Question 1

Question 1(f)Given below is a diagram depicting a defect of the human eye, study the same and then answer the questions that follow: [5](i) Name the defect shown in the diagram.(ii) What are the two possible reasons that cause this defect?(iii) Name the type of lens used to correct this defect.(iv) With the help of a diagram show how the defect shown above is rectified using a suitable lens.

Accepted Answer

(i) Myopia / short sightedness.(ii) Two possible reasons that cause Myopia are:Eye ball is lengthened from front to back.Lens is too curved / rounded(iii) Concave lens(iv) Below diagram shows how a concave lens can be used to rectify Myopia:

Question 2

Question 2(a)The figure given below is a diagrammatic representation of a part of the cross section of the root in the root hair zone. Study the same and then answer the questions that follow: [5](i) Name the parts indicated by the guidelines 1 to 4.(ii) Which is the process that enables the passage of water from the soil into the root hair?(iii) Name the pressure that is responsible for the movement of water in the direction indicated by the arrows. Define it.(iv) Due to an excess of this pressure sometimes drops of water are found along the leaf margins of some plants especially in the early mornings. What is the phenomenon called?(v) Draw a well labelled diagram of the root hair cell as it would appear if an excess of fertiliser is added to the soil close to it.

Accepted Answer

(i) The parts indicated by the guidelines 1 to 4 are:1 → Root hair cell2 → Soil Water3 → Xylem vessel4 → Cortex cells(ii) Osmosis.(iii) Root pressure is responsible for the movement of water in the direction of the arrows. Root pressure is built up due to cell-to-cell osmosis in the root tissue. As one turgid cell presses the next cell, the force of the flow of water increases inwards.(iv) Guttation.(V) Below is the diagram showing the root hair cell with an excess of fertiliser added to the soil close to it:

Question 3

Question 2(b)Differentiate between the following pairs on the basis of what is mentioned within brackets: [5](i) Human skin cell and Human ovum (number of chromosomes)(ii) Sperm duct and fallopian tube (function)(iii) Red Cross and WHO (one activity)(iv) Rod cells and cone cells (pigment)(v) LUBB and DUP (names of the valves whose closure produce the sound)

Accepted Answer

(i) Difference between Human skin cell and Human ovum (number of chromosomes)Human skin cellHuman ovumHuman skin cell contains 46 chromosomesHuman ovum contains 23 chromosomes.(ii) Difference between Sperm duct and fallopian tube (function)Sperm ductFallopian tubeTransports sperms from testis to urethraTransports Ovum into uterus. Fertilization takes place here and then zygote travels down into uterus via the Fallopian tubes (Oviduct)(iii) Difference between Red Cross and WHO (one activity)Red CrossWHOIt procures and supplies blood for the victims of war and other calamities.It promotes and supports projects for research on diseases.(iv) Difference between Rod cells and Cone cells (pigment)Rod cellsCone cellsRhodopsin / Visual PurpleIodopsin / Visual Violet(v) Difference between LUBB and DUP (names of the valves whose closure produce the sound)LUBBDUPBicuspid and tricuspid valvesSemilunar valves.

Question 4

Question 3(a)Given below is the outline of the human body showing the important glands: [5](i) Name the glands marked 1 to 4.(ii) Name the hormone secreted by part 2. Give one important function of this hormone.(iii) Name the endocrine part of the part numbered 3.(iv) Why is the part labelled 1 called the master gland? Which part of the forebrain controls the gland labelled 1?(v) Name the gland that secretes the 'emergency hormone'.

