B3.1 Movement of Molecules into and Out of Cells NOT FINISHED

Question 1

What is osmosis?

Answer 1

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

Question 2

What is a partially permeable membrane?

Answer 2

A membrane with very small holes in it

Question 3

What is osmosis a form of?

Answer 3

Diffusion

Question 4

What is tissue fluid?

Answer 4

A solution mixed with water, oxygen and glucose dissolved in it - Tissue fluid surrounds the cells in the body

Question 5

What happens when there is a difference in concentration of water in the tissue fluid and the cell?

Answer 5

If the water concentration in the tissue fluid is greater than the water in the cell, then water will move from the dilute tissue fluid to the concentrated cell via osmosis (and vice versa)

Question 6

What is osmosis trying to achieve?

Answer 6

Equilibrium

Question 7

When you exercise what do you lose in your sweat?

Answer 7

Ions and water

Question 8

What happens if the balance between water and ions in the body is wrong?

Answer 8

It could result in the cells having too much or too little water in them - having the wrong amount of water can damage cells or mean they don’t work as well

Question 9

Why do sports drink contain water, sugar and ions?

Answer 9

Because they replenish the water and ions you lose in sweat and replace the sugar used up by the muscles during exercise

Question 10

How do you evaluate claims made about sports drinks? (4)

Answer 10

Ask yourself:
Is the claim from a scientific study, published in a reputable journal?
Was it written by a qualified person who is not connected with the sellers?
Was the sample of people asked/tested large enough?
Have there been other studies which found similar results?

Question 11

What is active transport?

Answer 11

The movement of particles against a concentration gradient (low concentration to high concentration) using energy released from respiration

Question 12

Give an example of where active transport occurs

Answer 12

In the digestive - when there is a low concentration of nutrients in the gut and a high concentration of nutrients in the blood, this is essential to stop us from starving

Question 13

What does active transport need to work?

Answer 13

Energy from respiration

Question 14

What does active transport allow cells to do?

Answer 14

Absorb ions from very dilute solutions

Question 15

Why is there a constant movement of substances in the body?

Answer 15

Because cells need substances to work and also need waste substances removed

Question 16

In life processes, what do substances have to move through?

Answer 16

An exchange surface

Question 17

How are exchange surfaces adapted to maximise efficiency?

Answer 17

They are thin, so substances only have a short distance to diffuse, they have larges surface areas so lots of substances can diffuse at once, ES in animals have lots of blood vessels to get stuff in and out of the blood quickly and gas exchange surfaces in animals are usually ventilated - air moves in and out

Question 18

How does the exchange of substances work in single-celled organisms?

Answer 18

Substances are directly exchanged with the environment across their outer surface

Question 19

Why are specialised organ systems needed for exchanging materials in bigger, complex organisms?

Answer 19

Because where the substance is needed ends up being far away from exchange surfaces

Question 20

What is the job of the lungs?

Answer 20

To transfer oxygen to the blood and remove carbon dioxide from the blood

Question 21

Where does gas exchange take place in the lungs?

Answer 21

In little air sacs called alveoli

Question 22

Why does oxygen diffuse into the alveoli and into the capillaries?

Answer 22

Because there is a greater concentration of oxygen in the air than in the alveoli, and from there, there is a greater concentration of oxygen in the alveoli than in the blood so oxygen diffuses into capillaries

Question 23

Why does carbon dioxide diffuse into alveoli from the blood?

Answer 23

Because there is a greater concentration of carbon dioxide in the blood than in the alveoli

Question 24

How does air enter and leave the alveoli?

Answer 24

Through small tubes called bronchioles

Question 25

How are the alveoli adapted to maximise the diffusion of oxygen and carbon dioxide? (4)

Answer 25

They have a large surface area, a moist lining for dissolving gases, very thin walls and a good blood supply

Question 26

Where and how are glucose and amino acids absorbed into the bloodstream?

Answer 26

The small intestine - either by diffusion or active transport

Question 27

How is the absorption of nutrients assisted in the small intestine?

Answer 27

The inside of the small intestine is covered in millions of tiny little projections called villi

Question 28

How do the villi aid absorption in the small intestine? (3)

Answer 28

They increase the surface area of the small intestine (so food is absorbed quicker), they have a very good blood supply to assist quick absorption and have a single layer of surface cells