Oswal Model Specimen Papers ICSE Class 10 Biology Solutions (Specimen Paper - 7)


1. (i) (a) Open stomata, dry atmosphere, and moist soil.

Explanation :    

Transpiration pull will be maximum in this condition because the stomata are open for the water to dry out, atmosphere needs water from the plants due to dry atmosphere and the soil has plenty water to supply during transpiration.

(ii) (d) Dura mater

Explanation :    

Brain is covered with three layers: the outer most is called dura mater, the innermost layer is called pia mater and the middle one is known as arachnoid layer.

(iii) (d) Iodine

Explanation :    

Iodine enables the thyroid gland to produce T4 and T3 hormones.

(iv) (c) Two cerebral hemispheres

Explanation :    

Corpus callosum is the fluid present between the two hemispheres of the brain, connecting them.

(v) (a) Ovulation

Explanation :    

Ovulation is the release of the egg from the Graafian follicle and converting it into corpus luteum.

(vi) (c) Both A and R are true.

Explanation :    

The assertion states that photosynthesis is the process by which plants convert sunlight into chemical energy, which is true. The reason supports this assertion by explaining that during photosynthesis, plants use chlorophyll and other pigments to capture light energy, which is then converted into
chemical energy in the form of starch. This explanation aligns with the overall understanding of photosynthesis and its role in energy production for plants.

(vii) (b) Turgor pressure

Explanation :    

Turgor pressure is the pressure exerted by the water and cell content present inside the cell on the wall of the cell.

(viii) (a) Centriole

Explanation :    

Centrioles form spindle fibres from opposite poles of the cell that connect to the chromosomes at their centromere.

(ix) (c) S-phase

Explanation :    

S-phase is the synthesis phase where DNA replication takes place and DNA doubles.

(x) (a) It allows for the transfer of genetic material between different individuals, leading to increased genetic diversity.

Explanation :    

Cross-pollination in plants enables the transfer of genetic material between different individuals, enhancing genetic diversity. This diversity aids plants in adapting to environmental changes and resisting diseases and pests. It introduces new genetic variations, improving traits like disease resistance and productivity. The survival and evolution of plant species are also facilitated by this genetic variability. In the case of the gardener’s tomato plants, cross-pollination can potentially increase the genetic diversity of the offspring, addressing the issue of low fruit production and improving yield.

(xi) (c) Neurons have a complex structure with multiple specialized components, including dendrites, cell body, axon, and synaptic terminals.

Explanation :    

Neurons are highly specialized cells in the nervous system, and their structure is indeed complex. They consist of several distinct components, including dendrites, which receive signals from other neurons or sensory receptors; the cell body, which contains the nucleus and other essential organelles; the axon, a long extension that transmits signals away from the cell body; and synaptic terminals, which are responsible for transmitting signals to other neurons or target cells. This complex structure allows neurons to perform their crucial functions in transmitting and processing information in the nervous system. Option (a) is incorrect because it oversimplifies the structure by neglecting the presence of dendrites and synaptic terminals. Option (b) is also incorrect as glial cells provide support and nourishment to neurons, but they do not primarily compose the structure of neurons. Option (d) is incorrect as the structure of neurons is not primarily responsible for hormone production and secretion; that function is typically carried out by endocrine glands.

(xii) (b) Passage of water and solutes in and out of the cell

Explanation :    

The plasma membrane, also known as the cell membrane, controls the passage of water and solutes in and out of the cell. It is selectively permeable, meaning it allows certain substances to pass through while restricting the movement of others.

The structure of the plasma membrane consists of a phospholipid bilayer embedded with various proteins. The phospholipids have hydrophilic (water-attracting) heads and hydrophobic (water repelling) tails. This arrangement forms a barrier that separates the inside of the cell from the external environment.

(xiii) (a) Implementing strict regulations and monitoring systems to control nutrient runoff from agricultural fields.

Explanation :    

Excessive nutrient runoff from nearby agricultural fields is identified as the primary cause of eutrophication. Implementing strict regulations and monitoring systems to control this nutrient runoff is a proactive approach to addressing the problem at its source. By regulating the use of fertilizers and implementing proper agricultural practices, the nutrient input into the lake can be reduced, which can help mitigate eutrophication and its associated impacts on water quality and ecosystems.

(xiv) (d) Helps to overcome apical dominance

Explanation :    

Ethylene does not help to overcome apical dominance. Apical dominance is the phenomenon where the growth of the main, central stem of a plant is favoured over the lateral branches. Ethylene primarily functions in promoting senescence (aging) and abscission (shedding) of plant organs, breaking seed and bud dormancy, and hastening fruit ripening. It does not play a significant role in overcoming apical dominance, which is regulated by other plant hormones like auxins.

(xv) (b) The father’s genetics and the presence of a specific chromosome in his sperm determine the sex of the child.

Explanation :    

The sex of a child is determined by the genetic information present in the father’s sperm. Sperm cells carry either an X or Y chromosome, while egg cells from the mother always contain an X chromosome. If an X-carrying sperm fertilises the egg, the resulting child will be female (XX), and if a Y-carrying sperm fertilises the egg, the child will be male (XY). This biological process demonstrates that the father’s genetics and the specific chromosome present in his sperm determine the sex of the child.

2. (i) (a) Auxin

(b) Shoot

(c) Light and water

(d) Rhizobium

(e) Testes

(ii) (a) Stimulus, Receptor, Spinal cord, Effector, Response.

(b) Root hair, Epidermis, Cortex, Endodermis, Xylem.

(c) Conjunctiva, Aqueous humour, Pupil, Vitreous humour, Yellow spot.

