Chapter 4

Question 1

What does plasma carry (3)

Answer 1

red blood cells, white blood cells, platelets

Question 2

What makes up the human circulatory system (3)

Answer 2

blood, blood vessels, heart

Question 3

where is waste carbon dioxide carried to

Answer 3

the lungs

Question 4

where and how is urea formed

Answer 4

urea formed in your liver from the breakdown of excess proteins

Question 5

How are red blood cells adapted

Answer 5

biconcave discs so high volume to SA ratio
they are packed with a red pigment called haemoglobin that binds to oxygen
they have no nucleus, making more space for haemoglobin

Question 6

what do white blood cells do

Answer 6

help protect the body against infection

Question 7

what are platelets

Answer 7

they are cell fragments that start the clotting process at wound sites.

Question 8

what are the main types of blood vessels

Answer 8

arteries, veins, capillaries

Question 9

what do valves do

Answer 9

the valves prevent backflow, ensuring that blood flows in the right direction

Question 10

what do arteries do

Answer 10

your arteries carry blood away from your heart to the organs of your body

Question 11

what do veins do

Answer 11

the veins carry blood away from the organs towards your heart

Question 12

what do capillaries do

Answer 12

capillaries form a huge network of tiny vessels linking the arteries and the veins

Question 13

what is the heart

Answer 13

is an organ that pumps blood around the body

Question 14

what are stents used for

Answer 14

stents can be used to keep narrowed or blocked arteries open

Question 15

what do statins do

Answer 15

statins reduce cholesterol levels in the blood, reducing the risk of coronary heart disease.

Question 16

what happens in the heart 1) deoxygenated blood cycle

2) oxygenated blood cycle

Answer 16

1) deoxygenated blood enters the heart from the body -> right atrium -> right ventricle -> pulmonary artery which is going to the lungs
2) oxygenated blood enters the heart from the lungs through the pulmonary vein -> left atrium -> left ventricle -> aorta which takes blood to the body

Question 17

what can be done to damaged heart valves

Answer 17

they can be replaced using biological or mechanical valves

Question 18

what does a natural pacemaker do

Answer 18

the resting heart rate is controlled by a group of cells in the right atrium

Question 19

what does an artificial pacemaker do

Answer 19

they are electrical devices used to correct irregularities in the heart rhythm

Question 20

What does the alveoli do

Answer 20

The alveoli provide a very large surface area and a rich supply of blood capillaries. This means gases can diffuse into and out of the blood as efficiently as possible.

Question 21

describe the ventilation of the lungs (breathing in, breathing out)

Answer 21

(breathing in) 1) as ribs move up and out and diaphragm flattens, the volume of the chest increases
2) increased volume means lower pressure in the chest
3) atmospheric air at higher pressure than chest - so air is drawn into the lungs
(breathing out) 1) as ribs fall and diaphragm moves up, the volume of the chest gets smaller
2) decreased volume means increased pressure in the chest
3) pressure in chest higher than outside - so air is forced out of the lungs

Question 22

what do xylem tissue do

Answer 22

they transport water and mineral ions from the roots to the stems and leaves

Question 23

what do phloem tissue do

Answer 23

they transport dissolved sugars from the leaves to the rest of the plant, including the growing regions and storage organs

Question 24

what is transpiration

Answer 24

it is the loss of water vapour from the surface of plant leaves

Question 25

how is water lost

Answer 25

water is loss through the stomata, which open to let in CO2 for photosynthesis

Question 26

what controls gas exchange and water loss

Answer 26

the stomata and guard cells

Question 27

4 factors that increase the rate of transpiration

Answer 27

temperature, humidity, air flow, light intensity

Question 28

when is transpiration most effective

Answer 28

in hot, dry, windy or bright conditions