B4 Organising Animals And Plants

Question 1

Name the four main components of blood.

Answer 1

red blood cells, white blood cells, plasma, platelets

Question 2

What is the function of platelets?

Answer 2

form blood clots - prevent the loss of blood and stop wounds becoming infected

Question 3

Why is the human circulatory system a double circulatory system?

Answer 3

blood passes through the heart twice for every circuit around the body - deoxygenated blood is pumped from the right side of the heart to the lungs, and the oxygenated blood that returns is pumped from the left side of the heart to the body

Question 4

How does the structure of an artery relate to its function?

Answer 4

carries blood away from the heart under high pressure - has a small lumen and thick, elasticated walls that can stretch

Question 5

How does the structure of a vein relate to its function?

Answer 5

carries blood back to the heart at low pressure -doesn’t need thick, elasticated walls, but has valves to prevent blood flowing the wrong way

Question 6

How does the structure of a capillary relate to its function?

Answer 6

carries blood to cells and tissues - has a one-cell-thick wall to provide a short diffusion distance

Question 7

List the structures air passes through when breathing in.

Answer 7

mouth/ nose - trachea-* bronchi- bronchioles -› alveoli

Question 8

What is the function of the red blood cells?

Answer 8

Bind to oxygen and transport it around the body

Question 9

What is the function of the white blood cells?

Answer 9

Defend the body against pathogens

Question 10

What is the function of the plasma?

Answer 10

Transports blood cells and substances around the body

Question 11

Why is a leaf an organ?

Answer 11

there are many tissues inside the leaf that work together to perform photosynthesis

Question 12

How is the upper epidermis adapted for its function?

Answer 12

• single layer of transparent cells allow light to pass through
• cells secrete a waxy substance that makes leaves waterproof

Question 13

How is the palisade mesophyll adapted for its function?

Answer 13

tightly packed cells with lots of chloroplasts to absorb as much light as possible for photosynthesis

Question 14

How is the spongy mesophyll adapted for its function?

Answer 14

air spaces increase the surface area and allow gases to diffuse quickly

Question 15

What is the function of the guard cells?

Answer 15

control the opening and closing of the stomata

Question 16

What is the function of the xylem?

Answer 16

transport water and mineral ions from the roots to the rest of the plant

Question 17

Give three adaptations of the xylem.

Answer 17

• made of dead cells
• no end wall between cells
• walls strengthened by a chemical called lignin to withstand the pressure of the water

Question 18

What is the function of the phloem?

Answer 18

transport dissolved sugars from the leaves to the rest of the plant

Question 19

What is the purpose of translocation?

Answer 19

transport dissolved sugars from the leaves to other parts of the plant for respiration, growth, and storage

Question 20

Define the term transpiration.

Answer 20

movement of water from the roots to the leaves through the xylem

Question 21

What is the purpose of transpiration?

Answer 21

• provide water to keep cells turgid
• provide water to cells for photosynthesis
• transport mineral ions to leaves

Question 22

Name four factors that affect the rate of transpiration.

Answer 22

temperature, light intensity, humidity, and wind speed

Question 23

What effect does temperature have on the rate of transpiration?

Answer 23

higher temperatures increase the rate of transpiration

Question 24

What effect does humidity have on the rate of transpiration?

Answer 24

higher levels of humidity decrease the rate of transpiration

Question 25

Why does increased light intensity increase the rate of transpiration?

Answer 25

stomata open wider to let more carbon dioxide into the leaf for photosynthesis

Question 26

What is the function of the stomata?

Answer 26

allow diffusion of gases into and out of the plant

Question 27

Where are most stomata found?

Answer 27

underside of leaves

Question 28

What is the advantage to the plant of having a high number of stomata at this location?

Answer 28

reduces the amount of water loss through evaporation