B2

Question 1

What is diffusion?

Answer 1

The net movement of particles from a high concentration to a low concentration

Question 2

What three factors affect the rate of diffusion?

Answer 2

Distance
Surface area
The concentration gradient

Question 3

Which three places does diffusion occur in the body?

Answer 3

Oxygen and glucose diffusion
Toxic products diffusion
Particle movement

Question 4

What is lysis?

Answer 4

The name given to when a red blood cell bursts

Question 5

What is osmosis?

Answer 5

The net movement of water molecules from a high water potential to a low water potential

Question 6

What is an example of a plasmolysed cell?

Answer 6

When a plant cell collapses away from its wall because of water loss

Question 7

What is active transport?

Answer 7

It uses ATP and carrier proteins to allow cells to move from an area of low concentration to a high concentration

Question 8

Why is mitochondria needed for active transport?

Answer 8

Respiration produces ATP, which the cell uses during active transport to change the shape or rotate the carrier protein

Question 9

Explain the digestion example of active transport

Answer 9

In the small intestine, carbohydrates are broken down into glucose. The glucose is actively transported through the villi, to the bloodstream where it is carried to wherever it is needed.

Question 10

What is mitosis?

Answer 10

The process by which body cells divide to replace damaged or old cells, and to enable an organism to grow

Question 11

Explain the stages of mitosis

Answer 11

The DNA is copied, so that there are 2 copies of each chromosome
The chromosomes align in the centre of the cell
The chromosomes are separated to opposite sides of the cell
Nuclei form around them
The cell separates into 2 daughter cells

Question 12

What is differentiation?

Answer 12

To become specialised to perform a specific job

Question 13

Name 5 examples of cells that become so specialised they only perform one function

Answer 13

Fat cells 
Palisade cells 
Sperm cells 
Red blood cells 
Ciliated cells

Question 14

What is a stem cell?

Answer 14

An undifferentiated cell which can become specialised and can develop into any type of specialised cell and form all types of tissues and organs

Question 15

What are the differences between embryonic stem cells and adult stem cells?

Answer 15

Embryonic stem cells
Found in embryos
Can differentiate into all cell types

Adult stem cells
Found in various body tissues
Can only differentiate into some different types of cell

Question 16

What places are adult stem cells found?

Answer 16

Bone marrow, brain, skin, liver

Question 17

Why do adult stem cells act as a repair mechanism?

Answer 17

They remain no dividing for years. Only dividing if activated by disease or tissue damage

Question 18

Where are stem cells found in plants?

Answer 18

The meristems

Bud, root tips, shoot tips

Question 19

What is water potential

Answer 19

The concentration of free water molecules

Question 20

How are ciliated cells adapted

Answer 20

Between ciliated cells there are goblet cells which secrete mucus that traps dirt and bacteria
Cilia hairs sweep the mucus to the back of the throats where it is swallowed and destroyed in the stomach

Question 21

How are palisade cells adapted

Answer 21

Found near the surface of the leaf
Packed full of chloroplast
Regular shape to allow close packing
Maximising the absorption of light

Question 22

Why is it more difficult for multicellular organisms to exchange substances?

Answer 22

Diffusion does not occur quick enough to support life
Low surface area to volume ratio
Some cells are deep inside the organism and would need to travel a long distance