StudyWithSmile — free flashcards, quizzes and exam practice for school students

Biology — Model Question Paper 2

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. Arrange the following members of the human evolutionary path from the earliest to the most recent. (i) Homo erectus (ii) Sahelanthropus tchadensis (iii) Homo habilis (iv) Australopithecus [1 mark]
    • (iv), (ii), (iii), (i)
    • (ii), (iv), (iii), (i)
    • (ii), (iii), (iv), (i)
    • (i), (iii), (iv), (ii)
  2. In a chromosome, DNA strands wind around a group of eight histone proteins. What is the structure formed called? [1 mark]
    • Chromatid
    • Centromere
    • Nucleotide
    • Nucleosome
  3. Choose the option in which both the statement and the reason are correct, and the reason explains the statement. [1 mark]
    • Statement: Fever is an immune mechanism. Reason: A higher body temperature helps phagocytes destroy pathogens faster and slows the growth of pathogens.
    • Statement: Antibiotics are used to treat viral fever. Reason: Antibiotics destroy viruses.
    • Statement: B lymphocytes produce antibodies. Reason: B lymphocytes mature in the thymus gland.
    • Statement: Basophils help blood to clot. Reason: Basophils produce heparin.
  4. Which branch of science analyses large amounts of biological data by combining computer science, mathematics and statistics? [1 mark]
    • Bioremediation
    • Cryopreservation
    • Bioinformatics
    • Gene mapping

Section B

Questions 5–11 carry 2 scores each. Questions 6 and 9 have a choice — answer (A) or (B).

  1. A normal human body cell has 23 pairs of chromosomes. A man's body cells have the genetic constitution 44 + XY. [2 marks]
    • (a) Write the chromosome constitution of the two types of sperm he produces.
    • (b) Which gene on the Y chromosome decides the development of a male? What is its role?
  2. (A) A bacterial infection that was once easily cured by an antibiotic no longer responds to that antibiotic. [2 marks]
    • (a) How did the bacteria become resistant to the antibiotic?
    • (b) What are superbugs? Why are they a major concern in healthcare?

    OR

    (B) In the brain and spinal cord, some regions look white and some look grey.

  3. Observe the nervous systems of different organisms. • Hydra — a neural network with no control centre • Planaria — a pair of nerve ganglia in the head region • Insects — a brain in the head and a pair of ganglia in each segment [2 marks]
    • (a) What trend in the evolution of the nervous system does this show?
    • (b) Which part of the human cerebrum is more developed than in other mammals? What happens in this part when we learn new things?
  4. A gardener makes two observations. (i) A potted seedling kept near a window bends and grows towards the light. (ii) Grape farmers spray a hormone to increase the size of the fruits. [2 marks]
    • (a) Explain how auxin causes the bending in (i).
    • (b) Name the hormone used in (ii). Write one other use of it in agriculture.
  5. (A) Information from a Primary Health Centre poster: • MMR vaccine — contains neutralised pathogens • HPV vaccine — contains parts of pathogens • COVID-19 vaccine — contains parts of the genetic material of the pathogen [2 marks]
    • (a) How does a vaccine give protection against a disease?
    • (b) Why is vaccination necessary for deadly diseases like tetanus and diphtheria?

    OR

    (B) Acquired immunity is carried out mainly by two types of lymphocytes.

  6. The steps in the stem cell therapy for sickle cell anaemia are given in jumbled order. (i) The stem cells containing the gene are injected into the patient. (ii) Stem cells that produce blood cells are collected from the patient. (iii) The active gene is incorporated into the stem cells using viruses as vectors. [2 marks]
    • (a) Arrange the steps in the correct order.
    • (b) This is somatic gene therapy. How does it differ from germline gene therapy?
  7. A student walking home sees a snake on the path. Her heart starts racing and she runs away quickly. [2 marks]
    • (a) Which part of the adrenal gland responds in this situation? Name the hormones it secretes.
    • (b) Write any two changes these hormones bring about in the body.

Section C

Questions 12–17 carry 3 scores each. Questions 12 and 15 have a choice — answer (A) or (B).

  1. (A) In pea plants, yellow seed colour (Y) is dominant over green (y), and round seed shape (R) is dominant over wrinkled (r). F1 plants with genotype YyRr, obtained from a cross between pure yellow-round (YYRR) and pure green-wrinkled (yyrr) plants, are self-pollinated. [3 marks]
    • (a) Write the types of gametes produced by the F1 plants.
    • (b) Write the phenotypes in F2 and their ratio.
    • (c) Which F2 phenotypes were not seen in the original parents? Which inference of Mendel explains their appearance?

    OR

    (B) Observe the comparison of DNA and RNA (feature — DNA — RNA). • Number of strands — two — (P) • Sugar — deoxyribose — (Q) • Nitrogen bases — A, G, C, T — A, G, C, (R)

  2. Observe the diagram of a cross-section of the spinal cord. [3 marks]
    • (a) Identify A and B.
    • (b) Write the function of A and B.
    • (c) Identify C and D. In which of these are the cell bodies of neurons abundant?
  3. The flow chart shows how we sense smell. Odour particles enter the nasal cavity → dissolve in (P) → (Q) are stimulated and form impulses → (R) → Brain [3 marks]
    • (a) Identify P and Q.
    • (b) Identify R. What happens when impulses reach the brain?
    • (c) Food seems tasteless to a person whose nose is blocked by a cold. Give the reason.
  4. (A) The normal level of calcium in blood is 9–11 mg/dL. It is kept at this level by two hormones. [3 marks]
    • (a) Which hormone acts when the blood calcium level falls? Which gland produces it?
    • (b) Write any two actions of this hormone that raise the calcium level.
    • (c) Name the hormone that lowers the calcium level and the cells that produce it.

    OR

    (B) Three conditions are described. X: An adult's palms, feet and jaw grow excessively. Y: A child shows stunted growth. Z: A child grows excessively tall.

  5. A thorn pricks Rahul's finger. Soon the area becomes red, warm and swollen. [3 marks]
    • (a) Name the chemical released by the cells at the injured part. What is its effect on blood vessels?
    • (b) Name two white blood cells that reach the area and engulf the pathogens. What is this process called?
    • (c) How is the engulfed pathogen destroyed inside the phagocyte?
  6. Human insulin is now produced on a large scale using the bacterium E. coli. A plasmid is cut, the human insulin gene is joined to it, and the plasmid is put back into the bacterium. [3 marks]
    • (a) Name the enzymes used to cut the gene and to join it to the plasmid.
    • (b) What is the role of the plasmid in this technology? Name one other type of vector.
    • (c) What is the E. coli that carries the human gene called? Write one concern about releasing such organisms into nature.

Section D

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

  1. (A) Observe the diagram of the human ear. [4 marks]
    • (a) Identify the parts labelled C and E.
    • (b) D is a chain of three small bones. Name them in order, starting from C.
    • (c) Identify G and write any one function of it.
    • (d) Where are the auditory receptors present in E? How do they produce the sense of hearing?

    OR

    (B) Observe the diagram of a synapse.

Sign in free to see model answers and marking points, and check your score.

All Biology chapters and papers