Oswal Model Specimen Papers ICSE Class 10 Biology Solutions (Specimen Paper - 8)

Section-A

1. (i) (b) Lacrimal gland

Explanation :

Tear glands or lacrimal glands are located at the upper sideward portion of the orbit. Six to twelve ducts of the gland pour the secretion over the front surface.

(ii) (b) Mitosis is the division of a cell into two identical daughter cells, each with the same number of chromosomes as the parent cell.

Explanation :

Mitosis is a type of cell division that occurs in somatic cells, where a single cell divides to form two identical daughter cells. It is a crucial process for growth, development, and tissue repair. During mitosis, the genetic material, organized into chromosomes, is replicated, and distributed equally between the two daughter cells. Each daughter cell receives an identical set of chromosomes to the parent cell, ensuring genetic continuity. This process is essential for maintaining the chromosome number and genetic stability in organisms.

(iii) (b) Thyroid

Explanation :

Hormone secreted by the thyroid gland regulates the basal metabolic activity of an individual.

(iv) (a) Semen will be without sperm.

Explanation :

After the production of sperms, from epididymis, they travel through the vas deferens to go into the urethra to combine with the secretions of the seminal vesicles and prostate gland called semen, if the vas deferens are surgically cut, folded, and tied, the sperm will not be able to go into the urethra and the secretions will be without sperm.

(v) (a) Evaporation of water from the leaves helps in cooling the plant.

Explanation :

When water evaporates from the surface of the leaves, it takes away heat energy from the plant, resulting in cooling. This is similar to how sweating cools our bodies. In this case, Plant A had a fan directed towards it, which increased air movement around the leaves. The increased air movement facilitated the evaporation of water from the leaves at a higher rate, leading to more cooling compared to Plant B. The water droplets observed on Plant A were a result of the evaporative cooling process, where the moisture in the leaves condensed into visible droplets. This observation supports the inference that the evaporation of water from the leaves helps in cooling the plant.

(vi) (a) Both A and R are True.

Explanation :

Turgor pressure is the pressure exerted by the fluid inside the plant cell against its cell wall. It is generated when water enters the cell through osmosis, causing the cell to swell and become rigid. The turgor pressure is responsible for maintaining the shape and firmness of plant cells, contributing to the overall rigidity of the plant.

The assertion states that turgor pressure is responsible for the rigidity and firmness of plant cells, which is correct. The reason explains that turgor pressure is generated when water enters the plant cells, causing them to swell and exert pressure on the cell wall. Therefore Both A and R are True.

(vii) (b) Interphase

Explanation :

The interphase is the metabolic phase of the cell in which it obtains nutrients and metabolizes them. Further it grows and replicates its DNA in the preparation for mitosis and conducts other normal cell functions.

(viii) (b) 65 HSU

Explanation :

The maximum permissible smoke density in diesel vehicle is 65 HSU, beyond this the vehicle is said to be pollution causing.

(ix) (a) Diving the total number of individuals living in the area by the total land area.

Explanation :

The population density can be calculated by the division of the number of people by the area occupied by them.

(x) (c) Small intestine and stimulates pancreas

Explanation :

Secretin is secreted by the pancreas to act on the small intestine. Secretin neutralizes the pH of the duodenum, allowing the digestive enzymes from the pancreas to function optimally.

(xi) (a) Retina

Explanation :

The retina is a layer of tissue located at the back of the eye. It contains specialized cells called photoreceptor cells, which include rod cells and cone cells. These photoreceptor cells are responsible for converting light into electrical signals that can be interpreted by the brain, allowing us to see. Rod cells are highly sensitive to light and are responsible for vision in low light conditions, as well as detecting motion. They are more concentrated towards the outer regions of the retina. Cone cells, on the other hand, are responsible for colour vision and visual acuity. They are most concentrated in the
central region of the retina called the fovea, which is responsible for detailed and sharp vision.

(xii) (b) Centromere

Explanation :

The point at which two sister chromatids or duplicated DNA are attached is called Centromere.

(xiii) (d) All of these

Explanation :

When we perform any intense exercise, the internal temperature of our body increases, to prevent overheating, our sweat glands present on the skin secrete sweat and the evaporation of moisture from the skin helps us cool down.

(xiv) (c) Man Rh^+ve and woman Rh^-ve

Explanation :

Erythroblastosis fetalis, also known as hemolytic disease of the newborn, is a condition that arises when there is an incompatibility between the blood types of the mother and the fetus, specifically with respect to the Rh factor. The Rh factor refers to a protein present on the surface of red blood cells. If a woman is Rh-negative (lacks the Rh factor) and the man is Rh-positive (has the Rh factor), there is a possibility of the fetus inheriting the Rh-positive blood type from the father. During pregnancy, if the fetal blood comes into contact with the mother’s blood, her immune system may produce antibodies against the Rh factor.

(xv) (a) Phototropism

Explanation :

Phototropism is the plant’s response to light, which causes the stems and other plant parts to grow towards or away from the light source. In the given scenario, the stems of the potted plants are bending towards the window where sunlight enters. This bending is a result of phototropism, as the plants are growing towards the light in order to maximize their exposure to it for photosynthesis.

