Cellular Organisation (UNIT 2)

Question 1

CELL DIFFERENTIATION

Answer 1

The process by which each cell becomes specialised in structure to suit the role that it will carry out.

Question 2

Where do all cells in an organism derive from?

Answer 2

mitotic division of the fertilised egg.

They all have the same genes.

Question 3

How does a cell differentiate?

Answer 3

Every cell contains the genes needed for it to develop into any one of the many different cells in an organism. But only a few of these genes are are switched on (expressed) in any one cell. Different genes are switched on in each type of differentiated cell. The rest are switched off.

Question 4

TISSUE

Answer 4

A group of similar cells organised into a structural unit that perform a specific function

Question 5

Give two examples of tissues. Describe.

Answer 5

• Epithelial tissues, found in animals and consist of sheets of cells. They line the surfaces of organs and often have a protective or secretory function.
• Xylem- Occur in plants and is made up of a number of cell types. Used to transport water and mineral ions throughout the plant and also gives mechanical support.

Question 6

ORGAN

Answer 6

A combination of tissues that are coordinated to perform a variety of functions.

Question 7

Explain how the tissues in the stomach work to digest food.

Answer 7

• Muscle to churn and mix the stomach contents,
• Epithelium to protect the stomach wall and produce secretions.
• Connective tissue to hold together the other tissues.

Question 8

Describe and explain the tissues that make up a leaf(organ)

Answer 8

• Palisade mesophyll made up of leaf palisade cells, that carry out photosynthesis.
• Spongy mesophyll adapted for gaseous exchange
• Epidermis to protect the leaf and allow gaseous diffusion.
• Phloem to transport organic materials away from the leaf.
• Xylem to transport water and ions into the leaf.

Question 9

Organ systems

Answer 9

Multiple organs working together to perform a particular function.

Question 10

Describe 3 organ system in humans.

Answer 10

• DIGESTIVE SYSTEM- digests and processes food. Made up of organs that include the salivary glands, oesophagus, stomach, duodenum, ileum, pancreas and liver.
• THE RESPIRATORY SYSTEM- is used for breathing and gas exchange. It is made up of organs that include the trachea, bronchi and lungs.
• THE CIRCULATORY SYSTEM- pumps and circulates blood. It is made up of organs that include the heart, arteries and veins.