Question 1

Question 1(b)The statements given below are False. Rewrite the correct form of the statement by changing the word which is underlined: [5](i) Alpha cells of pancreas secrete Insulin.(ii) Formalin is an example of an Antiseptic.(iii) CNG is mainly responsible for the formation of acid rain.(iv) Sulphadiazine is an example of an Antiseptic(v) Cretinism is caused due to deficiency of Adrenaline

Accepted Answer

(i) Alpha cells of pancreas secrete Glucagon.(ii) Formalin is an example of a Disinfectant.(iii) Fossil fuel is mainly responsible for the formation of acid rain.(iv) Sulphadiazine is an example of a sulphonamide.(v) Cretinism is caused due to deficiency of Thyroxine.

Question 2

Question 1(g)Rewrite and complete the following sentences by inserting the correct word in the space indicated: [5](i) The phenomenon of loss of water through a cut stem or injured part of plant is called ................(ii) ............... is the scientific name of garden pea, which Mendel used for his experiments.(iii) A fluid that occupies the larger cavity of the eye ball behind the lens is ................(iv) Oxygen combines with haemoglobin present in RBC and forms ................(v) ............... causes corrosion of the marble or brick surface.

Accepted Answer

(i) The phenomenon of loss of water through a cut stem or injured part of plant is called Bleeding.(ii) Pisum Sativum is the scientific name of garden pea, which Mendel used for his experiments.(iii) A fluid that occupies the larger cavity of the eye ball behind the lens is Vitreous humour .(iv) Oxygen combines with haemoglobin present in RBC and forms Oxyhaemoglobin.(v) Acid rain causes corrosion of the marble or brick surface.

Question 3

Question 2(a)The diagram below shows two test-tubes A and B. Test-tube A contains a green water plant. Test-tube B contains both a green water plant and a snail. Both test-tubes are kept in sunlight. Answer the questions that follow: [5](i) Name the physiological process that releases the bubbles of oxygen.(ii) Explain the physiological process as mentioned above in Q.2(a)(i).(iii) What is the purpose of keeping a snail in test-tube 'B'?(iv) Why does test-tube 'B' have more bubbles of oxygen?(v) Give an example of a water plant that can be used in the above experiment.(vi) Write the overall chemical equation for the above process.

Accepted Answer

(i) Photosynthesis(ii) 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. Plants release oxygen as a by-product during photosynthesis.(iii) The snail respires and releases Carbon dioxide so more Carbon dioxide is available to the plant for photosynthesis.(iv) Test tube B have more bubbles of Oxygen because the rate of photosynthesis is more in test tube B as the plant gets more CO2 from the snail.(v) Hydrilla is a water plant which is used for such experiments.(vi) Balanced chemical equation representing the process of photosynthesis is given below:6CO2+12H2O  ⟶chlorophylllight energy  C6H12O6+6H2O+6O2↑6CO_2 + 12H_2O \space \space \overset{	ext{light energy}}{\underset{	ext{chlorophyll}}{\longrightarrow}} \space \space C_6H_{12}O_6 + 6H_2O + 6O_2 \uparrow6CO2​+12H2​O  chlorophyll⟶​light energy​  C6​H12​O6​+6H2​O+6O2​↑

Question 4

Question 3(a)An apparatus as shown below was set up to investigate a physiological process in plants. The setup was kept in sunlight for two hours. Droplets of water were then seen inside the bell jar. Answer the questions that follow: [5](i) Name the process being studied.(ii) Explain the process named above in Q.3 (a) (i).(iii) Why was the pot covered with a plastic sheet?(iv) Suggest a suitable control for this experiment.(v) Mention two ways in which this process is beneficial to plants.(vi) List three adaptations in plants to reduce the above mentioned process.

