Oswal 61 Sample Question Papers ICSE Class 10 Biology Solutions
Section-A
Answer 1.
(i) (c) Urochrome
When urobilinogen gets exposed to air, it is oxidised to urochrome which gives urine its yellow colour.
(ii) (c) Iris
The iris is the colored part of the eye that surrounds the pupil, which is the black opening in the center of the iris. The iris contains pigmented cells that give it its unique color, such as blue, green, brown, or hazel. It controls the size of the pupil, which regulates the amount of light entering the eye. The muscles within the iris contract or relax to adjust the size of the pupil in response to varying light conditions. This helps to protect the sensitive structures within the eye and optimize visual clarity.
(iii) (a) Heterotrophs do not synthesize their own food.
Heterotrophs belong to the trophic level of consumers and consume food made by the autotrophs. They do not contain chlorophyll to make their own food.
(iv) (d) Axonal end of one neuron to the dendritic end of another neuron.
Synapse is defined as the close contact made by the presynaptic terminal (axonal end) and the post synaptic terminal (dendritic end).
(v) (c) TtWW
If all the plants have violet flowers, it indicates that the parent with violet flowers is homozygous for the violet allele. On the other hand, if half of the plants were short, it suggests that the parent tall plant was heterozygous for the tall allele.
(vi) (a) Gamete, zygote, embryo, seedling
The male and female reproductive systems produce gametes, which fuse to form a zygote. This zygote then develops into an embryo, eventually giving rise to a seedling.
(vii) (a) Both A and R are True.
Meiosis is a crucial process in sexual reproduction, and the assertion states that it is necessary for sexual reproduction in organisms. This assertion is correct because meiosis is responsible for the formation of gametes, which are the reproductive cells involved in sexual reproduction. The reason provided is that meiosis ensures the halving of the chromosome number in gametes, which is necessary to maintain the correct chromosome number during fertilization. This reason correctly explains the assertion because, during meiosis, the parent cell undergoes two successive divisions, resulting in the production of four
haploid daughter cells. These haploid cells have half the number of chromosomes compared to the parent cell, ensuring that when two gametes fuse during fertilization, the resulting zygote has the correct chromosome number for the species. Therefore, Both A and R are True.
(viii) (a) DNA undergoes specific changes in germ cell.
The formation of a new species typically involves genetic changes that result in distinct characteristics and reproductive isolation. Significant changes in DNA, particularly in the germ cells (sperm or egg cells), can lead to the emergence of new traits and genetic variations. These genetic changes can accumulate, causing populations to diverge and eventually become reproductively isolated.
This reproductive isolation prevents gene flow between the populations, allowing them to evolve independently and potentially giving rise to new species.
(ix) (d) Mouth → Oesophagus → Stomach → Small intestine → Large intestine
We ingest food through the mouth, which is connected to a tube called the oesophagus which leads the food and other secretions from mouth to the stomach which is further connected to the small intestine and finally transfers the food to the large intestine before eliminating the waste of the body.
(x) (b) Grass, wood, and plastic
All these three compounds can be decomposed by bacteria and hence, are biodegradable items.
(xi) (c) Wind, wood, and Sun
All three of these items occur naturally in the environment and have no negative impact on the environment when used.
(xii) (b) Grass, goat, and human
The grass is an autotroph, it can produce its own food through photosynthesis. Goats, in turn, consume grass as part of their diet. Subsequently, other animals may consume goats as a source of nutrition.
(xiii) (b) Telophase
When the chromosomes reach the poles in anaphase, spindle fibres disappear and the chromosomes start to uncoil at the poles, it indicates the phase called telophase.
(xiv) (c) Hearing loss
Noise pollution is excessive or disturbing noise that can harm human health and the environment. One of the harmful effects of noise pollution is hearing loss. Prolonged exposure to loud noises can damage the delicate structures of the inner ear, leading to permanent hearing impairment. This is particularly true when individuals are exposed to loud noises for extended periods, such as in noisy workplaces or environments with constant high-intensity noise. Hearing loss can significantly impact an individual’s quality of life, communication abilities, and overall well-being. It is important to mitigate and reduce noise pollution to prevent such adverse health effects.
(xv) (b) Controlling plant growth and development
Phytohormones, or plant hormones, are chemical substances produced naturally within plants that regulate various physiological processes. One of the primary functions of phytohormones is to control plant growth and development. These hormones are crucial in coordinating cell division, elongation, and differentiation, influencing seed germination, root and shoot growth, flowering, and fruit ripening.
They regulate plant responses to environmental stimuli, such as light, gravity, and temperature, enabling plants to adapt and optimize their growth and development in changing conditions.
Answer 2.
