Question 1

Question 2(a)The diagram given below represents an experiment to prove the importance of a factor in photosynthesis. Answer the questions that follow:(i) Which factor is being studied here?(ii) What is the purpose of keeping KOH in the flask?(iii) Explain the term Photosynthesis.(iv) What will you observe when the leaf A is tested for starch?(v) Write a well balanced chemical equation for the process of photosynthesis.

Accepted Answer

(i) Factor being studied here is necessity of Carbon dioxide for photosynthesis.(ii) KOH absorbs carbon dioxide.(iii) Photosynthesis is the process by which living plant cells, containing chlorophyll, produce food substances (glucose and starch), from carbon dioxide and water, by using light energy and release oxygen as a by-product.(iv) The part of leaf inside the flask will not turn blue while the part of leaf outside the flask will turn blue showing the presence of starch. This proves that photosynthesis did not occur in the leaf portion inside the flask where carbon dioxide was absent.(v) Balanced chemical equation representing the process of photosynthesis is given below:6CO2+12H2O→chlorophylllight energyC6H12O6+6H2O+6O2↑6	ext{CO}_2 + 12	ext{H}_2	ext{O} \xrightarrow[	ext{chlorophyll}]{	ext{light energy}} 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6	ext{H}_2	ext{O} + 6	ext{O}_2 \uparrow6CO2​+12H2​Olight energychlorophyll​C6​H12​O6​+6H2​O+6O2​↑

Question 2

Question 2(b)The diagram given below represents the simplified pathway of the circulation of blood. Answer the questions that follow:(i) Name the blood vessels labelled 1 to 4.(ii) Which blood vessel supplies oxygenated blood to the muscles of the heart?(iii) What is the importance of blood vessel labelled 5?(iv) What is the type of blood circulation that takes place between the heart and the lungs?(v) Draw a diagram of the different blood cells as seen in a smear of human blood.

Accepted Answer

(i)1 → Anterior vena cava2 → Aorta3 → Pulmonary artery4 → Pulmonary vein(ii) Coronary Artery(iii) Blood vessel labelled as 5 is the hepatic portal vein. It serves as a critical connection between the digestive system and the liver, allowing for nutrient processing, detoxification, and regulation of various metabolic functions.(iv) Pulmonary circulation(v) Below diagram shows the different blood cells as seen in a smear of human blood:

Question 3

Question 3(a)The diagram given below depicts a defect of the human eye which has been corrected by using a suitable lens. Answer the following questions:(i) Name the defect that has been corrected. Which type of lens has been used for the correction?(ii) Mention one cause for the above defect.(iii) Where would the image have formed if the above lens was not used for correction?(iv) Name the three concentric layers of the eyeball.(v) Draw a neat, labelled diagram of a neuron.

Accepted Answer

(i) Myopia is the defect that has been corrected. Concave lens has been used.(ii) Lens is too curved.(iii) The image would have been formed in front of retina if the above lens was not used for correction.(iv)Outer- ScleraMiddle- ChoroidInner - Retina(v) Diagram of a neuron with the parts labelled is shown below:

Question 4

Question 3(b)Give the biological reasons for the following statements:(i) It is advisable to keep green plants in an aquarium.(ii) Water pollution is a major cause of concern in our country.(iii) We cannot distinguish colours in dim light.(iv) Medical discoveries such as antibiotics and vaccinations have indirectly contributed to the sharp rise in human population.(v) Homo sapiens sapiens is the most highly evolved form of man.

Accepted Answer

(i) Green plants release oxygen which dissolves in the water. This oxygen is used by fish in the aquarium. Therefore, to maintain the oxygen level in the water it is advisable to keep green plants in an aquarium.(ii) India has the world's largest population but has only 4% of the world's freshwater resources. Pollution of water bodies, such as rivers, lakes, and groundwater is rapidly depleting these limited reserves leading to an acute shortage of clean water for domestic, agricultural, and industrial use.(iii) We cannot distinguish colours in dim light because the cone cells, responsible for vision of colours are sensitive only to bright light.(iv) Medical discoveries such as antibiotics and vaccinations have lowered death rate by treatment and prevention of deadly diseases, thus, indirectly contributing to the sharp rise in human population.(v) Homo sapiens sapiens is the most highly evolved form of man as they possess the following main characteristics:Bipedal locomotion.Cranial capacity ranging from 1450 to 1600 cm3 and a much enlarged cerebrum.Prominent chin, snout disappeared.Highly reduced body hair.

Question 5

Question 4(a)The figure given below shows a part of a nephron.Answer the questions that follow:(i) In which region of the kidney is the above structure present?(ii) Label the parts numbered 1 to 4.(iii) What is the technical term for the process that occurs in part 3?(iv) Why is fluid X not called urine? Justify your answer.(v) Draw a neat, labelled diagram of the urinary system of man.

Accepted Answer

(i) Cortex(ii) Parts numbered 1 to 4 are:1 → Afferent arteriole2 → Efferent arteriole3 → Glomerulus4 → Bowman's capsule(iii) Ultrafiltration(iv) Fluid X is called glomerular filtrate and not urine because it contains almost all the liquid part of the blood i.e., plasma along with most of its organic and inorganic substances including urea, glucose, amino acids, etc. These substances, along with water, are reabsorbed before urine is formed.(v) Labelled diagram of the urinary system is shown below:

Question 6

Question 4(b)Differentiate between the following pairs on the basis of what is mentioned in the brackets:(i) Transpiration and Guttation (place of occurrence)(ii) Biodegradable waste and Non-biodegradable waste (One example)(iii) Population control and Swachh Bharat Abhiyan (One objective)(iv) Osmosis and Active Transport (Substances undergoing movement)(v) Metaphase and Anaphase (Position of chromosomes)

Accepted Answer

(i) Transpiration occurs through the stomata from leaves while guttation occurs through hydathodes from leaf tip.(ii) Leaves are biodegradable waste while plastic is non-biodegradable waste.(iii) Population control aims at lowering the growth rate of population and Swachh Bharat Abhiyan aims at cleanliness in surrounding.(iv) In osmosis, there is movement of solvent or water but in active transport there is movement of ions or salt particles.(v) In metaphase, the chromosomes are arranged in equatorial plane while in anaphase the chromosomes are moved toward poles.

