B1- Cell structure and transport

Question 1

Conversion from cm to nanometres

Answer 1

1cm= 1millim
1millim= 1000 micrometres
1 micrometre= 100 nanometres

1 nanometres (1 X 10^-7m)

Question 2

Light microscope benefits:

Answer 2

• can magnify x200
• can view live specimen
• quite cheap
• easy to store

Question 3

Electron microscope:

Answer 3

• can magnify x2 000 000
• must be stored under certain temp and pH
• can give 3d images

Question 4

Animal cell structures:

Plant cell structures:

Answer 4

nucleus: controls cell activities
cytoplasm: chemical reactions take place
ribosomes: protein synthesis
cell membrane: controls passage of substances in and out cell
mitochondria: respiration

chloroplasts: photosynthesis
cell wall: made of cellulose strength
vacuole: support cell and keep it rigid

Question 5

Eukaryotic cells:

Answer 5

• plant and animal cells

- cell membrane and a cytoplasm and DNA is contained to a nucleus

Question 6

Prokaryotic cells:

Answer 6

• bacteria
• cell membrane and cytoplasm but DNA not contained to a nucleus
• forms dna loop called plasmids

Question 7

Sperm cell function and specialisation:

Answer 7

-swim through water to the egg cells and break through the outer layer of the egg

• tail to help swim
• middle section with lots of mitochondria for respiration
• acrosome contains digestive enzymes needed to break the egg
• large nucleus which contains genetic info needed to be passed on

Question 8

Nerve cell adaptions:

Answer 8

dendrites at the top which help make connections to other nerve cells

• long axon (body) to help it carry the impulse
• synapse contains lots of mitochondria which provide energy needed to make transmitter chemicals

Question 9

Muscle cell adaptions:

Answer 9

• need to contract and relax
• special proteins which slide over each other
• lots of mitochondria which transfer energy needed to contract and relax
• contain glycogen which can be broken down into glucose for respiration

Question 10

Root hair cells adaptions:

Answer 10

• increase in SA which allow more water to move into cell
• large vacuole which speeds up the rate of osmosis
• lots of mitochondria which transfer energy for active transport

Question 11

Xylem cells:

Answer 11

• transport tissue which carry water and mineral ions around the plant
• dead cells which form hollow tubes which allow water and mineral ions to flow through them
• reinforced by spiralled lignin which make it strong and help it withstand the pressure of water

Question 12

Phloem cells:

Answer 12

• transport food made from photosynthesis to the different plant cells
• cell wall breaks down to form sieve plates which allow water carrying dissolved foods to move through them

Question 13

What is diffusion?

Answer 13

net movement of particles in a solution or gas from an areas of high concentration to an area of low concentration

Question 14

What affects the rate of diffusion?

Answer 14

• temperature
• concentration gradient
• SA to Volume ratio

Question 15

What osmosis?

Answer 15

net movement of a solvent (water) through a partially permeable membrane from an area of high water concentration to an area of low water concentration

Question 16

What does concentrated and dilute mean?

Answer 16

concentrated- high concentration of solutes and low water concentration
dilute- low concentration of solutes and high concentration of water

Question 17

What does:
isotonic
hypertonic
hypotonic mean?

Answer 17

isotonic- concentration of the solutes are the same

hypertonic- concentration of solutes higher outside (low water concentration)
-water leaves cell

hypotonic- concentration of solutes lower outside (high water concentration)
-water enters cell

Question 18

Why is osmosis needed in animals?

Answer 18

• osmosis balances water in the cytoplasm

- can cause big problems as water can enter cells and cause them to burst

Question 19

Why do plants need osmosis?

Answer 19

• plants rely on osmosis to support the leaves
• water moves into plants and causes vacuole to swell up and press against the cytoplasm
• pressure build up until no more water can enter
• known as turgor pressure

Question 20

What do plants need the outside solution to always be?

Answer 20

hypotonic

Question 21

What is the term when water enters the plant?

Answer 21

plasmolysis

Question 22

What is active transport?

Answer 22

the movement of solutes from an area of low concentration to an area of high concentration
(against the concentration gradient)

Question 23

How do dissolved substances move?

Answer 23

-diffusion and active transport

Question 24

Where does the energy needed for active transport come from?

Answer 24

energy is needed to carry molecules across a membrane then to the original position- from respiration

Question 25

Where is active transport used in animals and plants?

Answer 25

• plants: root hair cells

- animal: cells lining gut- glucose absorbed out of gut into kidney tubules- glucose needed for respiration