SSLC Examination 2025 - Biology Answer Key
Section 1: Answer any 5 questions from Q. No. 1 to 6 (1 score each)
1. Which is the main endocrine gland that controls metabolic activities?
(b) Thyroid gland
(The thyroid gland controls metabolic activities through thyroxine hormone)
2. Which of the following nucleotides is found only in RNA?
(b) U
(Uracil (U) is found only in RNA, while thymine (T) is found only in DNA)
3. "New species are formed by the inheritance of sudden changes that occur in genes". Which scientist proposed this explanation?
(d) Hugo de Vries
(Proposed the Mutation Theory of evolution)
4. Which of the following activity is correct while viewing nearby objects?
(c) (i) and (iv) are correct
(When viewing nearby objects: ciliary muscles contract and focal length decreases)
5. Correct the mistakes, if any in the underlined part of the given statements.
- (a) Correct as is (BCG does prevent Tuberculosis)
- (b) Incorrect - should be "Rh antigen" instead of "D antigen"
- (c) Incorrect - Thrombin is the enzyme that converts fibrinogen to fibrin
6. Some diseases and proteins produced through Genetic engineering for their treatment are given. Choose the correct pair.
(b) Interferons - Viral diseases
(Interferons are proteins used to treat viral infections)
Section 2: Answer any 6 questions from Q. No. 7 to 13 (2 scores each)
7. Analyse the given statements 'A' and 'B' and answer the following questions.
(a)
- A: Sickle cell anemia
- B: Hemophilia
8. Observe the given illustration and answer the questions.
(a) They have similar basic structure (homologous organs)
(b) Homologous organs suggest common ancestry and adaptive radiation in evolution
(b) Homologous organs suggest common ancestry and adaptive radiation in evolution
9. Observe the cross-section of a nerve and write answers to the questions.
(a) 'X' (likely myelin sheath) insulates the nerve fiber and speeds up impulse conduction
(b) Sensory nerves carry impulses from receptors to CNS, motor nerves carry impulses from CNS to effectors
(b) Sensory nerves carry impulses from receptors to CNS, motor nerves carry impulses from CNS to effectors
10. Analyse the newspaper report given below and answer the questions.
(a) Sharing contaminated needles transmits HIV through blood contact
(b) AIDS becomes fatal as HIV destroys T-cells, weakening immunity against opportunistic infections
(b) AIDS becomes fatal as HIV destroys T-cells, weakening immunity against opportunistic infections
11. Explain the role of each of the following activities in defense mechanism.
(a) Lysosomes release digestive enzymes to destroy pathogens during phagocytosis
(b) Pyrogens induce fever which inhibits pathogen growth and enhances immune response
(b) Pyrogens induce fever which inhibits pathogen growth and enhances immune response
12. Analyse each of the given situations and explain how variations are formed in the offspring.
(a) Chromosome pairing and crossing over during meiosis creates new gene combinations
(b) Random segregation of chromosomes during gamete formation creates genetic variation
(b) Random segregation of chromosomes during gamete formation creates genetic variation
13. The main parts and functions of brain are given in the box. Arrange them in the following table suitably.
| Part | Function |
|---|---|
| Thalamus | Acts as relay station of impulses |
| Cerebellum | Maintains equilibrium of the body |
| Hypothalamus | Maintains homeostasis |
| Cerebrum | Controls voluntary movements |
Section 3: Answer any 2 questions from Q. No. 21 to 23 (4 scores each)
21. Arrange columns B and C according to column A.
| A - Gland | B - Hormone | C - Function |
|---|---|---|
| Pituitary | Prolactin | Production of milk |
| Adrenal gland | Cortisol | Slows down the action of defense cells |
| Ovary | Progesterone | Implantation of embryo in the uterus |
| Hypothalamus | Releasing hormone | Controls the production of tropic hormones |
22. Redraw the diagram, identify and label the parts with their names.
(Diagram labeling would show):
- (a) Cornea/Pupil - allows light entry
- (b) Ciliary muscles - adjust lens curvature
- (c) Iris - adjusts pupil size based on light intensity
23. Answer the questions given below regarding diagnosis and treatment in Modern medicine.
(a)
- EEG: Records brain's electrical activity (diagnose epilepsy, brain disorders)
- ECG: Records heart's electrical activity (diagnose heart conditions)
- Uses: Treat bacterial infections by killing/inhibiting bacteria
- Side effects: May kill beneficial bacteria, can lead to antibiotic resistance with overuse