Sec 2 WA3 Revision – Ecosystems, Electricity & Digestion

Question-and-answer flashcards covering Chapter 12 (Ecosystems & human impact), Chapter 13 (Electrical system), and Chapter 14 (Human digestive system).

What makes a resource ‘sustainable’?

It is always available and will not run out.

Name two visible effects of climate change caused by human activities.

Melting glaciers/ice caps and rising global sea levels.

How does deforestation contribute to climate change?

Burning forests releases greenhouse gases that trap heat.

Why is excessive food wastage harmful to the environment?

Resources used to produce, transport, and dispose food are wasted, and decaying food releases methane.

State one major consequence of contaminating freshwater supplies.

It further decreases the limited amount of freshwater available for use.

Give two actions individuals can take to conserve the environment.

(Any two) Take public transport, choose energy-efficient appliances, reduce/reuse/recycle plastics, prevent food wastage, support reforestation.

Define ‘habitat’.

The place where an organism lives.

What physical factor is measured with a light probe in a data logger?

Light intensity.

Give one structural adaptation of a penguin and its function.

Flippers allow rapid movement in water; fat layer keeps it warm.

Why do rainforest trees grow very tall?

To compete for sunlight in warm, humid, high-rainfall conditions.

What soil characteristic is typical of mangrove swamps?

Soil is high in salt and low in oxygen.

Define ‘population’ in ecology.

A group of organisms of the same kind living in the same environment.

What type of interrelationship exists between bees and flowers?

Mutualism – both parties benefit.

Give one adaptation that helps prey avoid predators.

Camouflage (or high speed, spikes, shells, etc.).

Why is the flow of energy in a food chain described as non-cyclical?

Energy is lost as heat at each stage and is not recycled.

What role do decomposers play in nutrient cycling?

They break down faeces and dead organisms, returning nutrients to the environment.

State the SI unit for electric current and the instrument used to measure it.

Ampere (A); measured with an ammeter.

How is a voltmeter connected in a circuit?

In parallel across the component.

What happens to current when resistance increases, assuming constant voltage?

Current decreases.

Name one material with low electrical resistance used for wiring.

Copper (or silver).

State a useful application of the heating effect of an electric current.

Infant incubators or sterilisers that convert electrical energy to heat.

Why can overloading a socket start an electrical fire?

A very large current flows, causing wires to overheat.

What safety device melts to break a circuit when current exceeds a set value?

A fuse.

Which wire in a three-pin plug is green and yellow, and what is its purpose?

Earth wire; it directs fault current safely to the ground.

Define electrical power and give its SI unit.

Rate of electrical energy conversion per unit time; unit is watt (W).

Give two ways to reduce household electricity consumption.

Buy appliances with ≥3 energy ticks; switch off appliances/air-con/water heater and sockets when not in use.

What is the main function of carbohydrates after digestion?

Provide energy for respiration.

Name the enzyme group that breaks proteins into amino acids.

Proteases.

Where does the digestion of fats begin in the human digestive tract?

Small intestine (due to lipases).

What is absorbed in the large intestine?

Remaining water and mineral salts.

State one symptom that can indicate diabetes.

Frequent urination (others: constant hunger, slow wound healing, etc.).

Give one lifestyle habit to lower the risk of diabetes.

Exercise regularly (others: balanced diet, regular health screening, avoid smoking/alcohol).

What causes constipation in terms of water absorption?

Faeces remain in the large intestine too long, so too much water is absorbed.

What is gastritis and one common cause?

Swelling/inflammation of the stomach lining; can be caused by bacterial infection or poor lifestyle habits (e.g., skipping meals, excess alcohol).

How can food poisoning be prevented when buying canned food?

Do not consume food from dented or bloated cans; check expiry dates.

State one benefit of bacteria in the human gut.

Boosts immune system (others: aids absorption of nutrients and minerals, helps produce foods like yoghurt).