(i) (a) Metacentric
(b) Hepatic portal vein
(c) Renal medulla
(d) Thoracic cavity
(e) Antidiuretic hormone (ADH)
(ii) (a) Apical Meristem, shoot, soil, Root
(b) Cerebrum, Corpus callosum, thalamus, medulla oblongata
(c) Left atrium, left ventricle, right atrium, right ventricle
(d) Buccal cavity, oesophagus, stomach, duodenum
(e) Prophase, metaphase, anaphase, telophase
(iii) (a) Sutton
(b) Boveri
(c) William Bateson
(d) Gene
(e) heterozygous
(iv) (a) Odd: Ovule; Category: Term related to heredity
(b) Odd: ATP; Category: Blood cells
(c) Odd: Potassium nitrate; Category: Bacteria
(d) Odd: Progestin; Category: Contraceptive method
(e) Odd: Scrotal sacs; Category: Part of female reproductive system
(v)
| Column I | Column II |
| (a) Metaphase | (3) Chromosome become arranged in a horizontal plane at the equator. |
| (b) Heart attack | (5) Blocking of coronary artery. |
| (c) Renal artery | (4) That brings waste filled–blood from the aorta to the kidney. |
| (d) Cranial nerves | (2) Twelve pairs of nerves. |
| (e) Diffusion | (1) The process by which the molecules of perfume spread in the room when the bottle is open. |
Section-B
Answer 3.
(i) Leptotene: It is the first substage of prophase-I in meiosis in which the chromosomes become visible as single threads.
(ii) No, because the mother has only one type of sex chromosome i.e., X chromosomes but a father has two types of chromosomes X and Y-chromosomes. So, all children will inherit the X-chromosome from the mother and whether X or Y-bearing sperm from the father fertilizes the egg will determine the sex of the new born.
(iii) The evaporation of water from the leaves of a plant is called transpiration.
Functions of transpiration:
- It helps in the upward movement of water and minerals from the root to the leaves through the stem.
- Helps in cooling the plant surface.
(iv) Plant hormones or phytohormones are the chemical substances present in plants which coordinate and control various activities of plants like growth, development, response to stimuli etc. There are different types of hormones like auxins, gibberellins, cytokinins, abscisic acid, ethylene etc.
(v) (a) Red blood cells
(b) RBCs side view
(c) Basophil
Answer 4.
(i) ATP – Adenosine triphosphate
(ii) Nitrogenous bases: Adenine and Guanine (others: Cytosine, Thymine, Uracil)
(iii) (a) Pea: Pisum sativum
(b) The two genetic disorders are: Sickle cell anaemia and Down syndrome (Trisomy 21)
(iv) (a) Ovulation
(b) Menarche
(v) (a) The light factor is being studied in this experiment.
(b) The plant was kept in a dark room before conducting the experiment to ensure that no
photosynthesis occurred and that the starch stored in the plant’s leaves was used up. This allows for a clear observation of the effects of light on photosynthesis.
(c) At the end of the starch test, we will observe that the leaf exposed to light (covered by black paper) will turn blue-black when treated with an iodine solution. This indicates the presence of starch, which is produced during photosynthesis in the presence of light. The leaf not exposed to light (covered by the black paper clip) will not show the blue-black color, indicating the absence of starch due to the lack of photosynthesis in the absence of light.
Answer 5.
(i) Phosphorylation is the process of adding a phosphate group to a molecule. It often occurs in biological systems, where enzymes called kinases transfer phosphate groups from ATP (adenosine triphosphate) to target molecules, such as proteins, nucleotides, or sugars. Phosphorylation plays a critical role in cell signaling, metabolism, and regulation of protein activity.
(ii)
| (a) Leaf | Liver |
| Glucose is stored in the form of starch. | Glucose is stored in the form of glycogen. |
| (b) Hypotonic solution | Hypertonic solution |
| A hypotonic solution has a lower solute concentration compared to the cytoplasm of the plant cell. When a plant cell is placed in a hypotonic solution, water will enter the cell by osmosis, causing the cell to swell and become turgid. | A hypertonic solution has a higher solute concentration compared to the cytoplasm of the plant cell. When a plant cell is placed in a hypertonic solution, water will leave the cell by osmosis, causing the cell to shrink and become plasmolyzed. |
(iii) (a) Karyotype
(b) Diapedesis
(iv) (a) Amniotic fluid
(b) Biodegradable waste
(v) (a) Flaccidity
(b) Hypertonic solution
(c) 1. Nucleus, 2. Plastids, 3. Small vacuole, 4. Hypertonic solution.
Answer 6.
(i) Natality refers to the birth rate or the number of individuals born in a population over a specific period of time. It is a measure of population growth and is usually expressed as the number of births per thousand individuals in a population.
