BIOLOGY (SCIENCE PAPER – 3)

Maximum Marks: 80
Time allowed: Two hours

Instructions:

• Answers to this Paper must be written on the paper provided separately.
• You will not be allowed to write during first 15 minutes. This time is to be spent in reading the question paper.
• The time given at the head of this Paper is the time allowed for writing the answers.
• Section A is compulsory. Attempt any four questions from Section B.
• The intended marks for questions or parts of questions are given in brackets [ ].

SECTION A (40 Marks)

(Attempt all questions from this Section.)

Question 1

Select the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only). [15]

(i) The sex chromosome in a human ovum is:

• (a) X chromosome
• (b) Y chromosome
• (c) Both X and Y chromosomes
• (d) Either X or Y chromosome

(ii) Which one of the following is a biodegradable waste?

• (a) Metal cans
• (b) E-waste
• (c) Plastic
• (d) Flowers

(iii) The heart sound 'Dup' is produced when:

• (a) Semilunar valves open
• (b) Atrio ventricular valves close
• (c) Semilunar valves close
• (d) Atrio ventricular valves open

(iv) Deplasmolysis occurs when a plasmolysed cell is placed in:

• (a) Concentrated salt solution
• (b) Tap water
• (c) Concentrated sugar solution
• (d) Hypertonic salt solution

(v) Alpha cells of Pancreas secrete:

• (a) Glycogen
• (b) Glucose
• (c) Glucagon
• (d) Insulin

(vi) Haploid number of chromosomes are found in:

• (a) Nephrons
• (b) Neurons
• (c) Skin cells
• (d) Sperms

(vii) The life span of an RBC is:

• (a) 120 days
• (b) 220 days
• (c) 20 days
• (d) 2 weeks

(viii) The statistical study of human population is called:

• (a) Mortality
• (b) Demography
• (c) Natality
• (d) Equality

(ix) The pale yellow colour of normal human urine is due to the pigment:

• (a) Melanin
• (b) Anthocyanin
• (c) Urochrome
• (d) Haemoglobin

(x) Stimulation of the nerves of the sympathetic nervous system:

• (a) Accelerates heartbeat
• (b) Constricts pupil of eyes
• (c) Increases peristalsis
• (d) Retards heartbeat

(xi) The site of light reaction in the cells of a green leaf is:

• (a) Nucleus
• (b) Grana of chloroplast
• (c) Cytoplasm
• (d) Stroma of chloroplast

(xii) The paper used to demonstrate unequal transpiration in a dicot leaf is:

• (a) Filter paper
• (b) Litmus paper
• (c) Starch paper
• (d) Cobalt chloride paper

(xiii) Vitreous humour is present between:

• (a) Cornea and Iris
• (b) Lens and Retina
• (c) Iris and Lens
• (d) Cornea and Lens

(xiv) Oxygenated blood to liver is supplied by:

• (a) Hepatic artery
• (b) Hepatic vein
• (c) Inferior venacava
• (d) Hepatic portal vein

(xv) During the synthesis phase of the cell cycle, more of:

• (a) RNA is synthesised
• (b) RNA and proteins are synthesised
• (c) DNA is synthesised
• (d) Glucose is synthesized

Question 2

(i) Name the following: [5]

• (a) The organelle that forms the aster during cell division.
• (b) A genetic disorder in which the blood does not clot.
• (c) The permanent stoppage of menstruation in human females around the age of 45 years.
• (d) The openings on the barks of trees through which transpiration occurs.
• (e) A gaseous plant hormone which promotes ripening of fruits.

(ii) Arrange and rewrite the terms in each group in correct order to be in a logical sequence beginning with the term that is underlined: [5]

• (a) Snake, Rabbit, Cabbage, Hawk.
• (b) Xylem, Soil water, Cortical cells, Root hair.
• (c) Receptor, Response, Effector, Spinal Cord
• (d) Fovea, Lens, Cornea, Conjunctiva.
• (e) Testis, Urethra, Sperm duct, Epididymis.

