Question
The diagram shows the structure of human skin.
What are X, Y and Z?
Answer/Explanation
Answer: C
Let’s identify each part in the diagram:
X:
- X is pointing to a coiled tubular structure in the lower dermis/hypodermis area.
- This matches the appearance and location of a sweat gland.
- X = Sweat gland
Y:
- Y is connected to the side of the hair follicle and extends diagonally upward.
- This is a muscle — it pulls the hair upright during goosebumps.
- Y = Hair erector muscle
Z:
- Z is a long, thin structure connecting to the base of a receptor and running through the skin.
- This looks like a nerve fiber, specifically a sensory neurone.
- Z = Sensory neurone
Correct Matching:
| Label | Structure |
|---|---|
| X | Sweat gland |
| Y | Hair erector muscle |
| Z | Sensory neurone |
Question
The diagram refers to questions 2 and 3. It shows a heterotrophic, unicellular, freshwater organism that has been placed in distilled water. The short arrows show movement of water and the long arrows show a sequence of steps.
What life function is illustrated?
A. Nutrition
B. Homeostasis
C. Endocytosis
D. Response
▶️Answer/Explanation
Answer: B. Homeostasis
Explanation:
The diagram shows a unicellular freshwater organism (like an amoeba or paramecium) placed in distilled water, which is hypotonic (has a lower solute concentration than the inside of the cell). In such conditions:
- Water enters the cell by osmosis, as illustrated by the short arrows pointing inward.
- This can cause the cell to swell due to the influx of water.
- To prevent bursting, the cell uses a contractile vacuole (marked “X”) to expel the excess water.
- The vacuole fills with water and periodically contracts to pump it out — helping maintain a stable internal environment.
This process is a classic example of homeostasis, which is the regulation of internal conditions to maintain life.
Why not the other options?
A. Nutrition: Not about food intake or digestion here.
C. Endocytosis: No indication of engulfing food or other particles.
D. Response: While the organism is reacting to its environment, the key process is maintaining internal balance, which defines homeostasis.
Question
The graph shows human body temperature variation in a daily rhythm of 24 hours.
Which hormone controls this variation?
A. Progesterone
B. Insulin
C. Glucagon
D. Thyroxin
▶️Answer/Explanation
Answer: D. Thyroxin
Explanation:
The graph shows the circadian rhythm of human body temperature, which follows a roughly 24-hour cycle. This rhythm is part of the body’s internal biological clock.
- Thyroxin, a hormone produced by the thyroid gland, plays a crucial role in regulating the body’s basal metabolic rate (BMR), which affects body temperature.
- It influences metabolic processes that produce heat, thus impacting the daily fluctuations in body temperature.
Let’s briefly review the other options:
A. Progesterone: Affects body temperature in females during the menstrual cycle, but it does not regulate the daily rhythm of body temperature.
B. Insulin: Regulates blood glucose levels, not body temperature.
C. Glucagon: Also affects blood sugar levels, not body temperature.
Question
How would the body respond to a rise above normal body temperature?
▶️Answer/Explanation
Answer: C
Explanation:
To respond to a rise above normal body temperature, the body activates mechanisms to cool down and return to homeostasis. These mechanisms are part of negative feedback systems, which counteract the change.
From the table, the correct responses to a rise in body temperature are:
- Increased secretion from sweat glands (sweating cools the body via evaporation)
- Vasodilation of skin blood vessels (increases heat loss through the skin)
These are both negative feedback responses, as they work to reduce the elevated body temperature back to normal.
So, the correct type and responses are:
- C. negative – vasodilation of skin blood vessels
- (And also part of A, but it should be classified as negative, not positive)
Thus, C is the correct match from the table.
Question
What conveys messages from the central nervous system to an endocrine gland?
A. Sensory neurons
B. Hormones
C. Interneurons
D. Motor neurons
▶️Answer/Explanation
Answer: D. Motor neurons
Explanation:
- The central nervous system (CNS) processes information and sends out commands to effectors.
- Motor neurons transmit electrical impulses from the CNS to muscles or glands (including endocrine glands).
- These impulses cause the endocrine glands to release hormones or respond accordingly.
- Sensory neurons carry information to the CNS from sensory receptors, not from CNS to glands.
- Interneurons connect neurons within the CNS and do not send messages to glands.
- Hormones are chemical messengers released by endocrine glands, not neurons that transmit messages from CNS