B2a - Cells, Organs and Populations

Question 1

What is the function of the nucleus?

Answer 1

It contains genetic material that controls the activities of the cell.

Question 2

What is the cytoplasm?

Answer 2

A gel-like substance where most of the chemical reactions. Therefore, it contains enzymes.

Question 3

Where do most chemical reactions occur in a cell?

Answer 3

The cytoplasm.

Question 4

What is the function of the cell membrane?

Answer 4

It holds the cells together and controls what goes in and out.

Question 5

What are mitochondria?

Answer 5

Where most of the reactions for respiration occur.

Question 6

What are ribosomes?

Answer 6

Where proteins are made in the cell.

Question 7

What controls the activities in the cell?

Answer 7

The nucleus.

Question 8

Where are proteins made in the cell?

Answer 8

The ribosomes.

Question 9

Where do most reactions for respiration occur in the cell?

Answer 9

Mitochondria.

Question 10

What three features does a plant cell have that an animal cell does not?

Answer 10

Cell wall, permanent vacuole, chloroplasts (sometimes).

Question 11

What is the cell wall made of in a plant cell?

Answer 11

Cellulose.

Question 12

What is the function of the cell wall?

Answer 12

To support and strengthen the cell.

Question 13

What does the permanent vacuole contain?

Answer 13

Cell sap - a weak solution of sugar and salts.

Question 14

What do chloroplasts contain?

Answer 14

Chlorophyll.

Question 15

What do chloroplasts do?

Answer 15

They are where photosynthesis occurs.

Question 16

What is yeast?

Answer 16

A single-celled microorganism.

Question 17

What features does a yeast cell have?

Answer 17

Nucleus, cytoplasm, cell membrane, cell wall.

Question 18

What features does a bacterial cell have?

Answer 18

Cytoplasm, cell membrane, cell wall. The genetic material floats in the cytoplasm because bacterial cells do not have nuclei.

Question 19

What is diffusion?

Answer 19

Diffusion is the spreading out of particles from an area of high concentration to an area of low concentration.

Question 20

In which substances does diffusion occur and why?

Answer 20

Solutions and gases because the particles are free to move about randomly.

Question 21

What is the relationship that links concentration and diffusion?

Answer 21

The bigger the difference in concentration, the faster the rate of diffusion.

Question 22

How do dissolved substances move in and out of cells?

Answer 22

By diffusing through the cell membrane.

Question 23

What are some examples of molecules that diffuse through the cell membrane?

Answer 23

Oxygen, glucose, amino acids, water.

Question 24

Where is a palisade cell located in the leaf?

Answer 24

The upper layer (closest to the light).

Question 25

Which cells are at the top of the leaf?

Answer 25

Palisade leaf calls.

Question 26

What do palisade cells contain lots of?

Answer 26

Chloroplasts.

Question 27

Why do palisade leaf cells have a tall shape?

Answer 27

The tall shape of a palisade cell means more surface area is available at the sides for absorbing carbon dioxide from the air in the leaf.

Question 28

Why are palisade cells thin?

Answer 28

To fit more of them in the top of the leaf.

Question 29

Why are guard cells kidney shaped?

Answer 29

To open and close the stomata in the leaf.

Question 30

How do guard cells open the stomata in a leaf?

Answer 30

When the plant has lots of water, the guard cells fill with it, which causes them to go plump and turgid. This makes the stomata open so gases can be exchanged for photosynthesis.

Question 31

How do guard cells close the stomata in a leaf?

Answer 31

When the plant is short of water, the guard cells lose water and become flaccid, making the stomata close to prevent loss of water vapour.

Question 32

How are guard cells adapted to prevent water loss from the leaf?

Answer 32

They are sensitive to light so shut the stomata at night.

Question 33

How are red blood cells adapted to carry oxygen?

Answer 33

They have a concave shape for a larger surface area to absorb more oxygen/pass smoothly through capillaries; they have lots of haemoglobin; they have no nucleus to fit more haemoglobin.

Question 34

What is haemoglobin?

Answer 34

The pigment in red blood cells that absorbs oxygen.

Question 35

How is an egg cell specialised for reproduction?

Answer 35

It has huge energy reserves to support the embryo; when the sperm fuses with the egg, the egg's membrane changes structure to prevent more sperm getting in and giving the embryo excess DNA.

Question 36

How is a sperm cell specialised for reproduction?

Answer 36

The long tail and streamlined head allows it to get to the egg; it contains lots of mitochondria for energy; it has enzymes in its head that allows it to digest through the egg cell membrane.

Question 37

Why do sperm cells have enzymes in their heads?

Answer 37

To digest through the egg cell membrane.

Question 38

What are large multicellular organisms made up of?

Answer 38

Organ systems.

Question 39

What is the process by which cells become specialised called?

Answer 39

Differentiation.