(iii) Match the items given in Column I with most appropriate ones in Column II and rewrite the correct matching pairs: [5]

(iv) Choose the odd one out from the following terms and name the category to which the others belong: [5]

• (a) Used bandages, Pesticides, Face masks, Syringes.
• (b) Dust, Smoke, Carbon monoxide, Effluents
• (c) Uterus, Urethra, Urinary bladder, Ureter
• (d) Menstrual phase, Telophase, Follicular phase, Luteal phase
• (e) Malleus, Incus, Cochlea, Stapes

(v) State the exact location of the following structures: [5]

• (a) Thyroid gland
• (b) Dura mater
• (c) Amniotic fluid
• (d) Papillary muscles
• (e) Islets of Langerhans

SECTION B (40 Marks)

(Attempt any four questions from this Section.)

Question 3

(i) Write the overall chemical equation for photosynthesis. [1]

(ii) Mention any two functions of blood. [2]

(iii) Differentiate between Karyokinesis and Cytokinesis. [2]

(iv) Excessive use of fertilizers in agricultural fields reduces the yield of crops. Justify the statement. [2]

(v) Study the diagram given below and answer the questions that follow: [3]

• (a) Name the phenomenon depicted by the shoot in the above diagram.
• (b) Which plant hormone plays an important role in the above movement?
• (c) Complete and rewrite the given statement by filling in the correct terms: Shoots show positive _________ whereas, roots show positive __________.

Question 4

(i) Expand the abbreviation – DNA. [1]

(ii) What is Active transport? [2]

(iii) Mention the two pairs of nitrogenous bases which pair with each other with hydrogen bonds. [2]

(iv) State Mendel's 'Law of Segregation'. [2]

(v) Draw a neat, labelled diagram of a human sperm. [3]

Question 5

(i) Explain the term 'Population density'. [1]

(ii) Name the two surgical methods of population control. [2]

(iii) Mention two factors responsible for population explosion in India. [2]

(iv) Name any two resources which come under pressure due to rising population. [2]

(v) The diagram given below depicts the climate change on planet Earth. Answer the following questions: [3]

• (a) Name the climatic phenomenon for the increase in Earth's temperature.
• (b) Mention one reason for this warming.
• (c) What measure can be taken to prevent this climate change?

Question 6

(i) Define the term Transpiration. [1]

(ii) State any two adaptations in plants to reduce transpiration. [2]

(iii) Mention any two functions of the human foetal placenta. [2]

(iv) What is the significance of the human testes being located in scrotal sacs outside the abdomen? [2]

(v) Draw a neat, labelled diagram of a Malpighian Capsule. [3]

Question 7

(i) What is a Reflex action? [1]

(ii) Renal cortex has a dotted appearance and Renal medulla has a striped appearance. Explain. [2]

(iii) What are the two functions of cerebellum. [2]

(iv) Distinguish between Semicircular canals and Utriculus based on their function. [2]

(v) A potted plant with variegated leaves was kept in dark for 24 hours and then placed in bright sunlight. Answer the following questions. [3]

• (a) Which aspect of photosynthesis is being tested in the above diagram?
• (b) Why was the plant kept in dark for 24 hours?
• (c) After the starch test what will be the colour of the yellow and green parts of the leaf? Give reasons to support your answer.

Question 8

(i) Define the term Mutation. [1]

(ii) A pure breeding red flower variety of pea plant (RR) is crossed with a pure breeding white flower variety of pea plant (rr). Draw a Punnett square to find out the Phenotypic and Genotypic ratios of the progeny belonging to the F₂ generation. [2]

(iii) Leaves of certain plants roll up on a hot sunny day. Explain by giving suitable reasons. [2]

(iv) What is a semi permeable membrane? Name the semi permeable membrane present in a plant cell. [2]

(v) The diagram below depicts the human heart in one of its phases. Answer the questions that follow: [3]

• (a) Which part of the heart is in the contraction phase?
• (b) Give a suitable reason to justify your answer in (a).
• (c) Distinguish between Systole and Diastole.