Fundamental biology concepts and principles

Question 1

Students should be able to explain how meiosis

Answer 1

halves the number of chromosomes in gametes and fertilisation restores the full number of chromosomes.

Question 2

Cells in reproductive organs divide by meiosis to form

When a cell divides to form ——-:

Answer 2

gametes

gametes

copies of the genetic information are made
* the cell divides twice to form four gametes, each with a single set of
chromosomes
* all gametes are genetically different from each other.

Question 3

variation occurs when

Answer 3

gametes fuse at fertilisation

Question 4

Students should understand that meiosis leads to

while mitosis leads to

Answer 4

non-identical cells being formed

identical cells being formed.

Question 5

Sexual reproduction involves the joining (fusion) of male and female gametes:

Answer 5

• sperm and egg cells in animals
• pollen and egg cells in flowering plants.

Question 6

In sexual reproduction there is mixing of genetic information which leads to

Answer 6

variety in the offspring

Question 7

Asexual reproduction involves:

This leads to

Answer 7

only one parent and no fusion of gametes. There is no mixing of genetic information.

genetically identical offspring (clones).

Question 8

recall that many different materials cycle through the

Answer 8

abiotic and biotic components of an ecosystem

Question 9

All materials in the living world are recycled to provide the

Answer 9

building blocks for future organisms.

Question 10

The carbon cycle returns

Answer 10

carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis.

Question 11

The water cycle provides

Answer 11

fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated.

Question 12

Students should be able to explain the role of microorganisms in cycling materials through an ecosystem by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.

Answer 12

Role of Microorganisms in Cycling Materials

Decomposition:

Microorganisms like bacteria and fungi act as decomposers.
They break down dead plants, animals, and waste into simpler substances.
Releasing Carbon Dioxide:

During decomposition, microorganisms respire, using carbon compounds from dead organisms as food.
This releases carbon dioxide (CO₂) back into the atmosphere, which plants can reuse for photosynthesis.
Returning Mineral Ions to the Soil:

Decomposers also break down materials into mineral ions, such as nitrates and phosphates.
These ions enrich the soil and provide nutrients for plant growth.
Ecosystem Balance:

By recycling nutrients and carbon, microorganisms keep ecosystems healthy and productive.
Without them, dead organisms would pile up, and plants wouldn’t get the nutrients they need to grow.