exchange

Question 1

1

Answer 1

As an organism gets larger its surface area to volume ratio gets smaller.

Question 2

2

Answer 2

The rate of diffusion is equal to: surface area X difference in concentration
Length of diffusion path

Question 3

3

Answer 3

The gas exchange system of insects is comprised of pores called spiracles which connect to tracheae, which divide into tracheoles.

Question 4

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Answer 4

The ends of the tracheoles are filled with water, during anaerobic respiration a build up of lactate in the muscles cells lowers the water potential of the cells and causes this water to leave the tracheoles by osmosis, drawing more air into the tracheoles

Question 5

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Answer 5

The countercurrent exchange principle in fish gills ensures that blood that is already well loaded with oxygen meets water which has its maximum concentration of oxygen, ensuring a concentration gradient is maintained.

Question 6

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Answer 6

Example modifications of a xerophyte include; a thick cuticle, rolling up leaves and stomata in pits or grooves

Question 7

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Answer 7

During inspiration in humans the external intercostal muscles contract and the internal intercostal muscles relax- drawing the rib cage upwards and outwards

Question 8

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Answer 8

In the mammalian alveoli the diffusion pathway for gases is short as the both the alveoli and the blood capillaries are made of a single layer of epithelial cells

Question 9

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Answer 9

Lipids are digested by bile salts emulsifying them into droplets called micelles. They are then hydrolysed by lipases into glycerol and fatty acids.

Question 10

10

Answer 10

Proteins are hydrolysed by a group of enzymes called peptidase: Endopeptidases, Exopeptidases and Dipeptidases

Question 11

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Answer 11

Chylomicrons are specialised particles that contain digested triglycerides, cholesterol and lipoproteins- they transport triglycerides into the blood capillaries via lymphatic capillaries known as lacteals.

Question 12

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Answer 12

In humans a molecule of haemoglobin can carry 4 O2 molecules as it contains four haem groups

Question 13

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Answer 13

In rapidly respiring muscles where the concentration of carbon dioxide is high the oxygen dissociation curve for haemoglobin shifts to the right

Question 14

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Answer 14

Organisms such as llamas and lungworms which live in low oxygen concentrations have an oxygen dissociation curve which is shifted to the left in comparison to human haemoglobin

Question 15

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Answer 15

Mammals have a closed, double circulatory system

Question 16

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Answer 16

During diastole the walls of the atria and ventricles are relaxed and blood enters the atria

Question 17

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Answer 17

During atrial systole blood is forced into the ventricles through the open atrioventricular valves

Question 18

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Answer 18

During ventricular systole the semi lunar vales are open and the atrioventricular valves are closed

Question 19

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Answer 19

Cardiac output = heart rate X stroke volume

Question 20

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Answer 20

Water molecules form hydrogen bonds between then and stick together- this is known as cohesion