EXCRETION

Question 1

What is EXCRETION?

Answer 1

The process of removing waste products from metabolic reactions, toxic materials or excess substance’s from the body

Question 2

Effect of light on the gas waste products of plants?

Answer 2

-during the DAY, there is more LIGHT
-rate of photosynthesis is higher than rate of respiration
-more oxygen is produced than taken in in respiration
-less carbon dioxide is released than used in photosynthesis
-NET EFFECT: oxygen is in excess and is a waste product

-during the NIGHT, there is insufficient LIGHT:
-there is NO photosynthesis, there is ONLY respiration
-ONLY carbon dioxide is produced
-Oxygen is used in respiration and no carbon dioxide is used
-NET EFFECT: carbon dioxide is in excess and is a waste product

Question 3

Water vapour in plants

Answer 3

Majority of water vapour lost is a result of the water drawn up from the transpiration stream.
WATER VAPOUR is excreted through TRANSPIRATION

Question 4

Waste products in plants:

Answer 4

-oxygen
-dioxide
-water vapour
-chemical substances

Question 5

Chemical substances in plants

Answer 5

-plant cells can convert some molecules into chemical substances no longer required by the plant
-when these cannot be converted into a useful substance:
-they are stored in the dying tissue of a plant, where the leaf falls off and the substance is removed

Question 6

Danger of waste products:

Answer 6

1) TOXICITY: if waste products are allowed to build up, they can become toxic at high levels
2)OSMOTIC EFFECT: the waste products can concentrate the blood supply, and therefore draw water out of body cells- which changes their water potential, structure and can impact their function.
3) CARBON DIOXIDE + WATER: carbon dioxide can dissolve in water to form an acidic solution, which lowers the pH of cells. This can impact the reduce the activity of enzymes which is essentially for the key metabolic reactions
4) STORAGE: build up of waste products can take up necessary storage the body requires for more important body cells

Question 7

EXCRETORY ORGANS:

Answer 7

1) the KIDNEY: excretes substances from the urea
2) the SKIN: where excess mineral ions and water are excreted
3) the LUNGS: carbon dioxide and water vapour leaves via the lungs through exhalation.

Question 8

INSPIRATION PROCESS (5)

Answer 8

1) INTERCOSTAL MUSCLES contract, pulling ribs up and out, INCREASING HTE VOLUME of the THORAX
2) diaphragm CONTRACTS and flattens, increasing the volume of the THORAX
3) increased volume, lowers air pressure inside thorax cavity, draws air into the lungs to equalise air pressure

Question 9

EXPIRATION (5)

Answer 9

1) intercostal muscles RELAX, drawing ribs down and in, decreasing volume of the thorax cavity
2) diaphragm RELAX, raising and returning to it’s dome shape, squashing and decreasing volume of the THORAW
3) decreased volume raises air pressure, forcing air out of the lungs

Question 10

ADAPTATIONS of the ALVEOLI:

Answer 10

1) ROUNDED SAC SHAPE + MANY ALVEOLI: increase the SA:V ratio, maximising diffusion
2)GOOD BLOOD SUPPLY: maintains a steep concentration gradient
3) VENTILATION: maintains a steep concentration gradient
4) thin one-cell thick walls: thin alveolus walls + capillaries shorten diffusion distance

Question 11

SMOKING harmful effects:

Answer 11

NICOTINE:
-raises blood pressure which increases risk of blood clotting + heart attack

CARBON MONOXIDE:
-reduces the capacity of the blodo to carry oxygen
-which puts more pressure on breathing + circulatory system
-increased risk of CHD

TAR:
-causes mucus build up which can lead to infections and damage cilia
-which is called chronic bronchitis