2. (i) (a) Pachytene

(b) Lenticel

(d) Phytohormones

(e) Peristalsis

(ii) (a) Platelets → Thromboplastin → Thrombin → Fibrinogen → Fibrin

(b) Pinna → Malleus → Incus → Stapes → Cochlea

(d) Fertilisation → Uterus → Implantation → Gestation → Parturition

(e) Green leaves → Caterpillar → Frog → Snake → Owl

(iii) (a) Grana

(b) Iodine solution

(d) Calvin cycle

(e) Sucrose

(iv) (a) Ureter, Category: urine formation through nephron

(b) Loop of Henle, Category: parts of kidney

(d) Uterus, Category: parts of urinary system

(e) Carbon dioxide, Category: waste products in the body

(v)

Column I	Column II
(a) Autosomes	(3) Chromosome other than the pair of sex chromosomes
(b) Movement of water	(2) Xylem
(c) Bacteria and fungi	(5) decomposers
(d) 2,4-D and 2,4,5-T	(4) Eradication of weeds
(e) Coronary veins	(1) Collect deoxygenated blood from the wall of the heart

Section-B

3. (i) Meninges and pericardium

(ii) (a) Simple goitre (b) Dark reaction

(iii) (a) False, Cones are the receptor cells in the retina of the eye that are sensitive to the bright light.

(b) False, the unit of light absorbed by the chlorophyll during photosynthesis is the photon or quantum.

(iv) Nostrils → Nasal chamber → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli→ Blood capillary → RBC → Haemoglobin → Respiring tissue cell.

(v) (a) To demonstrate the role of xylem and phloem in flowering plants.

(b) In shoot A, phloem tissue has been removed. In shoot B, central xylem tissue has been removed.

(c) Plant A gets water and minerals and synthesizes its food and remains healthy. Plant B due to lack of xylem does not get its supply of water and minerals. The leaves are seen drooping and will dry.

4. (i) The function of a nephron is to filter blood and produce urine in the kidneys. Nephrons play a vital role in maintaining the body’s fluid balance, regulating electrolyte levels, and removing waste products from the blood.

(ii) (a) A man can live without food for a number of days, but he cannot survive without oxygen for more than a few minutes because food is stored in the body in various forms like proteins, glycogen, fats, etc. so the stored food material and energy can be used but oxygen is not stored in the body in any form. Hence, the deficiency of oxygen leads to asphyxiation and finally, the person dies.

(b) 1st meiotic division is the reductional division because during this division, chromosome number is reduced to half.

(iii) (a) True

(b) False

(iv) Asexual reproduction: The process of producing offspring which involves a single parent without the formation of gametes is called asexual reproduction. Yes, cell division can be considered as a type of reproduction in unicellular organisms because through cell division two or more daughter cells are produced from a parent cell.

(v)

5. (i) The function of the aqueous humour is to allow light rays to pass into the eye, prevents their refraction and dispersion, and keep the lens moist.

(ii) Gametic meiosis and Zygotic meiosis:

Gametic meiosis	Zygotic meiosis
(i) When the reproductive cells of a diploid organism undergo meiosis to produce haploid gametes, it is called Gametic meiosis.	When a diploid zygote undergoes meiosis to form haploid cells, it is called Zygotic meiosis.
(ii) These haploid gametes unite during fertilization to form diploid organisms.	The diploid zygote divides to form haploid organisms.

(iii) (a) Roots

(b) Stem

(iv) (a) Chyme: It is the semi-solid paste formed by the churning of partially digested food from the stomach mixed with gastric juice secreted by the stomach.

(b) Dialysis: It is an artificial process of removal of metabolic wastes and excess water from the body by using a machine in order to maintain the normal water and solute concentration in our body.

(v) (a) The cell shown in the diagram is in a flaccid [plasmolysed] state.

(b) Plasma membrane acts as a selectively permeable membrane.

(c) In plant cells, a cell wall, a large vacuole in the centre and chloroplasts are present which are not seen in an animal cell.

6. (i) Tears clean the front surface of our eye by removing dust particles and the enzyme lysozyme present in tears, kills the germs.

(ii) (a) Synergistically, antagonistically

(b) 72 beats per minute

(iii) (a) In honey bees, the female is diploid and the male is haploid because in honey bees, females develop from fertilized eggs which are diploid and males develop from unfertilized eggs which are haploid.

(b) The CFCs cause damage to the ozone layer which protects us from the harmful effects of ultraviolet rays present in sunlight. Hence, its use is banned in some countries.

(iv) (a) Odd: Lymphocyte; Category: Others are different types of white blood cells.

(b) Odd: Spinal cord; Category: Others are grouped under neuron structure.

(v) (a) Transpiration.

(b) The spring balance measures the weight of the test tube before and after the experiment.

7. (i) Sulphuric acid.

(ii) (a) In the cortex of kidney or in the inner lighter region of kidney.

(b) Chordae tendineae are fibrous cords or tendons that connect the papillary muscles to the atrioventricular valves (mitral and tricuspid valves) in the heart. They help to anchor the valves and prevent them from being pushed back into the atria during ventricular contraction, ensuring proper blood flow through the heart.

(iii) Decomposers act upon dead and decaying organisms and convert them into simpler forms. These simple substances get mixed up in the soil and are used as nutrients by the producers. From producers, it goes to consumers and so on. They maintain the balance in the ecosystem and provide space for new life in the ecosystem.

(iv)

(v) Parents Purple flower × White flower

(PP) (PP)

F₁ generation:

F₂ generation:

8. (i) Dust particles

(ii) (a) Green plants manufacture food during the process of photosynthesis and give out oxygen; a life supporting gas for all organisms.

(b) Loss of nucleus gives RBCs a biconcave shape thus increasing their surface area volume ratio for absorbing more oxygen. RBCs do not have mitochondria so they cannot use oxygen for themselves.

Thus, for their efficient function matured mammalian RBCs lack a nucleus and mitochondria.

(iii) (a) Kill the cells

(b) Remove chlorophyll

(iv) The three main parts of a chromosome are: the centromere, arm, and telomere.

(v) (a) The process is called osmosis.

(b) This process occurs in the root hair cells of plants.