Question 7

Question 5(a)The diagram below represents an experiment to demonstrate a certain phenomenon in a green plant:(i) Will the level of mercury in the glass tubing rise or fall? Which conducting tissue of the plant does the glass-tubing represent?(ii) Define Transpiration.(iii) How will the rate of the above process differ if the environment of the plant has:Less humidityHigh temperature?(iv) State any two advantages of transpiration to the plant.(v) Draw a neat labelled diagram of a Plasmolysed cell.

Accepted Answer

(i) The level of mercury in the glass tubing will rise. The glass-tubing represents xylem.(ii) Transpiration is the loss of water in the form of vapour from the aerial parts of the plant.(iii)Less humidity increases the rate of transpiration.High temperature increases the rate of transpiration.(iv) Two advantages of transpiration to the plants are:Cooling effect.Creation of suction force for ascent of sap.(v) Labelled diagram of a plasmolysed cell is given below :

Question 8

Question 5(b)Give appropriate biological technical terms for the following:(i) The sensory organ in Cochlea.(ii) Number of live births per 1000 people per year.(iii) The point of contact between two neurons.(iv) The accessory gland in human males whose secretion neutralises the acid in the vagina.(v) Condition when blood sugar level is lowered in the blood.(vi) Structure which helps in the adjustment of the size of the pupil.(vii) A surgical method of fertility control in human males.(viii) Process by which leucocytes migrate through the walls of capillaries.(ix) A sudden inheritable change in one or more genes.(x) A non-dividing phase of the cell cycle where more DNA is synthesised.

Accepted Answer

(i) Organ of Corti(ii) Birth rate(iii) Synapse(iv) Prostate gland(v) Hypoglycemia(vi) Iris(vii) Vasectomy(viii) Diapedasis(ix) Mutation(x) Synthesis Phase (S)

Question 9

Question 6(a)State two functions of:(i) Ear(ii) Ethylene(iii) Tears(iv) Testis(v) Cerebellum

Accepted Answer

(i) Two functions of Ear:HearingBalancing(ii) Two functions of Ethylene:Acceleration of senesenceRipening of fruits(iii) Two functions of Tears:LubricationAntibacterial due to presence of lysozyme(iv) Two functions of Testis:Sperm formation (spermatogenesis)Production of Testosterone(v) Two functions of Cerebellum:Maintain balance of the body.Coordinate muscular activity.

Question 10

Question 6(b)Complete the table:Name of the HormoneEndocrine GlandFunction(i)(ii)Deposits extra glucose of blood as glycogenGrowth Hormone(iii)(iv)(v)Thyroid(vi)(vii)(viii)Prepare body for any emergencyOxytocin(ix)(x)

Accepted Answer

Name of the HormoneEndocrine GlandFunction(i) Insulin(ii) Beta-cells (pancreas)Deposits extra glucose of blood as glycogenGrowth Hormone(iii) Anterior Pituitary(iv) Normal growth of body(v) ThyroxineThyroid(vi) regulates basal metabolism(vii) Adrenaline(viii) AdrenalPrepare body for any emergencyOxytocin(ix) Posterior pituitary(x) Stimulates vigorous contractions of uterus in a pregnant mother, leading to childbirth

Question 11

Question 7(a)A homozygous dominant tall pea plant bearing red flowers (TTRR) is crossed with a homozygous recessive dwarf pea plant bearing white flowers (ttrr).(i) What is the phenotype and genotype of F1 individuals?(ii) Write the possible combination of gametes that are obtained when two F1 hybrid plants are crossed.(iii) Mention the phenotypic ratio of the F2 generation.(iv) State Mendel's Law of Independent Assortment.(v) Name two X-linked disorders found in humans.

Accepted Answer

(i) Phenotype - All plants will be Tall and will bear red flowers.Genotype - TtRr(ii) TR, Tr, tR, tr(iii) 9:3:3:1(iv) Law of Independent Assortment, states that when there are two pairs of contrasting characters, the distribution of the members of one pair into the gametes is independent of the distribution of the other pair.(v) Colour-blindness and Haemophilia

Question 12

Question 7(b)The diagram given below is that of a developing human foetus. Answer the questions that follow:(i) Label the parts numbered 1 to 3 in the diagram.(ii) Mention any two functions of the part labelled 2 in the diagram.(iii) Explain the significance of the part numbered 3 in the diagram.(iv) Define the term 'Gestation'. What is the normal gestational period of the developing embryo?(v) Mention the sex chromosomes in a male and female embryo.

Accepted Answer

(i) Parts numbered 1 to 3 are:1 → Umbilical cord2 → Placenta3 → Amniotic fluid(ii) Function of placenta are:Passes nutrients and respiratory gases to foetus from mother.Acts as endocrine gland, secretes oestrogen and progesterone.(iii) Amniotic fluid protects the embryo from physical damage by jerk. It keeps an even pressure all around the foetus. It also permits restricted movement to foetus.(iv) The full term of the development of the embryo in the uterus is called gestation. The normal gestational period of the developing embryo is 280 days.(v) Male — XY.     Female — XX.

Solved 2020 Question Paper ICSE Class 10 Biology