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CIE iGCSE Co-Ordinated Science B13.2 Hormones 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

(a) A student watches some scary movies.
The average pulse rate of the student is measured during each movie.
The highest pulse rate of the student is also recorded.
Table 1.1 shows the results.
The student has a ‘flight or fight’ response to the movies causing adrenaline to be released.
(i) Identify the movie in Table 1.1 that results in the lowest average pulse rate.
(ii) Identify the movie in Table 1.1 that results in the greatest release of adrenaline.
(iii) Movie D lasts 2 hours. Using the average pulse rate, calculate the total number of heart beats during the movie.
(iv) Circle the target organ for adrenaline that causes the results in Table 1.1.
heart       kidney       ovary       stomach       skin
(b) State two other effects of adrenaline on the body.
Do not include the effect on pulse rate.
(c) State the component of blood that transports the hormone adrenaline.
(d) The ‘flight or fight’ situation is a response to a change in the environment.
This is an example of one of the characteristics of living things.
(i) State the name of this characteristic.
(ii) State the name of one other characteristic of living things.

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

• Topic B13.2 — Hormones (Parts (a), (b), (c))
• Topic B1.1 — Characteristics of living organisms (Part (d))

▶️ Answer/Explanation

(a)(i) B

Movie B has the lowest average pulse rate of 79 beats per minute, which is the smallest value in the table.
Comparing all five movies: A = 82, B = 79, C = 84, D = 80, E = 86 beats per minute.
Therefore, movie B gives the lowest average pulse rate.

(a)(ii) C

Greater adrenaline release causes a greater increase in pulse rate, reflected by the largest difference between highest and average pulse rate.
The difference in pulse rate values are: A = 40, B = 37, C = 48, D = 43, E = 18.
Movie C has the largest difference (48 beats per minute), indicating the greatest release of adrenaline.

(a)(iii) 9600 beats

Convert 2 hours to minutes: \(2 \times 60 = 120\) minutes.
Total beats = average pulse rate \(\times\) time = \(80 \times 120 = 9600\) beats.
The average pulse rate for movie D is 80 beats per minute.

(a)(iv) heart

Adrenaline acts on the heart to increase heart rate, which is the effect being measured in the table.
The heart is the target organ of adrenaline responsible for the changes in pulse rate observed.
Other organs listed (kidney, ovary, stomach, skin) do not cause the pulse rate change shown.

(b) Any two from: increased breathing rate; widening of pupils; increased blood flow to muscles.

Adrenaline prepares the body for a ‘fight or flight’ response by increasing breathing rate to supply more oxygen.
It also causes widening (dilation) of the pupils to improve vision in a threatening situation.
Additional effects include increased blood glucose levels and redirection of blood flow to muscles.

(c) plasma

Hormones are chemical messengers transported dissolved in the blood plasma.
Plasma is the liquid component of blood and carries hormones, nutrients, and waste products around the body.
Adrenaline travels from the adrenal glands via the plasma to its target organ, the heart.

(d)(i) sensitivity

Sensitivity is the ability of a living organism to detect and respond to changes in its internal or external environment (stimuli).
The ‘flight or fight’ response is triggered by a stimulus (scary movie) detected by the nervous system.
This response demonstrates that the student can sense and react to environmental changes.

(d)(ii) Any one from: movement; respiration; growth; reproduction; excretion; nutrition.

All living organisms share seven characteristics, often remembered by the acronym MRSGREN.
These include movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition.
Any one of these (other than sensitivity) is an acceptable answer.

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