Aqa Igcse Biology. Key Facts Chapter 2

Front 1

Why is cell division necessary?

Back 1

For growth and repair

Front 2

How many cells are produced in mitosis?

Back 2

Two identical cells are produced from the original cell

Front 3

What do chromosomes contain?

Back 3

Genes which need to be passed on to each new cell

Front 4

What happens in mitosis?

Back 4

A copy of each chromosome is made before the cell divides and one of each chromosome goes to each new cell.

Front 5

What are stem cells?

Back 5

Unspecialised cells are called stem cells.

Front 6

What happens to differentiated cells which cannot divide?

Back 6

They are replaced with adult stem cells, such as the ones found in bone marrow.

Front 7

For how long can plant cells differentiate?

Back 7

Plant cells can differentiate throughout the life of the plant as it continues to grow.

Front 8

What are actively dividing plant tissues called?

Back 8

Meristems

Front 9

By which form of division are cells of offspring produced by asexual reproduction produced by?

Back 9

Mitosis from the parent cell

Front 10

How do cells in reproductive organs divide to form gametes?

Back 10

They divide by meiosis

Front 11

How many chromosomes from each pair of chromosomes do gametes have?

Back 11

Only one chromosome from the original pair

Front 12

Why does sexual reproduction result in variation?

Back 12

The gametes from each parent fuse so half the genetic information comes from the mother and half from the father.

Front 13

What happens in meiosis?

Back 13

Before each division a copy of each chromosome is made. The cell divides twice to form four gametes.

Front 14

Where are stem cells found?

Back 14

In the human embryo and adult bone marrow

Front 15

What do stem cells have the potential to do in science?

Back 15

To treat previously incurable diseases. We may be able to grow nerve cells to cure paralysis or whole new organs for people who need them

Front 16

What is a tumour

Back 16

A mass of abnormally growing cells .

Front 17

What are benign tumours?

Back 17

Tumours that form in one place and do not spread to other tissues

Front 18

What are malignant tumours?

Back 18

Tumours that can spread to healthy tissue. Some malignant cells may enter the bloodstream and circulate to other parts of the body, forming secondary tumours.

Front 19

What are carcinogens?

Back 19

Cancer causing chemicals, including asbestos and the chemicals found in tobacco smoke.

Front 20

What might ionising radiation do?

Back 20

Cause cancer tumours to form

Front 21

What is a tissue?

Back 21

A group of cells with a similar structure and function.

Front 22

Give some examples of animal tissues

Back 22

Muscular tissue, which can contract to bring about movement.

Glandular tissue, to produce substances such as enzymes or hormones.

Epithelial tissue, which covers some parts of the body.

Front 23

Give some examples of plant tissue

Back 23

Epidermal tissue, which covers the plant.

Palisade mesophyll, which contains many chloroplasts and can photosynthesise.

Spongy mesophyll, which has some chloroplasts, many air spaces between cells and a large SA for diffusion of gasses.

Xylem and phloem which transport substances around the plant.

Front 24

What are organs made up of?

Back 24

Tissues

Front 25

What is the stomach made up of?

Back 25

Muscular tissue, to churn the stomach contents.

Glandular tissue, to produce digestive juices.

Epithelial tissue, to cover the outside and inside of the stomach.

Front 26

Give some examples of organs in plants

Back 26

The leaf, stem and root

Front 27

What are multicellular organisms made up of?

Back 27

Organ systems which work together

Front 28

What are organ systems made up of?

Back 28

several organs that work together to perform a particular function.

Front 29

What is the digestive system responsible for?

Back 29

Changing the food you each from insoluble molecules into soluble molecules and absorbing them into the blood.