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Biology — Model Question Paper 1

Biology · Kerala SSLC (Class 10) · English Medium · SSLC 2027 pattern · English Medium · 40 marks · 90 min + 15 min cool-off

Section A

Questions 1–4 carry 1 score each. Answer all.

  1. One strand of a DNA segment has the base sequence T A C G G A. Which is the base sequence of the complementary strand? [1 mark]
    • A T G C C T
    • A U G C C U
    • T A C G G A
    • U T G C C T
  2. Light passes through the following parts of the eye before an image forms on the retina: (i) Lens (ii) Cornea (iii) Vitreous humour (iv) Pupil Choose the correct sequence. [1 mark]
    • (i), (ii), (iv), (iii)
    • (ii), (i), (iv), (iii)
    • (ii), (iv), (i), (iii)
    • (iv), (ii), (i), (iii)
  3. A gardener wants stem cuttings of a hibiscus plant to form roots quickly. Which of the following should be used? [1 mark]
    • Synthetic ethylene
    • Synthetic gibberellin
    • Abscisic acid
    • Synthetic auxin
  4. Which of the following is NOT a primary level (first line) immune mechanism? [1 mark]
    • Lysozyme in tears
    • Inflammatory response at a wound
    • Hydrochloric acid in the stomach
    • Wax in the ear

Section B

Questions 5–11 carry 2 scores each. Questions 7 and 10 have a choice — answer (A) or (B).

  1. Read the news report. "Patients with a serious intestinal infection caused by drug-resistant Clostridium difficile bacteria were not cured by antibiotics. They recovered after taking capsules containing beneficial bacteria collected from the faeces of healthy people." [2 marks]
    • (a) What is meant by the human microbiome?
    • (b) Write any two services the microbiome provides to our body.
  2. Two explanations are given for how cheetahs became fast runners. Explanation 1: Early cheetahs ran hard to catch prey. Constant use made their leg muscles stronger, and this acquired speed was passed on to their offspring. Explanation 2: Early cheetahs differed in speed. The faster ones caught more prey, survived and produced more offspring. Over many generations, fast runners became common. [2 marks]
    • (a) Name the theory behind each explanation.
    • (b) Which explanation is not accepted by modern science? Why?
  3. (A) Anu is reading a book. She then looks up at a distant hill and sees it clearly. [2 marks]
    • (a) What changes happen to the ciliary muscles and the lens when she looks at the distant hill?
    • (b) What is this ability of the eye called? Define it.

    OR

    (B) When a piece of sugar is placed on a tongue that has been wiped completely dry, the sweet taste is hardly felt.

  4. Observe the symptoms of two persons. Person X: weight loss, faster heartbeat, excessive sweating, anxiety Person Y: weight gain, slow heart rate, tiredness, cannot tolerate cold [2 marks]
    • (a) Identify the conditions of X and Y.
    • (b) Name the hormone involved and the cells that produce it.
  5. A patient with blood group A positive needs a blood transfusion. Three donors are available: • P — B positive • Q — O positive • R — AB positive [2 marks]
    • (a) Which donor's blood is suitable for the patient?
    • (b) Why is the blood of P and R not suitable?
  6. (A) The illustration shows the DNA fingerprint of a blood sample collected from a crime scene and those of three suspects. [2 marks]
    • (a) Which suspect's DNA matches the sample? Give the reason.
    • (b) On what basis does DNA fingerprinting identify individuals?

    OR

    (B) A global scientific project began in 1990 and was completed in 2003. It used gene mapping to find out the complete information in human DNA.

  7. After a head injury in an accident, a person shows these problems: (i) cannot keep balance while walking (ii) has difficulty in regulating body temperature and feels abnormal thirst [2 marks]
    • (a) Which part of the brain is likely to be damaged in (i)? Write its function.
    • (b) Which part of the brain is likely to be damaged in (ii)? Write its function.

Section C

Questions 12–17 carry 3 scores each. Questions 13 and 16 have a choice — answer (A) or (B).

  1. In pea plants, purple flower colour (P) is dominant over white flower colour (p). A heterozygous purple-flowered plant (Pp) is self-pollinated. [3 marks]
    • (a) Write the types of gametes produced by this plant.
    • (b) Show the possible genotypes of the offspring and give the genotypic ratio.
    • (c) Write the phenotypic ratio. Which trait was hidden in the parent and reappears in the offspring?
  2. (A) The genetic constitutions of three persons are given. P: 44 + XY Q: 44 + X0 R: 44 + XXY [3 marks]
    • (a) Which of them has the normal genetic constitution of a male? How many autosomes (somatic chromosomes) does this person have?
    • (b) Name the conditions of Q and R.
    • (c) Why is the chromosome from the father important in deciding whether a child is a boy or a girl?

    OR

    (B) During the first phase of meiosis, homologous chromosomes pair up. At the point where they touch, the chromatids break and exchange segments.

  3. A child accidentally touches a hot vessel and pulls the hand away at once. The path of the impulse is shown. Receptor in the skin → (A) → (B) in the spinal cord → (C) → Muscle [3 marks]
    • (a) Identify A, B and C.
    • (b) What is this pathway called? Why is the response so quick?
    • (c) Write one example of a reflex action controlled by the brain, and one way in which reflex actions help us.
  4. After playing football in the hot sun for two hours and sweating a lot, a student finds that he passes very little urine, and it is dark yellow. [3 marks]
    • (a) Name the hormone responsible for this. Where is it produced, and where is it stored and released?
    • (b) How does this hormone reduce the amount of urine?
    • (c) On a cold, rainy day, the same student drinks a lot of water. What will happen to the production of this hormone and to the amount of urine?
  5. (A) Observe the information about three diseases (disease — pathogen — mode of spread). • Malaria — (P) — female Anopheles mosquito • Filariasis — filarial worm — (Q) • Rat fever (Leptospirosis) — Leptospira — water contaminated with rat urine [3 marks]
    • (a) Identify P and Q.
    • (b) To which group of pathogens does Leptospira belong? Which type of medicine is used to treat rat fever?
    • (c) Suggest two measures to prevent diseases spread by mosquitoes.

    OR

    (B) HIV attacks a particular type of white blood cell and multiplies using its genetic mechanism.

  6. Observe the list of genetically modified organisms (GMOs). • Bt cotton • Golden rice • Pseudomonas putida • E. coli that produces human insulin [3 marks]
    • (a) What are genetically modified organisms?
    • (b) Write the special feature of Bt cotton and of Pseudomonas putida.
    • (c) Name the enzymes known as 'genetic scissors' and 'genetic glue' in recombinant DNA technology.

Section D

Question 18 carries 4 scores. Answer (A) or (B).

  1. (A) Observe the diagram of the human eye. [4 marks]
    • (a) Identify the parts labelled A and C.
    • (b) Which labelled part has no photoreceptor cells? Name it and say why.
    • (c) Name the fluid in the chamber between A and C. Write any one function of it.
    • (d) Name the disease caused when this fluid is not reabsorbed properly. How does it affect vision?

    OR

    (B) Observe the diagram of a neuron.

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