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CIE iGCSE Co-Ordinated Science B13.1 Coordination and response Exam Style Questions Paper 3

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Question

Humans are able to detect and respond to changes in their internal and external environment.
(a) The ability to detect and respond to changes in the environment is one of the characteristics of living organisms.
Circle this characteristic of living organisms.
excretion       growth       movement       nutrition       sensitivity
(b) Fig. 3.1 is a diagram of some of the organs involved in detecting and responding to changes in the environment.
(i) Identify the organs from Fig. 3.1 that are part of the central nervous system (CNS).
(ii) Identify the organ from Fig. 3.1 that secretes insulin.
(iii) Some of the organs shown in Fig. 3.1 conduct electrical impulses through specialised cells.
Name the specialised cells that conduct electrical impulses.
(iv) Some of the organs shown in Fig. 3.1 secrete hormones.
Complete the sentences about hormones.
Hormones are described as          substances.
They are produced by          and are carried by the          plasma.
(c) Adrenaline is a hormone.
Describe when adrenaline is secreted and the effects of adrenaline on the body.

Topic codes:

• Topic B13.1 — Coordination and response (Part (a) & (b)(iii))
• Topic B13.2 — Hormones (Part (b)(i), (b)(ii), (b)(iv) & (c))

▶️ Answer/Explanation

(a) Sensitivity
Sensitivity (also called responsiveness) is the ability of living organisms to detect and respond to changes in their internal or external environment. This is a key characteristic of life that enables organisms to survive and adapt to their surroundings.

(b)(i) Brain and spinal cord
The brain and spinal cord together form the central nervous system (CNS). The CNS coordinates and regulates body functions by processing information from sensory receptors and sending instructions to effectors.

(b)(ii) Pancreas
The pancreas secretes the hormone insulin, which regulates blood glucose concentration. Insulin is produced by the beta cells in the islets of Langerhans within the pancreas.

(b)(iii) Neurones (nerve cells)
Neurones are specialised cells that conduct electrical impulses rapidly throughout the nervous system. They transmit signals from sensory receptors to the CNS and from the CNS to effectors.

(b)(iv) chemical ; glands ; blood
Hormones are described as chemical substances (chemical messengers) produced by glands (endocrine glands). They are carried by the blood plasma to target organs where they have specific effects. Unlike nerve impulses, hormones travel more slowly but produce longer-lasting effects.

(c) Adrenaline is secreted during ‘fight or flight’ situations.
Adrenaline is secreted by the adrenal glands in response to stress, fear, or danger. This prepares the body for rapid action. The effects include:

  • Increased breathing rate — delivers more oxygen to muscles for increased respiration
  • Increased heart rate — pumps more blood to muscles and brain
  • Increased pupil diameter — allows more light to enter the eyes for better vision
  • Other effects include increased blood flow to muscles, increased blood glucose concentration, and diversion of blood away from the digestive system

Question

Fig. 4.1 shows part of a food web on a remote island.
(a) State the principal source of energy input to the food web in Fig. 4.1.
(b) Identify the two organisms in Fig. 4.1 that the lapwing bird eats.
(c) Identify all the producers in the food web in Fig. 4.1.
(d) Hedgehogs are introduced to the island by humans.
Use Fig. 4.1 to describe how hedgehogs affect the population of lapwing birds.
(e) When organisms in the food web die, other organisms like earthworms get their energy from the dead organic material.
State the type of organism that gets its energy from dead organic material.
(f) Hedgehogs hunt at night when it is dark.
Complete the sentences about how hedgehogs detect their prey.
Choose words from the list.
ciliated       chemicals       light       motor       receptor       sound
Hedgehogs use their sense of smell to detect …………………… in the air.
Their nose contains groups of …………………… cells which detect the smell.

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic B18.1 — Energy flow (Part (a))
• Topic B18.2 — Food chains and food webs (Part (b), (c), (d), (e))
• Topic B13.1 — Coordination and response (Part (f))

▶️ Answer/Explanation

(a) Sun
The Sun is the principal source of energy input to all food webs. Plants capture light energy from the Sun and convert it into chemical energy through photosynthesis.

(b) caterpillar and leaf beetle
The lapwing bird eats both caterpillars and leaf beetles, as shown by the arrows pointing from these organisms to the lapwing bird in the food web.

(c) Primrose plants and buttercup plants
Producers are organisms that make their own food by photosynthesis. In this food web, the primrose plants and buttercup plants are the producers at the base of the food web.

(d) Hedgehogs cause the population of lapwing birds to decrease.
Hedgehogs directly eat lapwing birds, reducing their numbers. Additionally, hedgehogs eat caterpillars, which are also a food source for lapwing birds. This increases competition for food, further reducing the lapwing population.

(e) Decomposer
Decomposers such as earthworms, bacteria and fungi obtain their energy from dead or waste organic material, breaking it down and releasing nutrients back into the ecosystem.

(f) Hedgehogs use their sense of smell to detect chemicals in the air.
Their nose contains groups of receptor cells which detect the smell.
Receptor cells are specialised cells that detect specific stimuli such as chemicals (for smell), light, or sound. In the nose, chemoreceptors detect chemical molecules in the air.

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