.
• Function: Stem and root increase in length by the division of cells of these tissues. This type of growth is called primary growth.

(B) Lateral meristems:

• They are located on the lateral sides of roots and shoot.
• Function: When they divide, they are responsible for increase in growth of plant parts. This growth is called secondary growth.

2. PERMANENT TISSUES:

• Permanent tissues originate from meristematic tissue.
• The cells of these tissues do not have the ability to divide and may have intercellular spaces in between cells.

Types Of Permanent Tissues:
Permanent tissues are further classified into following two types either on the basis of position or composition:

• Simple permanent tissue
• Compound or complex tissue

(A) Simple Permanent Tissue:
Simple permanent tissues are made up of only one type of cell. They are further divide as:

• Epidermal Tissues
• Ground Tissues
• Supporting Tissues

(i) Epidermal Tissues:

• They are composed of a single layer of cells and they cover plant body.
• Function:
  i) They act as a barrier between environment and internal plant tissues.
  ii) In roots, they are also responsible for the absorption of water and minerals.
  iii) On stem and leaves they secrete cutin (the coating of cutin is called cuticle) which prevents evaporation.
  iv) They also have some specialized structure that perform specific functions.
  For example root hairs and stomata.

(ii) Ground tissues:

• They are simple tissues made up of parenchyma cells.
• Parenchyma cells are the most abundant cells in plants.
• Overall they are spherical but flat at point of contact.
• They have thin primary cell walls and have large vacuoles for storage of food.
• Function:
  i) In leaves, they are called mesophyll and are the sites of photosynthesis.
  ii) In other parts, they are the sites of respiration and protein synthesis.
  iii) They also store food in their vacuole.
  iv) Most parenchyma cells can develop the ability to divide and differentiate into other types of cells and they do so during the process of repairing an injury.

(iii) Supporting Tissues:

• These tissues provide strength and flexibility to plants.
• They are further of two types.
  a) Collenchyma Tissues
  b) Sclerenchyma Tissues
  
  
• a) Collenchyma Tissues: 
  i) They are found in cortex (beneath epidermis) of young stems and in the midribs of leaves and in petals of flowers.
  ii) They are made of elongated cells with unevenly thickened primary cell walls.
  Function:
  iii) They are flexible and function to support the organs in which they are found.
  
  
• b) Sclerenchyma Tissues:
  i) They are composed of cells with rigid secondary cell walls.
  ii) Their cell walls are hardened with lignin, which is the main chemical component of wood.
  iii) Mature sclerenchyma cells cannot elongate and most of them are dead.

(B) Compound (Complex) Tissues:

• A plant tissue composed of more than one type of cell is called a compound or complex tissue.
• They are found only in vascular plants.
• Examples of compound tissues are:
  Xylem tissues and
  Phloem tissues

(i) Xylem Tissue:
Xylem tissue consists of dead cells.
Due to the presence of lignin, the secondary walls of its cells are thick and rigid.

Types of cells Found in Xylem:
Two main types of cell are found in xylem tissue i.e:

1. Vessel: Vessels have thick secondary cell walls. Their cells lack end walls and join together to form long tubes.
2. Tracheids: Tracheids are made up of slender cells with overlapping ends.

Function:

• Xylem tissue is responsible for the transport of water and dissolved substances from roots to the aerial parts.
• Xylem tissue also provides support to plant body, due to presence of lignin

(ii) Phloem Tissue:
Phloem tissue consists of living cells and mainly contains:

• Sieve tube cells and
• Companion cells

1. Sieve tube:
   Sieve tube cells are long and their end walls have small pores.
   Many sieve tube cells join to form long sieve tubes.
   
   
2. Companion cells:
   Companion cells are parenchymatous, narrow, elongated cells, and are closely associated with the sieve tube.

Function:

• Phloem tissue is responsible for the conduction of dissolved organic matter (food) between different parts of plant body.
• Conduction with the sieve tube is done through the pores present on the walls of these cells.
• They help the sieve tubes in conduction of food materials and make proteins for sieve tube cells.

Q.43: Draw the outline or the chart of the plant tissues?

OR

Q.44: Differentiate between xylem and phloem?
Ans: Difference Between Xylem and Phloem:

S.NO.	Xylem	Phloem
1.	Xylem tissue is responsible for the transport of water and dissolved substances from roots to the aerial parts.	Phloem tissue is responsible for the conduction of dissolved organic matter (food) between different parts of plant body.
2.	Xylem tissue consists of dead cells.	Phloem tissue consists of living cells.
3.	Transport is unidirectional i.e. from roots to apical parts of the plants.	Transport is bidirectional i.e. from leaves and storage organs to different parts of plants.
4.	Xylem tissues consists of vessels and tracheids	Phloem tissues consists of Sieve tube cells and Companion cells
5.	Xylem cells are star shaped.	Phloem cells are not star shaped.

Q.45: Comparison between parenrenchyma, Sclerenchyma and Collenchyma.
Ans: Between Parenrenchyma, Sclerenchyma and Collenchyma

S.NO.	Parenchyma	Collenchyma	Sclerenchyma
1.	They are simple, living storage tissues.	They are simple, living mechanical tissues.	They are simple, dead mechanical tissues.
2.	They formed ground tissues and epidermis and are the most abundant cells in plants.	They formed supporting tissues and are found in cortex (beneath epidermis) of young stems and in the midribs of leaves and in petals of flowers. Absent in roots.	They formed supporting tissues and are found in all the region of plant body, particullarly in the fruit wall and seed coat.
3.	They are spherical or oval in shape but flat at point of contact.	They are flexible and made of elongated cells or irregular in shape.	They are also enlongate or iregular in shape. But mature sclerenchyma cells cannot elongate
4.	They have thin primary cell walls.	They have unevenly thickened primary cell walls.	They are composed of cells with rigid secondary cell walls. Their cell walls are hardened with lignin, which is the main chemical component of wood.
5.	They have large vacuoles for storage of food.	They have small or no vacuoles.	Vacuoles are absent
6.	They are loosely arranged with intercellular spaces.	They are compactly arranged with few, small or no intercellular spaces.	They are very compactly arranged with no intercellular spaces.
7.	they are the sites of respiration and protein synthesis.	They give flexible support to the organs in which they are found.	They provide rigidity support and protection to the plants.

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