Accepted Answer

(i) Transpiration(ii) Transpiration is the loss of water in the form of water vapour from the aerial parts of the plants like leaves, stems, etc. The water vapour is released from tiny openings called stomata, present on the aerial parts of the plant.(iii) The pot is covered with a plastic sheet to prevent evaporation of water from the soil.(iv) A control for this experiment will be an empty polythene bag with its mouth tied and kept in sunlight. It will show no droplets of water inside.(v) Transpiration is beneficial to plants in the following ways:It creates a suction force in the stem which enables the roots to absorb water and minerals.It helps in cooling the plant in hot weather.(vi) Three adaptations in plants to reduce transpiration are:Sunken stomata.Narrow leaves.Reduced exposed surface by rolling or folding of leaves.

Question 5

Question 3(b)Briefly answer the following questions: [5](i) State two reasons for the increase of population in India.(ii) What is the significance of amniotic fluid?(iii) What is the function of ear ossicles?(iv) Mention any two activities of the WHO.(v) State Mendel's law of Dominance.

Accepted Answer

(i) The two main reasons for the rapid increase of population in India are —Illiteracy — Most of the rural population which forms the bulk of our society are still illiterate, ignorant, and follow various superstitions. They also do not know the functioning of the human reproductive system.Economic reasons — Children are considered to be helping hands to increase family income.(ii) Amniotic fluid fills the space between the amnion and the embryo. It's important functions are:It keeps even pressure all around the embryo.It prevents sticking of the foetus to the amnion.(iii) The ossicles increase the intensity of the sound vibrations received by the tympanum and transmit them to the inner ear.(iv) Two activities of the WHO —To collect & supply information about occurrence of diseases of epidemic nature.To promote and support projects for research on diseases.(v) Law of Dominance — Out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed. The one that expresses is the dominant character and the one that is unexpressed is the recessive one. The recessive character can express only when the pair consists of both recessives (homozygous recessive).

Question 6

Question 4(a)The diagrams given below are cross sections of blood vessels: [5](i) Identify the blood vessels A, B and C.(ii) Name the parts labelled 1 to 3.(iii) Name the type of blood that flows through A.(iv) Mention one structural difference between A and B.(v) In which of the above vessels does exchange of gases actually take place?

Accepted Answer

(i) The blood vessels A, B, C are:A → ArteryB → VeinC → Capillary(ii) Parts labelled 1 to 3 are:1 → Connective tissue / Tunica externa2 → Lumen3 → Muscular tissue / Tunica media(iii) Oxygenated blood flows through A.(iv) Arteries have narrow lumen whereas Veins have wide lumen.(v) Capillary (i.e., blood vessel C marked above)

Question 7

Question 4(b)Differentiate between the following pairs on the basis of what is mentioned within brackets: [5](i) Diffusion and Osmosis (Definition)(ii) RBC and WBC (Shape)(iii) Tubectomy and Vasectomy (Part cut and tied)(iv) Vasopressin and Insulin (Deficiency disorder)(v) Rods and Cones of Retina (Type of pigment).

Accepted Answer

(i) Difference between Diffusion and Osmosis (Definition)DiffusionOsmosisDiffusion is the free movement of molecules of a substance from the region of their higher concentration to the region of their lower concentration when the two are in a direct contactOsmosis is the movement of water molecules from their region of higher concentration (dilute solution or with a lower solute concentration) to their region of lower concentration (concentrated solution or with a higher solute concentration) through a semi permeable membrane.(ii) Difference between RBC and WBC (Shape)RBCWBCRBCs are biconcave disc-like structures, flat in the centre and thick and rounded at the periphery.WBCs have irregular amoeboid shape and can produce pseudopodia.(iii) Difference between Tubectomy and Vasectomy (Part cut and tied)TubectomyVasectomyOviducts / Fallopian tubesSperm ducts/ Vas deferens(iv) Difference between Vasopressin and Insulin (Deficiency disorder)VasopressinInsulinDiabetes insipidusDiabetes mellitus(v) Difference between Rods and Cones of Retina (Type of pigment).RodsConesRhodopsinIodopsin

Question 8

Question 5(b)Draw neat and labelled diagrams of the following: [5](i) Malpighian Capsule.(ii) A Myelinated Neuron.

