B2

Question 1

Definition of diffusion

Answer 1

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration

Question 2

Definition of active transport

Answer 2

Movement of particles across a membrane against a concentration gradient

Using ATP released during respiration

Question 3

Osmosis

Answer 3

Net movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration

Question 4

Define turgid

Answer 4

Plump and Swollen

Question 5

Define Flaccid

Answer 5

Droopy

Question 6

How do you investigate osmosis

Answer 6

Cut equal cylinders of potato
Divided into groups of three
Place one group in each solution
Leave cylinders in solution at least 40 minutes
Remove cylinders and pat dry gently with paper towel
We each group again and record your results
Calculate percentage change in mass for each group

Question 7

Ideal exchange surface

Answer 7

The rate of diffusion osmosis and active transport is higher in cells with a larger surface area to volume ratio

Question 8

How does concentration gradient affect speed of exchange

Answer 8

Substances move in an hour or so faster if there’s a big difference in concentration between inside and outside of cell

Question 9

Properties of exchange surfaces

Answer 9

Thin (short travel distance)

Light surface area so lots of services can move at once

Exchange surfaces in animals have a lots of blood vessels to get stuck into and out of blood quickly

Gas exchange surfaces and animals that are often ventilated

Question 10

Examples of exchange surfaces

Answer 10

Alveoli And villi

Question 11

How are you specialise to maximise the diffusion of oxygen and carbon dioxide

Answer 11

Lives abroad so there is a large surface area for diffusion

They are also doing which means gases only have to travel a short distance

There are spaces inside of the leaf this lets gases to move easily between cells

In the lower surface is full of little holes called stomata

Question 12

How do you fruit has taken the water and mineral ions

Answer 12

Each branch of a route is covered in millions of microscopic routers which gives the blinds a big surface area for absorbing water and mineral ions from the soil water is absorbed through osmosis and minerals move in active transport

Question 13

Advantages of double circulatory system

Answer 13

Returning oxygenated blood to the heart means blood can be pumped around the body high-pressure

Increases bloodflow to tissues

Important for mammals because they use up a lot of oxygen maintain body temperature

Question 14

How is the heart provided to this energy

Answer 14

Muscle cells contain loads of mitochondria to provide cells of ATP

Question 15

What are all the vessels of the heart

Answer 15

On the right:Pulmonary artery and Veena Carver

On the left:Aorta and pulmonary vein

Question 16

Arteries

Answer 16

These carry blood away from the hear
Strong and elastic walls due to high pressure
Thick walls in comparison to lumen
Contain thick muscle layer
Branch into arterioles

Question 17

Capillaries

Answer 17

These are involved in the exchange of materials at the tissues
Arterial is branch into capillaries
Thin wall only one cell thick
Very small lumen

Question 18

Veins

Answer 18

Carry blood to the heart
Contain valves
Large lumen
Elastic fibres and smooth muscle

Question 19

What is inside blood

Answer 19

Red blood cells
White blood cells
Platelets
Plasma

Question 20

What does does plasma carry

Answer 20

Red blood cells
Water
Food products
CO2
Urea
Hormones
Antibodies

Question 21

Phloem

Answer 21

Made of columns of living cells called tube elements these have perforated end-plates to allow stuff to flow through
Drive tube elements have no nucleus this means they can’t survive on their their own nu so each sieve tube elements has a companion cell.
Transport food substances both up and down the stem to growing and storage tissues. This movement of food substances around plant is known as translocation

Question 22

Xylem

Answer 22

Made of dead cells with one hole

Thick side walls are made of cellulose. They’re strong and stiff which gives plant support
They carry water and minerals from roots up the shoot to leaves in the transpiration stream

Question 23

What affects transpiration

Answer 23

Light intensity (increases rate of photosynthesis so stomata open)
Temperature (water particles move more)
Air movement (if air still water vapour surrounds leaf which means slower diffusion)

Question 24

How do Plants control water loss

Answer 24

Leaves usually have waxy cuticle
Stomata on underside of leaf where it’s darker and cooler
Plants that need to conserve water have smaller and fewer stomata

Question 25

When do stomata close

Answer 25

When supplies of water dry up

Question 26

How do stomata open and close

Answer 26

The guard cells Have a special kidney shape which opens and close the stomata as the Guard cells go turgid of flaccid

Open during the day and close at night