Revision 1
Define homeostasis
Homeostasis is the ability of an organism to maintain a stable internal environment (e.g., body temperature, blood glucose) despite external changes.
What is a stimulus in the context of homeostasis? Give one example.
A stimulus is a change in the internal or external environment detected by receptors. Example: A drop in body temperature due to cold wind.
Name the two main parts of the nervous system.
Central Nervous System (CNS) and Peripheral Nervous System (PNS).
True or False: Asexual reproduction always produces genetically identical offspring.
True—except when mutations occur during mitosis.
Which country invented paper?
China
Name the hormones secreted by the pancreas which help in the function of blood glucose regulation and explain their function.
Which endocrine gland secretes insulin, and what happens to glucose when insulin is released?
The pancreas secretes insulin. When insulin is released, glucose moves from the bloodstream into cells for energy or storage, lowering blood glucose levels.
What is the role of sensory neurons in the nervous system?
Sensory neurons detect changes in the environment and send impulses to the CNS.
Why is internal fertilisation generally considered a better survival strategy than external fertilisation?
Internal fertilisation protects gametes and embryos from drying out and predation, increasing survival chances.
Which planet has the most moons in our solar system?
Saturn
Explain how sweating helps maintain body temperature. What is the term for this cooling effect?
Sweating cools the body through evaporative cooling. Water and salts are released from sweat glands, and as water evaporates, it draws heat away from the body.
List one structural and one behavioral mechanism humans use to regulate body temperature.
Define gestation period and explain why it varies among animals.
Gestation period is the time from fertilisation to birth. It varies to maximise offspring survival—longer periods often mean more developed young.
Explain why species that provide more parental care tend to produce fewer offspring.
High parental care requires more energy per offspring, so fewer are produced (K-strategy).
What is the name of the largest desert in the world?
Antarctic desert
Describe the role of the hypothalamus in temperature regulation and how it uses negative feedback to maintain stability.
The hypothalamus detects changes in body temperature and coordinates a response via the nervous and endocrine systems. It sends signals to counteract the stimulus, restoring temperature to 37°C through negative feedback.
Explain why positive feedback is rare in the human body and give one example where it occurs.
Positive feedback amplifies a stimulus instead of reversing it. It’s rare because it moves the body away from homeostasis. Example: Oxytocin release during childbirth contractions.
What is spawning, and why does it require large numbers of gametes?
Spawning is external fertilisation where eggs and sperm are released into the environment. Large numbers of gametes are needed because many are lost or eaten.
Why is sexual reproduction usually an advantage in rapidly changing environments compared to asexual reproduction?
Sexual reproduction introduces genetic variation, helping populations adapt to changing conditions. Asexual reproduction lacks variation, making adaptation harder.
What is the smallest country in the world by land area?
The Vatican City
Scenario: Ava skips lunch and feels shaky by the end of the day. Explain the full negative feedback process that occurs in her body, including the stimulus, receptor, coordinating center, hormones involved, and the final response. Why is this considered negative feedback?
Scenario: Jasper plays soccer on a hot day and sweats heavily. Infer how his body integrates the nervous and endocrine systems to maintain temperature homeostasis. Include the role of blood vessels, sweat glands, and hypothalamus in your explanation.
The hypothalamus detects increased temperature and signals:
Scenario: A species reproduces through external fertilisation and provides no parental care. Predict the survival strategy this species uses and explain why this strategy evolved.
Species use an r-strategy: producing thousands of gametes to compensate for high mortality. This evolved because external fertilisation and no care result in low survival per individual.
Scenario: Compare two species—one with a long gestation period and high parental care, and another with short gestation and no parental care. Infer which species is more vulnerable to environmental change and justify your reasoning.
The species with short gestation and no care is more vulnerable because it relies on producing many offspring in stable conditions. Environmental change would drastically reduce survival, while the high-care species invests in fewer, adaptable offspring.
Which two countries share the longest international border?
Canada and the USA