IndraprasthaWORLD SCHOOL
Paschim Vihar, New Delhi-110063.
SESSION 2017-18
Half Yearly Examination
BIOLOGY (044)
(SET-B)
Class: XIMaximum Marks: 70
Date:19.9.2017Time Allowed: 3 Hours
MODEL ANSWERS AND THE MARKING SCHEME
SECTION-A1. / Carolus Linnaeus / 1
2. / Growth in Plants / Growth in Animals
-Growth occurs in certain regions, called meristems.
-Growth occurs throughout their life. / -Growth occurs all over the body.
-Growth stops after a certain period.
/ ½+½
3. / It is a fungus living on the dung of animals. / 1
4. / Fruit formed without fertilization of ovary, it is called parthenocarpic fruit. / 1
5. / A. Alternate phyllotaxy
B. Opposite phyllotaxy / 1
SECTION-B
6. / - Bulliform Cells are certain adaxial epidermal cells along the veins, which have become large and colourless.
- When bulliform cells are turgid, the leaf surface is exposed; when they are flaccid the leaves curl inwards and the surface is not exposed. / 1+1
7. / - Porins are the proteins that form huge pores in the membranes to allow molecules to pass through.
-They allow movement of substances across the outer membrane of plastids, mitochondria, etc. / 1+1
8. / - It is a method of naming the organisms, in which every organism is given a scientific name, which has two parts (words); the first is the name of the genus (generic name) and the second part is the name of the species (specific epithet). e.g., mangifera indica. / 1+1
9. / Photosynthetic refers to the algal partner in lichens Mycobiont refers to the fungal partner in lichens. / 1+1
10. / Parapodia are the lateral triangular appendages that help in swimming; it is found in Nereis. (any other example can be considered.)
Or
In Urochordata, the notochord is restricted to the tail region, only in the larval stage. In Cephalochordata, it extends from head to tail and persists throughout life. / 2
1+1
SECTION-C
11. / Gametophyte / Sporophyte
-It is the haploid phase in the life cycle.
-It reproduces sexually by the formation of gametes.
-It gives rise to the sporophyte. / -It is the diploid phase in the life cycle.
-It reproduces asexually by the formation of spores.
- It gives rise to the gametophyte.
/ 1+1+1
12. / a. An embryo sac has three antipodal cells, a female gamete, two synergids and a central cell with secondary nucleus.
b.
Synagamy / Triple fusion
-It is the process of fusion of a male gamete with the female gamete.
-It results in a diploid zygote. / -It is the process of fusion of two polar nuclei (into a secondary nucleus) and a male gamete in the embryo sac.
-It result in a triploid primary endosperm nucleus (PEN).
/ 2+1
13. / a. - In gymnosperms, the ovules are naked, i.e., they are not enclose in an ovary; so the seeds are also exposed as fruit is not formed.
- In angiosperms, the ovules are present within the ovary; the ovary develops into a fruit, with the ovules developing into seeds inside.
-So the gymnosperms and angiosperms are classified differently.
b. These plants can live on land, but depend on water for sexual reproduction;
hence, are called amphibians of plant kingdom. / 2+1
14. / a. Parasitic Platyhelminthes have a thick cuticle. They lack alimentary canal and absorb the nutrients directly through their body surface. Some parasites are provided with hooks and suckers.
b. When the coelom is completely lined by mesoderm, it is a true coelom.
c. Metagenesis is the phenomenon, i.e., polyps produce medusa asexually and medusa produce polyps sexually. / 1+1+1
15. / Regions of the root are as follow.
i. A thimble-like structure called root cap is present.Meristematic region lies just above the root cap extending upto a few millimeters.
ii. The region of elongation lies proximal to the meristematic region.
iii. The region of maturation lies just above the region of elongation.A cluster of root hair arises from the epidermal cells of the region of maturation.
/ 3
16. / a. Apical Meristems
- Those meristems, which occur at the apices/tips of roots and shoots, are called apical meristems.Apical meristems form the primary tissues of the plant and help in growth in length, i.e., they help in primary growth of the plant.
-During the formation of leaves and elongation of stem, certain cells of the shoot apical meristem are left behind and they constitute the axillary buds, which are present in the axils of leaves.
b. Intercalary Meristems
- The meristems which occur in between mature tissue, are known as intercalary meristems.They are present at the bases of internodes and leaf sheaths of grasses and other monocots.