Accepted Answer

(i) The glands 1 to 4 are:1 → Pituitary gland2 → Thyroid gland3 → Pancreas4 → Adrenal gland(ii) The hormone secreted by part 2 is Thyroxine.Thyroxine controls the basal metabolic rate (BMR) of the body. It also influences the general growth of the body, ossification of bone, body temperature, mental development.(iii) Islet of Langerhans.(iv) The part labelled 1 (i.e., the Pituitary gland) is called the master gland as it controls the secretion of other glands. Hypothalamus controls the Pituitary gland.(v) Adrenal medulla (part of Adrenal gland)

Question 5

Question 3(b)The diagram of an apparatus given below demonstrates a particular process in plants. Study the same and answer the questions that follow: [5](i) Name the apparatus.(ii) Which phenomenon is demonstrated by this apparatus?(iii) Explain the phenomenon mentioned in (ii) above.(iv) State two limitations of using this apparatus.(v) What is the importance of the air bubble in the experiment?(vi) Name the structures in a plant through which the above process takes place.

Accepted Answer

(i) Ganong's Potometer(ii) Transpiration(iii) It is the loss of water as water vapour from the aerial parts of the plant.(iv) Two limitations of using Ganong's Potometer are:Introducing the air bubble is not very easy.The twig may not remain fully alive for a long time.(v) The movement of the air bubble gives the volume of water lost in a given time.(vi) Stomata, Lenticels, Cuticle.

Question 6

Question 4(a)(i) Draw a well labelled diagram of the membranous labyrinth found in the inner ear. [5](ii) Based on the diagram drawn above in (i) give a suitable term for each of the following descriptions:The sensory cells that helps in hearing.The part that is responsible for static balance of the body.The membrane covered opening that connects the middle ear to the inner ear.The fluid present in the middle chamber of cochlea.The structure that maintains dynamic equilibrium of the body.

Accepted Answer

(i) Below labelled diagram shows the membranous labyrinth found in the inner ear:(ii) The suitable terms for the descriptions are given below:Organ of CortiUtriculus and sacculus.Oval window / Round windowEndolymphSemi-circular canals

Question 7

Question 5(a)The given diagram shows a stage during mitotic division in an animal cell: [5](i) Identify the stage. Give a reason to support your answer.(ii) Draw a neat labelled diagram of the cell as it would appear in the next stage. Name the stage.(iii) In what two ways is mitotic division in an animal cell different from the mitotic division in a plant cell?(iv) Name the type of cell division that occurs during:      A. Growth of a shoot      B. Formation of pollen grains

Accepted Answer

(i) Prophase.Chromosomes have duplicated as paired chromatids connected by centromere. Centrosome split into centrioles and are moving to opposite poles. Nuclear membrane and nucleolus disappearing.(ii) The next stage is Metaphase. It's diagram is shown below:(iii) Two differences between mitotic division in an animal cell and plant cell are:Animal cellPlant cellAsters are formed.Asters are not formed.Cytokinesis by formation of furrow in the cytoplasm.Cytokinesis by cell plate formation.(iv) Type of cell division is mentioned below:      A. Mitosis      B. Meiosis

Question 8

Question 5(b)Give scientific reasons for the following statements: [5](i) Colour blindness is more common in men than in women.(ii) Injury to medulla oblongata leads to death.(iii) When an ovum gets fertilized, menstrual cycle stops temporarily in a woman.(iv) Mature erythrocytes in humans lack nucleus and mitochondria.(v) Blood flows in arteries in spurts and is under pressure.

Accepted Answer

(i) Colour blindness is more common in men than in women because the genes responsible for the color blindness are located on the X chromosome. Males have only one X chromosome whereas females have two X chromosomes. In males, only one defective X chromosome is enough to cause colour blindness. In females, two defective X chromosomes are required to cause colour blindness. This type of inheritance pattern is called X-linked inheritance and it primarily affects males.(ii) It regulates involuntary movements such as breathing, respiration, circulation, the function of blood vessels etc. Thus, injury to medulla oblongata leads to death.(iii) When ovum gets fertilized, the corpus luteum continues to release progesterone and so keeps the uterus in a state suitable for implantation. The endometrium gets thickened, and vascularized to house the embryo. The fertilised egg implants itself in the endometrial lining of the uterus and gets fixed in it. This causes the menstrual cycle to stop temporarily.(iv) The presence of nucleus would occupy space and reduce the oxygen carrying capacity. The nucleus is also not required as a mature RBC does not divide. Mitochondria is absent so that oxygen is not utilised by the RBC and all the oxygen is transported to target areas.(v) As the ventricles of the heart contracts, they push the blood into the small lumen of the arteries with a great force, thus making the blood in the arteries flow in spurts and under pressure.

