IGCSE · Practice questions · Characteristics of living organisms

Define it exactly.

Six original Cambridge-style questions on movement, respiration, sensitivity, growth, reproduction, excretion and nutrition, and on deciding whether something is alive.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

Keep these straight

Learn the definitions word for word.

MRS GREN: movement, respiration, sensitivity, growth, reproduction, excretion, nutrition.
Respiration is chemical reactions in cells that release energy; it is not breathing.
Growth is a permanent increase in size and dry mass.
Alive means all seven, carried out by the organism's own cells.

Recall

[3 marks]

Define (a) sensitivity, (b) nutrition and (c) reproduction, as characteristics of living organisms.

(a) The ability to detect and respond to changes in the internal or external environment. ✓
(b) The taking in of materials for energy, growth and development. ✓
(c) The processes that make more of the same kind of organism. ✓

Explain

[2 marks]

A student writes: “Plants do not respire, because they have no lungs.” Explain why the student is wrong.

Respiration is the chemical reactions in cells that break down nutrient molecules and release energy; it is not breathing. ✓
Every living plant cell respires all the time, so plants respire even though they have no lungs. ✓

Explain

[2 marks]

A dry pea seed is soaked in water for a day and becomes much larger. Explain whether this is growth.

Growth is a permanent increase in size and dry mass. ✓
The extra size is water, which is not dry mass and can be lost again, so this is not growth. ✓

Analysis

[3 marks]

A robot vacuum cleaner moves around a room, detects walls and turns away, and is charged with electricity each night. Use three characteristics of living organisms to explain why it is not alive.

Respiration: it releases energy from a battery, not by chemical reactions in cells breaking down nutrient molecules. ✓
Growth: it never increases permanently in size and dry mass. ✓
Reproduction: it cannot make more of the same kind of robot. (Also accept: no excretion of waste products of metabolism.) ✓

Recall

[2 marks]

Name two substances that are excreted by a mammal and state where each one leaves the body.

Carbon dioxide, from respiration, leaves through the lungs in breathed-out air. ✓
Urea leaves through the kidneys in urine. ✓

Explain

[3 marks]

A rose bush stays rooted in one place. Describe how it shows (a) movement, (b) excretion and (c) nutrition.

(a) Parts of the plant change position: flowers open and close, and leaves turn towards the light. ✓
(b) It removes waste products of metabolism, such as oxygen from photosynthesis, through its leaves. ✓
(c) It takes in carbon dioxide and water for photosynthesis, and mineral ions from the soil, for energy, growth and development. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.