(ii)
| Binary fission | Multiple fission |
| 1. A single-parent cell divides into two daughter cells. | It results in the production of many daughter cells. |
| 2. The nucleus divides once, and then each nucleus gets surrounded by cytoplasm to form two individuals. | Nucleus divides repeatedly to form many nuclei and each gets surrounded by cytoplasm to form many daughter cells. |
(iii)
| (a) Corpus callosum | Corpus luteum |
| It transfers information from one cerebral hemisphere to the other. | It secrets progesterone and oestrogen. |
| (b) Sensory neuron | Motor neuron |
| It carries impulses from the receptors to the nervous system. | It carries impulses from the central nervous system, to the effector organ / muscle. |
(iii) (a) Karyotype
(b) Diapedesis
(iv) (a) Amniotic fluid
(b) Biodegradable waste
(v) (a) Flaccidity
(b) Hypertonic solution
(c) 1. Nucleus, 2. Plastids, 3. Small vacuole, 4. Hypertonic solution.
Answer 6.
(i) Natality refers to the birth rate or the number of individuals born in a population over a specific period of time. It is a measure of population growth and is usually expressed as the number of births per thousand individuals in a population.
(ii)
| Binary fission | Multiple fission |
| 1. A single-parent cell divides into two daughter cells. | It results in the production of many daughter cells. |
| 2. The nucleus divides once, and then each nucleus gets surrounded by cytoplasm to form two individuals. | Nucleus divides repeatedly to form many nuclei and each gets surrounded by cytoplasm to form many daughter cells. |
(iii)
| (a) Corpus callosum | Corpus luteum |
| It transfers information from one cerebral hemisphere to the other. | It secrets progesterone and oestrogen. |
| (b) Sensory neuron | Motor neuron |
| It carries impulses from the receptors to the nervous system. | It carries impulses from the central nervous system, to the effector organ / muscle. |
(iv) (a) Root pressure: The pressure developed in the cortical cells of the root, which pushes the water into the xylem vessels of the stem are called root pressure.
(b) Turgidity creates root pressure which helps in the ascent of sap.
(v) Self-pollination among F1
TtRr × TtRr
In F2 generation:
| TR | Tr | tR | tr | |
| TR | TTRR | TTRr | TtRR | TtRr |
| Tr | TTRr | TTrr | TtRr | Ttrr |
| tR | TtRR | TtRr | ttRR | ttRr |
| tr | TtRr | Ttrr | ttRr | ttrr |
Penotypes: 9 Tall Red (TTRR, TTRr, TtRR, TtRr) : 3 Tall white (TTrr, Ttrr,) : 3 Dwarf red (ttRR, ttRr) : 1 Dwarf white (ttrr)
Genotypes: 1 (TTRR) : 2 (TtRR) : 1(ttRR) : 2 (TTRr) : 4 (TtRr) : 2 (ttRr) : 1 (TTrr) : 2 (Ttrr) : 1 (ttrr)
Answer 7.
(i) Biodegradable wastes: Biodegradable wastes can be defined as wastes that can be broken down into simpler compounds by the decomposers present in the nature.
(ii) (a) Water is the raw material as well as the product in the chemical reactions of photosynthesis.
(b) Spinal cord controls mainly the reflex action. So, reflex action and involuntary action will get
disrupted. This can lead to a loss of sensory information, motor control, and coordination below the site of injury.
(iii) (a) The leaf appears green due to the presence of a green pigment called chlorophyll. When a visible light falls on chlorophyll pigment, it absorbs mainly violet, blue, red, and orange colours but reflects green colour hence chlorophyll appears green.
(b) Non – biodegradable substances cannot be degraded by microbes through biological processes to simpler forms, hence they persist in the environment for a longer period of time.
(iv)
| (a) ATP | IAA |
| Adenosine triphosphate | Indole-3-acetic acid |
| (b) Ureter | Urethra |
| Ureter carries urine from the kidneys to the urinary bladder. | Urethra carries urine from the urinary bladder to the outside of the body. |
(v) (a) 1 – Vitreous humour, 2 – Blind spot, 3 – Lens, 4 – Pupil.
(b) The defect is Myopia or near sightedness and it can be corrected by using a concave lens.
(c) Myopia corrected by concave lens is depicted in diagram shown below:
Answer 8.
(i) Cerebrospinal fluid: It is a clear, colourless, slightly alkaline fluid present in the ventricles of the brain, central canal of the spinal cord and spaces between meninges which protects the brain and spinal cord from injury and shocks.
(ii) (a) Dihybrid cross
(b) Diapedesis
(iii) (a) Sulphur dioxide
(b) Mortality.
(iv) (a) Sperms are produced in the seminiferous tubules of testes.
(b) Prostate gland
Functions:
- It secrets a milky, alkaline, and thick fluild making 20-30% of the semen volume.
- It also helps in the regulation flow of urine.
(v)
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