-In grasses, they help to regenerate the parts removed by the grazing herbivores; they also help in primary growth of plants.
c.Lateral Meristems
- Those meristems which are found parallel to the outer surface of the mature part
of plant, are called lateral meristems.
- They help in growth in thickness of the plant.
- They form secondary tissues. / 1+1+1
17. / - Epidermis of leaves is interrupted by small pores, called stomata.
- Each stoma is surrounded by two guard cells; the guard cells are bean-shaped in dicot plants and dumb-bell shaped in monocots.
-The epidermal cell in the vicinity of guard cells become specialized in their size and shape and such cell, are called subsidiary cells.
/ 3
18. / a. The mouth parts include the following structures
i.Labrum is also called upper lip that helps in holding food particles during feeding.
ii.Mandibles lie on the sides of the mouth just behind the labrum. The two mandibles work against each other in a horizontal plane to crush and cut the food into pieces.
iii. Fist maxillae are a pair of maxillae that lie beneath the mandibles, one on either side of the head.
iv. Second maxillae or labium is also called lower lip.
b. Differentiate between bones and cartilage-
Bone / Cartilage
-It is a solid, rigid and strong connective tissue
-Osteocytes occur singly in a lacuna.
-Matrix is deposited with salt of calcium and phosphorus.
-Haversian systems are present.
-Matrix is in the form of concentric lamellae. / -It is a solid, semirigid and flexible connective tissue.
-Chondrocytes occur in clusters of 2 or 3 in each lacuna.
-No calcium and phosphorus salts are present in the matrix.
-Haversian system are absent.
-Matrix does not show any concentric lamellae.
(any two)
/ 2
1
19. / a. i. Axile placentation e.g., China rose, lemon. (any one example)
ii. parietal placentation e.g., cucumber, watermelon. (any one example)
b. Differentiate between racemose and cymose inflorescence.
Racemose Inflorescence / Cymose Inflorescence
-The terminal bud of the inflorescence axis continues to grow, i.e., the main axis has unlimited growth.
-Flowers are arranged in an acropetal order, i.e., older flowers are towards the base while the younger flowers are towards the apex. / -The terminal bud of the inflorescence axis forms a flower, i.e. the main axis has limited growth.
-Flowers are arranged in a basipetal succession, i.e., older flowers is towards the apex and younger flowers are towards the base.
c. When the petals of a flower are free from one another, it is called polypetalous. / ½+½
1
1
20. / a. i. Tip of nose ii. Pinna of ear
iii. Between adjacent vertebrae in the vertebral column. iv. Joints in the limbs.
(any two)
b. Osteocytes
c. Differentiate between striated and smooth muscles.
Striated Muscles / Smooth Muscles
- Cell are cylindrical and unbranched.
- Striations are prominent.
- They are voluntary in function.
- The cells are multinucleate.
- They are attached to the skeletal system. / - Cell are spindle shaped with a broad centre.
- Striations are absent.
- They are involuntary in function.
- The cell are uninucleate.
- They are found in the walls of visceral organs.
(any two) / 1
1
1
21. / The interphase, though called the resting phase, is the time during which the cell is preparing for division by undergoing cell growth and DNA replication,
The interphase is divided into three further phases
- G1-phase (Gap-1) b. S-phase (synthesis) c. G2-phase (Gap-2)
During the G2-phase, proteins are synthesized in preparation for mitosis, while cell growth continues. Cell in this stage remain metabolically active, but no longer proliferate unless called on to do so depending on the requirement of the organism. / 3
22. / -Each chloroplast is double-membrane bound, where the inner membrane is relatively less permeable.
- The interior is filled with a matrix, called stroma.
- A number of organized, flat membranous sacs, called thylakoids are present in the stroma.
- Thylakoids may be arranged as stack/piles of coins called grana or as intergranal thylakoids; the membranes of thylakoids enclose a space, called lumen.
-The stroma of the chloroplast contains enzymes for photosynthesis, a small circular DNA molecules, RNA moleucles and 70 S ribosomes; they are semiautonomous organelles.
(along with diagram)
OR
(any six correct labellings) / 3
3
SECTION-D
23. / a. Mass flow
b. - Source is that part of the plant which synthesizes the organic food, i.e., the
leaves or it is the part of the plant where organic substances are loaded into the
phloem.
