CB8

Question 1

Name two human excretory organs?

Answer 1

1. Kidneys (Remove Urea)
2. Lungs (Get rid of Carbon Dioxide)

Question 2

What is a human excretory organ?

Answer 2

An organ in humans that expels waste minerals that have been produced inside an organism.

Question 3

How do substances move in and out of parts of the body?

Answer 3

By diffusion.

Question 4

What do the surfaces in the body have to ensure a lot of particles diffuse quickly?

Answer 4

1. They are thin (so particles don’t have to diffuse very far)
2. They have a large surface area (so that there is more room for particles to diffuse)

Question 5

What is a capillary?

Answer 5

A tiny blood vessel with thin walls to allow for the transfer of substances between the blood and tissues.

Question 6

Where are capillaries found?

Answer 6

In the circulatory system.

Question 7

How does a cell’s surface area affect the diffusion of a substance?

Answer 7

The larger a cell’s surface area, the more of a substance can diffuse into (and out of) it in a certain time. However, if a cell’s volume is too big, the cell cannot fill up with all the materials it needs quickly enough.

Question 8

What is surface area : volume ratio?

Answer 8

Surface area / volume

Question 9

How is surface area : volume ratio useful?

Answer 9

It shows that the bigger the ratio, the more surface area something has per unit volume. As cells get bigger, their SA:V ratio gets smaller. If the ratio gets too small, a cell cannot get enough raw materials fast enough. So, there is a limit to the size of cells.

Question 10

Is the SA:V ratio of organs that move substances into and out of the body large or small?

Answer 10

Organs that move substances into and out of the body have large SA:V ratios.

Question 11

Why do human lungs have very large surface area?

Answer 11

As lungs are packed with millions of alveoli, which increase the surface area and so increase the speed and amount of gas exchange.

Question 12

Where does blood flow in the circulatory system?

Answer 12

Blood flows away from the heart into arteries.

Question 13

What is the circulatory system?

Answer 13

The system that moves blood around the body.

Question 14

How does blood return to the heart?

Answer 14

Blood returns to the heart in veins.

Question 15

What does the circulatory system consist of?

Answer 15

It consists of the heart, arteries, veins and capilaries.

Question 16

Where is the blood carried from the heart (detailed circulatory system)?

Answer 16

1. To the arteries (they take blood away from the heart)
2. They then go to capillaries tissues
3. They then go to the veins (they start to carry blood back to the heart)

Question 17

Describe the arteries.

Answer 17

• It is a narrow tube
• Thick layer of elastic and muscle fibres

Question 18

Describe the capillaries (in tissues).

Answer 18

• It is a very narrow tube
• Wall is only one cell thick

Question 19

Describe the veins.

Answer 19

• Wide tube
• Thin, flexible wall

Question 20

Describe in depth the steps of the circulatory system?

Answer 20

• With each beat, the heart squirts blood into arteries under high pressure. A wave of stretching passes along the artery walls, which you feel as a pulse.
• After stretching, muscle and elastic fibres in the artery walls cause the arteries to contract again. The stretching and contracting of arteries makes the blood flow more smoothly.
• Blood flows under low pressure in veins and so they only need thin walls. As you move, muscles in your skeleton help to push blood along the veins and towards the heart again.

Question 21

What are valves?

Answer 21

Flaps that prevent blood from flowing the wrong way.

Question 22

Why do veins have valves?

Answer 22

In order to make sure blood only flows one way and doesn’t flow the wrong way.

Question 23

What are red blood cells packed with?

Answer 23

Red blood cells are packed with Haemoglobin.

Question 24

How are Erythrocytes adapted to their function?

Answer 24

• They have no nucleus, so there is more space for Haemoglobin.
• The cells are shaped like discs with a dimple on each side which allows a large SA:V ratio for oxygen to diffuse in and out of.

Question 25

What are different types of white blood cells?

Answer 25

1. Lymphocytes 2. Phagocytes

Question 26

What do Lymphocytes do?

Answer 26

Produces antibodies that stick to foreign cells and help to destroy them.

Question 27

What do Phagocytes do?

Answer 27

Surround foreign cells and digests them.

Question 28

What are Platelets?

Answer 28

Tiny fragments of cells that have no nuclei.

Question 29

What do Platelets do?

Answer 29

They produce substances needed to clot the blood at the site of an injury (e.g. when the skin is cut)

Question 30

What is Haemoglobin?

Answer 30

The red, iron-containing pigment found in red blood cells.

Question 31

Label the heart.

Answer 31

Question 32

What do impulses from the nervous system control?

Answer 32

The contraction and relaxation of muscles during each heart beat.

Question 33

What is the heart rate?

Answer 33

The number of times the heart beats in a minute.

Question 34

What is stroke volume?

Answer 34

The volume of blood pushed into the aorta in each beat. It is measured in litres (L).

Question 35

What is the cardiac output?

Answer 35

The volume of blood pushed into the aorta each minute.

Question 36

What is the equation for cardiac output?

Answer 36

Cardiac output (l/min) = Stroke volume (l/beat) x Heart rate (beats/min)

Question 37

How does the cardiac output vary between person to person?

Answer 37

Regular exercise increases the strength of heart muscles and ventricle size. So, fitter people often have bigger stroke volumes, and their hearts can beat more slowly to achieve the same cardiac output as a less fit person.

Question 38

What is cellular respiration?

Answer 38

A series of chemical reactions that release energy from glucose.

Question 39

What type of process is Respiration (Exothermic/Endothermic)?

Answer 39

Respiration is an exothermic reaction (a process in which energy transfer increases the temperature of the surroundings).

Question 40

What is aerobic respiration?

Answer 40

A type of respiration in which oxygen is used to release energy from substances such as Glucose.

Question 41

Where do reactions for the process of aerobic respiration occur?

Answer 41

In the mitochondria of cells.

Question 42

What is the word equation for aerobic respiration?

Answer 42

Glucose + Oxygen --> Carbon Dioxide + Water

Question 43

What does the circulatory system?

Answer 43

- Makes sure that cells have a good supply of oxygen (taken in by the lungs) and Glucose (taken in by the small intestine) - Ensures that wastes are carried away from cells

Question 44

What happens to the rate of aerobic respiration during excersize?

Answer 44

During exercise, the rate of aerobic respiration increases and your muscle cells take more oxygen and glucose from the blood.

Question 45

What happens when oxygen is used up faster than it is replaced?

Answer 45

The amount of anaerobic respiration occurring in the cytoplasm of cells greatly increases.

Question 46

What is anaerobic respiration and what does it produce?

Answer 46

A type of respiration that does not need oxygen. It produces lactic acid (Glucose --> Lactic Acid)

Question 47

How does the amount of energy released from glucose vary between aerobic and anaerobic respiration?

Answer 47

Anaerobic respiration releases less energy from glucose than Aerobic respiration.

Question 48

Why is anaerobic respiration important for animals?

Answer 48

It can release bursts of energy without needing a sudden increase in oxygen supply. This is important for animals that may need to move fast and suddenly, such as when sprinting away from a predator.

Question 49

Why does heart and breathing rates remain high after exercise?

Answer 49

As extra oxygen is needed to replace the oxygen that was lost by blood and muscles. Extra oxygen is also needed to release the extra energy required to get rid of lactic acid.