ICSE Class 10 Biology 2020 Question Paper
Biology is Science Paper-3. The duration of the paper is two hours. Attempt all questions from Section I and any four questions from Section II.
Section I (40 Marks)
(a) Name the following: 
- The process of transformation of several glucose molecules into one molecule of starch.
- The point of attachment of two chromatids.
- The iron containing pigment in erythrocytes.
- The duct which transports urine from the kidney to the urinary bladder.
- The part of the brain which is concerned with memory.
(b) Explain the following terms: 
- Population density
(c) Given below are certain groups of terms. In each group the first pair indicates a relationship between the two terms. Rewrite and complete the second pair on a similar basis. 
Example: Cytoplasm : Cytokinesis :: Nucleus : Karyokinesis.
- Widening of hips: Oestrogen :: Deepening of voice in males : _______.
- Brain : Meninges :: Heart : _______.
- Insulin : Beta-cells :: Glucagon : _________.
- Kidney: Renal artery :: Liver : _________.
- Uterus : Implantation :: Fallopian tube : ______.
(d) Given below are sets of five terms each. Rewrite the terms in correct order in a logical sequence beginning with the first word that is underlined: 
- Stimulus, Response, Receptor, Effector, Spinal cord.
- Root hair, Endodermis, Epidermis, Xylem, Cortex.
- Conjunctiva, Yellow spot, Pupil, Vitreous Humour, Aqueous Humour.
- Australopithecus, Cro-Magnon Man, Homo erectus, Neanderthal Man, Homo sapiens.
- Artery, Capillaries, Venule, Vein, Arteriole.
(e) Choose the correct answer from the four options given below: 
(i) The fusion of the sperm and ovum is termed as:
(ii) Agranulocytes are:
- Lymphocytes, Monocytes
- Lymphocytes, Basophils
- Eosinophils, Basophils
- Eosinophils, Monocytes
(iii) Which of the following is not a natural reflex action?
- Blinking of eyes due to strong light
- Salivation at the sight of food
- Sneezing when any irritant enters the nose
(iv) The structural and functional units of excretion in the human kidney is the:
- Bowman’s capsule
- Renal pelvis
(v) In a human female, ovum consists of:
- 23 pairs of autosomes
- 22 pairs of autosomes and 1 pair of sex chromosomes
- 22 autosomes and 1 Y-chromosome
- 22 autosomes and 1 X-chromosome
(f) Identify the ODD term in each set and name the CATEGORY to which the remaining three belong: 
- Auxin, Ethylene, Adrenaline, Cytokinin
- Tympanum, Ear ossicles, Auditory canal, Pinna
- Syringes, Soiled dressings, Discarded needles, Household detergents
- Exophthalmic Goiter, Simple Goitre, Cretinism, Myxoedema
- Adenine, Guanine, Creatinine, Cytosine
(g) Match the items given in column A with the most appropriate ones in Column B and REWRITE the correct matching pairs: 
- Biston betularia
- Clotting of blood
- balance of the body
- Light independent reaction
- diffusion of gases
- Peppered moth
- Light dependent reaction
(h) The diagram given below represents a plant movement. 
Answer the following questions:
- Name the tropic movement shown in the diagram.
- Explain the tropic movement mentioned in (i).
- Label the part marked 'A'.
- What is part A attracted to?
- Give an example of a plant which shows Thigmotropism.
Section II (40 Marks)
(a) The diagram given below represents an experiment to prove the importance of a factor in photosynthesis. Answer the questions that follow: 
- Which factor is being studied here?
- What is the purpose of keeping KOH in the flask?
- Explain the term Photosynthesis.
- What will you observe when the leaf A is tested for starch?
- Write a well balanced chemical equation for the process of photosynthesis.
(b) The diagram given below represents the simplified pathway of the circulation of blood. Answer the questions that follow: 
- Name the blood vessels labelled 1 to 4.
- Which blood vessel supplies oxygenated blood to the muscles of the heart?
- What is the importance of blood vessel labelled 5?
- What is the type of blood circulation that takes place between the heart and the lungs?
- Draw a diagram of the different blood cells as seen in a smear of human blood.
(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:
- Name the defect that has been corrected. Which type of lens has been used for the correction?
- Mention one cause for the above defect.
- Where would the image have formed if the above lens was not used for correction?
- Name the three concentric layers of the eyeball.
- Draw a neat, labelled diagram of a neuron.
(b) Give the biological reasons for the following statements: 
- It is advisable to keep green plants in an aquarium.
- Water pollution is a major cause of concern in our country.
- We cannot distinguish colours in dim light.
- Medical discoveries such as antibiotics and vaccinations have indirectly contributed to the sharp rise in human population.
- Homo sapiens sapiens is the most highly evolved form of man.
(a) The figure given below shows a part of a nephron. Answer the questions that follow: 
- In which region of the kidney is the above structure present?
- Label the parts numbered 1 to 4.
- What is the technical term for the process that occurs in part 3?
- Why is fluid X not called urine? Justify your answer.
- Draw a neat, labelled diagram of the urinary system of man.
(b) Differentiate between the following pairs on the basis of what is mentioned in the brackets: 
- Transpiration and Guttation (place of occurrence)
- Biodegradable waste and Non-biodegradable waste (One example)
- Population control and Swachh Bharat Abhiyan (One objective)
- Osmosis and Active Transport (Substances undergoing movement)
- Metaphase and Anaphase (Position of chromosomes)
(a) The diagram below represents an experiment to demonstrate a certain phenomenon in a green plant: 
- Will the level of mercury in the glass tubing rise or fall? Which conducting tissue of the plant does the glass-tubing represent?
- Define Transpiration.
- How will the rate of the above process differ if the environment of the plant has: 1. Less humidity 2. High temperature?
- State any two advantages of transpiration to the plant.
- Draw a neat labelled diagram of a Plasmolysed cell.
(b) Give appropriate biological/ technical terms for the following: 
- The sensory organ in Cochlea.
- Number of live births per 1000 people per year.
- The point of contact between two neurons.
- The accessory gland in human males whose secretion neutralises the acid in the vagina.
- Condition when blood sugar level is lowered in the blood.
- Structure which helps in the adjustment of the size of the pupil.
- A surgical method of fertility control in human males.
- Process by which leucocytes migrate through the walls of capillaries.
- A sudden inheritable change in one or more genes.
- A non-dividing phase of the cell cycle where more DNA is synthesised.
(a) State two functions of: 
(b) Complete the table: 
(a) A homozygous dominant tall pea plant bearing red flowers (TTRR) is crossed with a homozygous recessive dwarf pea plant bearing white flowers (ttrr). 
- What is the phenotype and genotype of F1 individuals?
- Write the possible combination of gametes that are obtained when two F1 hybrid plants are crossed.
- Mention the phenotypic ratio of the F2 generation.
- State Mendel’s Law of Independent Assortment.
- Name two X-linked disorders found in humans.
(b) The diagram given below is that of a developing human foetus. Answer the questions that follow: 
- Label the parts numbered 1 to 3 in the diagram.
- Mention any two functions of the part labelled 2 in the diagram.
- Explain the significance of the part numbered 3 in the diagram.
- Define the term ‘Gestation’. What is the normal gestational period of the developing embryo?
- Mention the sex chromosomes in a male and female embryo.