B3

Question 1

Osmosis

Answer 1

Osmosis is the movement of water molecules across a partially permeable membrane from a region of high concentration to a region of low concentration

Question 2

Diffusion

Answer 2

Diffusion is where particles move from an area of high concentration to an area of low concentration.

Question 3

Diffusion through cell membranes

Answer 3

The job of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide from it.

Question 4

Alveoli

Answer 4

In order for the lungs to transfer oxygen, they contain millions of little air sacs called alveoli where gas exchange takes place

Question 5

Adaptation of alveoli

Answer 5

An enormous surface area
A moist lining for dissolving gases
Very thin walls
A good blood supply

Question 6

Villi

Answer 6

Villi are found inside of the small intestine. They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood.

Question 7

Adaptations of villi

Answer 7

A single layer of surface cells

A very good blood supply to assist quick absorption

Question 8

Active transport

Answer 8

Active transport is where substances are absorbed from a low concentration to a high concentration (against the concentration gradient)

Question 9

Root hair cells

Answer 9

Root hair cells are specialised for absorbing water and minerals.

Question 10

Adaptations of root hair cells

Answer 10

The cells on the surface of plant roots grow into long “hairs” which stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil. Most of the water and mineral ions that get into a plant are absorbed by the root hair cells

Question 11

Active transport continued

Answer 11

We need active transport to stop us starving. It’s used in the gut when there is low concentration of nutrients in the gut, but a high concentration of nutrients in the blood.

Question 12

Active transport in the gut

Answer 12

When there’s a higher concentration of glucose and amino acids in the gut they diffuse naturally into the blood. However sometimes there’s a lower concentration of nutrients in the gut than there is in the blood. This means that the concentration gradient is the wrong way so active transport is used. Active transport allows nutrients to be taken into the blood, despite the fact that the concentration gradient is the wrong way.

Question 13

The lungs

Answer 13

You need oxygen from the air into your bloodstream so that it can get to your cells for respiration. You also need to get rid of carbon dioxide in your blood. This all happens inside the lungs. `

Question 14

Ventilation

Answer 14

Ventilation is breathing in and breathing out. When breathing in, intercostal muscles and diaphragm contract and the thorax volume increases. This decreases the pressure, drawing the air in. When breathing out, intercostal muscles and diaphragm relax. The thorax volume decreases which increases the pressure so air is forced out.

Question 15

Artificial ventilators

Answer 15

Artificial ventilators help people to breathe. They are machines that move air into or out of the lungs. They help people who can’t breathe by themselves e.g. if they’re under general anaesthetic, or have a lung injury or disease