Accepted Answer

(i) Below labelled diagram shows Malpighian Capsule:(ii) Below labelled diagram shows a Myelinated Neuron:

Question 9

Question 6(a)The diagram given below shows the male urinogenital system of a human being. Study the diagram and answer the questions that follow: [5](i) Label the parts numbered 1 to 8.(ii) Name the corresponding structure of part (4) in female reproductive system.(iii) What is the role of part 7?

Accepted Answer

(i) The parts numbered 1 to 8 are:1 → Urinary bladder2 → Ureter3 → Prostate gland4 → Vas deferens / Sperm duct5 → Urethra6 → Testis7 → Scrotum / Scrotal sac8 → Epididymis(ii) Fallopian tube / Oviduct(iii) Scrotum is a thin-walled sac of skin that protects and surrounds the testes. It also maintains the temperature of testes at 2 to 3°C less than body temperature for the maturation of sperms.

Question 10

Question 6(b)In a homozygous plant round seeds (R) are dominant over wrinkled seeds (r): [5](i) Draw a Punnett square to show the gametes and offspring when both the plants have heterozygous round seeds (Rr).(ii) Mention the Phenotype and Genotype ratios of the offsprings in F2 generation.(iii) Name the sex chromosomes in human males and females.(iv) Briefly explain the term 'Mutation'(v) What is the number of chromosomes in the gametes of human beings?

Accepted Answer

(i) Below is the Punnett square board showing the gametes and offspring when both the parents have heterozygous round seeds: RrRRRrRrRrrr(ii) Phenotype and Genotype ratios of the offsprings in F2 generation are: Phenotype Ratio — 3 : 1Genotype Ratio — 1 : 2 : 1(iii) Sex chromosomes in human males and females are:Males — XYFemales — XX(iv) Mutation — Mutation is a sudden change in one or more genes, or in the number or in the structure of chromosomes. Mutation alters the hereditary material of an organism's cells and results in a change in certain characters or traits in an entire population and such changes can persist for years.(v) Human gametes have 23 chromosomes.

Question 11

Question 7(a)The diagram below represents the human heart in one phase of its functions. Study the diagram carefully and answer the questions that follow: [5](i) Name the phase.(ii) Which part of the heart is contracting in this phase? Give a reason to support your answer.(iii) Name the parts labelled 1 to 4.(iv) What type of blood flows through '2'?(v) State the function of the part numbered '5'.(vi) Name the membrane that covers the heart.

Accepted Answer

(i) Ventricular Systole.(ii) Ventricle is contracting because both tricuspid and bicuspid valves are closed whereas both pulmonary semi-lunar and Aortic semi-lunar valves are open to pump the blood out of the two ventricles.(iii) The parts labelled 1 to 4 are:1 → Pulmonary Artery2 → Aorta3 → Bicuspid/Mitral valve4 → Aortic Semilunar valve(iv) Oxygenated blood(v) Part numbered '5' are the Pulmonary Semilunar valves. They allow the deoxygenated blood to flow from the right ventricle to the lungs and prevents its backflow.(vi) Pericardium

Question 12

Question 7(b)Explain the following terms: [5](i) Greenhouse effect.(ii) Turgor pressure.(iii) Selective reabsorption.(iv) Natality.(v) Pulse.

Accepted Answer

(i) The phenomenon by which certain gases specially CO2 and methane (CH4) accumulating in the atmosphere prevent the escape of heat, thereby warming the earth’s surface is known as Greenhouse effect.(ii) The pressure of the cell contents on the cell wall is called Turgor pressure.(iii) The glomerular filtrate entering the renal tubule is an extremely dilute solution containing a lot of useful materials such as glucose and some salts such as those of sodium. As this filtrate passes down the renal tubule, a lot of water along with these usable materials is reabsorbed. But their reabsorption is only to the extent that the normal concentration of the blood is not disturbed. This is called Selective Absorption.(iv) Natality is the number of live births per thousand people per year.(v) Pulse is the alternate expansion and elastic recoil of the wall of the artery during ventricular systole.

Solved 2015 Question Paper ICSE Class 10 Biology

Section I 40 Marks

Section Ii 40 Marks