CIE iGCSE Co-Ordinated Science B1.1 Characteristics of living organisms Exam Style Questions Paper 4
Question
(a) Sensitivity is one of the characteristics of living organisms. Define the term sensitivity.
▶️Answer/Explanation
Answer: Sensitivity is the ability to detect and respond to changes in the environment.
Detailed Solution: Sensitivity refers to the ability of living organisms to detect changes in their environment (stimuli) and respond to them appropriately. This is essential for survival, as it allows organisms to adapt to their surroundings.
(b) (i) Draw an X on Fig. 1.1 to identify the position of the blind spot.
▶️Answer/Explanation
Answer: X drawn on blind spot
Detailed Solution: The blind spot is the area on the retina where the optic nerve exits the eye. It lacks photoreceptor cells, so it cannot detect light. The X should be placed at the position where the optic nerve connects to the retina.
(ii) Identify the letter from Fig. 1.1 that shows the part that:
contains receptor cells ……
controls the amount of light entering the eye ……
refracts light. ……
▶️Answer/Explanation
Answer: H (contains receptor cells); B (controls the amount of light entering the eye); C (refracts light)
Detailed Solution: – H represents the retina, which contains photoreceptor cells (rods and cones) that detect light. – B represents the iris, which controls the amount of light entering the eye by adjusting the size of the pupil. – C represents the lens, which refracts light to focus it onto the retina.
(iii) A person changes their focus from a near object to a distant object. Describe the changes that occur to the parts labelled A, E, and F in Fig. 1.1 when focusing on a distant object.
▶️Answer/Explanation
Answer: A becomes thinner; E tightens/stretches; F relaxes
Detailed Solution: – A (lens) becomes thinner to reduce its refractive power, allowing light from distant objects to focus on the retina. – E (ciliary muscles) tighten or stretch to flatten the lens. – F (suspensory ligaments) relax, reducing tension on the lens.
(c) The eye forms part of the peripheral nervous system. Name the two parts of the central nervous system.
▶️Answer/Explanation
Answer: brain; spinal cord
Detailed Solution: The central nervous system (CNS) consists of the brain and the spinal cord. The CNS processes information received from the peripheral nervous system (PNS), which includes nerves outside the brain and spinal cord.