- Sink is that part of the plant, to where organic substances have to be transported for use.
c. At the source, when sugar enters the phloem, a hypertonic condition is created; water enters the phloem by osmosis and a higher osmotic pressure is developed.
- So, the sap moves towards regions of lower osmotic pressure.
d. Going with team should be your spirit. / 4
SECTION-E
24. / a. Birds are warm blooded or homeothermal animals as they are able to maintain
constant body temperature. This help them to maintain high metabolic rate for
quick energy supply for flight.
b. Features of cartilaginous fishes
i. Cartilageinous endoskeleton is present.
ii. These are mostly marine, poikilothermic animals.
iii. Notochord is persistent throughout life.
iv. Placoid scales are present.
v. Heart is two chambered with one auricle and one ventricle.
vi. Tail fin is always heterocercal.
OR
a.Differentiate between polyp and medusa.
Polyp / Medusa
It is a fixed zooid. / It is free swimming.
It is asexual. / It is sexual.
It is cylindrical in outline. / Medusa is umbrella-shaped
Tentacles found at upper end of manubrium / Tentacles occur along the margin of umbrella.
Mouth is circular and terminal over upright manubrium. / Mouth is four sided, lies at the lower end of hanging manubrium.
Velum and sense organs are absent. / Medusa have a circular velum and eight sense organs or statocyts.
(any two)
- The criteria used for classifying animal kingdom are:
- Patterns of arrangement of cells.
- Body symmetry
- Nature of coelom
- Presence or absence of notochord
- Diploblastic and triploblastic conditions
- Segmentation of the body.
2+3
25. / a. Since the number of chromosomes in the parent cell and the daughter cells is the same, mitosis is called equational division
b. Chiasmata are the X-shaped structures found at the point of crossing over. They represent the sites of cross over and hence exchange of genetic material or recombination occurs.
c. Mitosis occurs in the somatic (body) cells of plants and animals, where growth is involved.
i. Growth in multicellular organisms is by mitotic divisions.
ii. Repair of injured tissues and replacement of worn out cells is by mitosis.
OR
- G0 (quiescent phase) represents an inactive stage in the cell cycle, where cells are metabolically active but do not undergo division, unless it becomes necessary to replace any worn out or injured cell.
-Two daughter cells are formed.
-For every duplication of DNA, there is one division of nucleus and cytoplasm.
-The daughter cells receive the same number of chromosomes as the parent cell.
-The daughter cells are identical to the parent cell and between cell and between themselves.
-It occurs in all cells
-haploid, diploid, etc.
-Prophase is not as long as prophase I.
-Synapsis and crossing over do not occur.
-The chromosomes are arranged in a single row along the centre of the spindle, with the formation of a metaphasic plate in metaphase.
-Centromere of every chromosome divides and one half of the entromere along with one chromatid (now it is a daughter chromosome) moves towards the pole.
/ -Four daughter cells are formed.
-For every duplication of DNA, there are two nuclear and cytoplasmic divisions.
-The daughter cells receive half the number of chromosomes as the parent cell.
-The daughter cells are different among themselves and do not resemble the parent cell.
-It occurs in diploid cells or cells with even number of sets of chromosomes.
-Prophase I is typically a longer phase.
-Synapsis and crossing over are characteristic of prophase I.
-The chromosomes are arranged in two rows near the centre of the spindle in metaphase; there is no formation of a metaphasic plate.
-One whole chromosome from every homologus pair of chromosome moves towards one pole, while the other whole chromosome of the pair moves towards the opposite pole during Anaphase I.
(any six) / 1
2
2
2
3
26. / Centromere is the non-stained region that holds the chromatids together in a chromosome.
Depending on the position of centromere, the chromosomes are of the following types:
i. Telocentric – the centromere is terminal and so the chromosome has only one arm.
ii. Acrocentric – the centromere is situated closer to one end, making one arm extremely short and the other arm very long.
iii. Submetacentric – the centromere is little away from the centre and so one arm is slightly longer than the other.
iv. Metacentric – the centromere is right in the middle and the two arms of the chromosome are equal in length.
OR
a.
(any correct six labellings)
- –Plasmodesmata are the cytoplasmic bridges, that traverse the primary cell wall
and middle lamella and connect the adjacent cells.
3
1+1
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