(d) Soil water, Root hair, Cortical cells, Endodermis, Xylem

(e) Artery, Arteriole, Capillaries, Venule, Vein.

(iii) (a) cell

(b) Diffusion

(c) Mitochondria

(d) Endocytosis

(e) Endoplasmic reticulum

(iv) (a) Oxidation; Category: Process related to the movement of substances.

(b) Diabetes insipidus; Category: Term related to glucose metabolism.

(c) Xerophthalmia; Category: Disease caused due to shape of cornea.

(d) Ureter; Category: Part of female reproductive system.

(e) Scurvy; Category: Disease caused by hyposecretion of thyroid hormone.


Column I Column II
(a) Melting of permafrost (4) Release of methane
(b) Stomata (5) Photosynthesis
(c) Pituitary (1) Stimulates skeletal growth
(d) Oval window (2) Transfers vibrations from a bone to fluid
(e) Census (3) Counting of population


3. (i) The adrenal glands are located on top of both kidneys in the form of caps.

(ii) (a) Utriculus and sacculus

(b) Fibrinogen

(iii) (a) Isotonic solution

(b) Biodegradable waste

(iv) Alleles: Alleles are alternative forms of the same gene. For example, tallness and dwarfness are the two alternative forms of a gene for height and are called alleles. Similarly, attached ear lobes and free ear lobes are alleles for the type of ear lobes.

(v) (a) Air pollution

(b) Gases emitted from factories, industries, and automobile exhausts.

(c) Air pollution causes respiratory problems and lung disorders like bronchitis. It also leads to poor visibility and asthma.

4. (i) Nitrification : The process of converting ammonia into nitrite and nitrates by the action of micro organisms in the soil, is called nitrification.

(ii) (a) The Lacrimal glands are located above the outer corner of each eye, in the upper outer part of the eye socket. They produce tears that help keep the eyes lubricated and remove foreign particles.

(b) Hydathodes are specialized openings or pores found primarily on the leaves of plants. They are commonly located at the tips or margins of leaves and allow for the release of excess water in the form of droplets.


Immigration Emigration
(a) The movement of individuals into the population is known as immigration. The movement of individuals out of the population is known as emigration.
(b) It results in an increase in the population. It results in a decrease in the population.

(iv) (a) Submerged aquatic plants

(b) Air pollution

(v) (a) The region labelled as A is Synapse. It is a gap between two neurons where dendrites of one neuron meet the axon of the next neuron, but they never unite as there is no continuity between the nerve cells.

(b) Acetylcholine in A helps to fulfill the transmission of impulse from the axon of one neuron to the dendrites of other neurons.

(c) There are three types of neurons found in the human body. They are:

  1. Sensory neuron
  2. Motor neuron
  3. Interneuron

5. (i) Tricuspid valve is located between the right the auricle and the right ventricle.

(ii) The bicuspid valve is located between the left atrium and left ventricle of the heart. And the function of the bicuspid valve is that it prevents the backflow of blood from the left ventricle into the right.

(iii) (a) Zygote → morula → blastocyst → embryo → foetus.

(b) Hypothalamus → thyroid releasing hormone → pituitary → TSH → thyroid gland → thyroxine.

(iv) Natality and Mortality:

Natality Mortality
It is the number of offspring produced per year per 1000 of the living population. It is the number of deaths per year per 1000 living population.



6. (i) NADPH

(ii) (a) Cerebrum

(b) Centriole

(iii) Transpiration and Evaporation

Transpiration Evaporation
Loss of water in the form of vapour from aerial parts of the plant. Loss of water from the surface of the water bodies in the form of vapour.

(iv) The fully grown human embryo respires because the dissolved oxygen in the mother’s blood diffuses into the embryo and is used in the oxidation of glucose in the cells with the liberation of energy.

However, there are no breathing movements as the lungs lie collapsed in the embryo and only function after the foetus is expelled from the mother’s body.

(v) (a) Myopia or short-sightedness

(b) The eyeball has lengthened from front to back.

(c) This eye defect can be corrected by a suitable concave lens.

7. (i) Acid rain or any other form of precipitation that is unusually acidic: It is caused by the emission of sulphur dioxide and nitrogen oxides that react with water molecules in the atmosphere to form acids.

(ii) (a) Between the posterior surface of the urinary bladder and the rectum.

(b) On top of each kidney as a cap.

(iii) Hormone : A hormone is defined as a chemical substance produced by the endocrine glands situated in one part of the body and carried by the blood to some other parts of the body in order to exert its regulation and coordination effect on the cells of a specific organ or tissue.

(iv) (a) Denitrifying bacteria

(b) Grana

(v) (a) It is a longitudinal section kidney.

(b) 1 – Renal artery, 2 – Renal vein, 3 – Ureter, 4 – Medulla, 5 – Cortex, 6 – Pyramid, 7 – Pelvis, 8 –Papilla.

(c) The Renal artery carries blood containing nitrogenous wastes and more water which is lower in case of the renal vein. Renal artery carries oxygenated blood whereas the renal vein carries deoxygenated blood.

8. (i) Air pollution.

(ii) Deficiency of vitamin A causes night blindness because the visual purple (Rhodopsin) of the rods, which are responsible for vision in the dark, is not formed in the absence of vitamin A.

(iii) Carrying capacity : The maximum number of individuals that an environment can support without undergoing any deterioration is called the carrying capacity. Available space, water, resources etc.,
determine it.
(iv) Oxytocin : It stimulates uterine contractions during childbirth and causes the ejection of milk from mammary glands.

Prostate gland : It secrets alkaline fluid into the semen. This fluid neutralizes the acidity of urine in the urinogenital canal.


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