Question 9

Question 6(a)The diagram given below is that of a developing human foetus. Study the diagram and then answer the questions that follow: [5](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 human embryo?(v) Mention the sex chromosomes in a male and female embryo.

Accepted Answer

(i) The parts numbered 1 to 3 in the diagram are:1 → Umbilical cord2 → Placenta3 → Amniotic fluid(ii) Two functions of Placenta are:Acts as a barrier and prevents germs from entering foetal blood.Secretes Oestrogen and Progesterone.(iii) Protects the embryo from physical damage by jerks or mechanical shocks, keeps an even pressure all around the embryo and allows the foetus some restricted movement.(iv) The full term of the development of the embryo in the uterus is called gestation. In humans, it lasts for about 280 days / 40 weeks.(v) The sex chromosomes in a male and female embryo are:Male - XYFemale - XX

Question 10

Question 6(b)The following diagram demonstrates a physiological process taking place in green plants. The whole set up was placed in bright sunlight for several hours. Study the diagram and answer the questions that follow: [5](i) What aspect of the physiological process is being examined?(ii) Explain the physiological process mentioned in (i) above.(iii) Label the parts numbered 1 and 2 in the diagram.(iv) Write a well-balanced chemical equation for the physiological process explained in (ii) above.(v) What would happen to the rate of bubbling of the gas if a pinch of sodium bicarbonate is added to the water in the beaker? Explain your answer.

Accepted Answer

(i) The aspect being examined is the release of Oxygen during 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 parts numbered 1 and 2 are:1 → Oxygen2 → Hydrilla plant(iv) 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​↑(v) Sodium bicarbonate releases carbon dioxide into the water which is made available to the plant. This increases the rate of photosynthesis. So more oxygen is released thus more bubbles are released.

Question 11

Question 7(a)A homozygous tall plant (T) bearing red coloured (R) flowers is crossed with a homozygous dwarf (t) plant bearing white (r) flowers : [5](i) Give the genotype and phenotype of the plants of F1 generation.(ii) Mention the possible combinations of the gametes that can be obtained from the F1 hybrid plant.(iii) State the Mendel's law of Independent Assortment.(iv) Mention the phenotypes of the offspring's obtained in F2 generation.(v) What is the phenotypic ratio obtained in F2 generation?

Accepted Answer

(i) Genotype of F1 generation — Heterozygous Tall with Red flowers (TtRr)Phenotype — All heterozygous tall and red.(ii) Below are the possible combinations of the gametes that can be obtained:TR — Tall and RedtR — Dwarf and RedTr — Tall and Whitetr — Dwarf and White(iii) Mendel's law of Independent Assortment states that when there are two pairs of characters, the distribution of the alleles of one character into the gametes is independent of the distribution of the alleles of the other character (as seen in the production of gametes of the F1 hybrid in dihybrid cross).(iv) Tall red, Dwarf red, tall white, dwarf white.(v) 9:3:3:1

Question 12

Question 7(b)Briefly explain the following terms : [5](i) Reflex action(ii) Power of accommodation(iii) Photophosphorylation(iv) Hormone(v) Synapse

Accepted Answer

(i) A reflex action is an automatic/quick/immediate involuntary action in the body brought about by a stimulus.(ii) Power of accommodation is the ability of the eye lens to focus near and far objects clearly on the retina by adjusting its focal length.(iii) Photophosphorylation is the formation of energy rich compound Adenosine Triphosphate (ATP) from Adenosine Diphosphate (ADP) and inorganic Phosphate in the presence of light.(iv) Hormone is a secretion from some glandular part of the body, which is poured directly into blood and which acts on the target organs or cells of the same individual, bringing about coordination between distant parts of the body.(v) Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap.

Solved 2016 Question Paper ICSE Class 10 Biology

Section I 40 Marks

Section Ii 40 Marks