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Question 1

Describe the pressure changes during Inhalation

Answer 1

expanding the rib cage/pulling on the outer pleural membrane will lower the pressure in the pleural cavity and the inner pleural membrane pulls on the lungs

Question 2

Why is countercurrent flow affective?

Answer 2

a constant concentration gradient is maintained across the entire gill and more oxygen is absorbed as the equilibrium is never reached.

Question 3

What happens to the pressure in the left side of the heart after ventricular systole?

Answer 3

pressure drops when the left ventricle relaxes but pressure in the aorta does not fall to zero because of the closing of the aortic/semi lunar valve to prevent the backflow of blood

Question 4

What is a closed circulatory system?

Answer 4

blood is only carried in the blood vessels and substances are only carried to and from other cells and tissues

Question 5

What does the P wave represent?

Answer 5

where an electrical impulse is generated by the SAN causing the depolarisation and then contraction of the atria (atrial systole)

Question 6

Describe the pressure in the atrium

Answer 6

there is a lower pressure in the atrium as it pushes blood into the ventricle which is really close

Question 7

What does the QRS complex respresent?

Answer 7

where the AVN passes on the wave of excitation to the bundle of His and purkinje fibres so causes depolarisation of the ventricles where ventricular walls contract in ventricular systole

Question 8

What does the T wave represent?

Answer 8

he T wave is the repolarisation of the ventricles which causes ventricular diastole where the ventricles relax

Question 9

What happens to the heartbeat during exercise?

Answer 9

there is less time between atrial systole and ventricular systole so the distance between the consecutive P waves would be smaller

Question 10

Why might partial pressure of oxygen drop?

Answer 10

partial pressure of oxygen may fall to 3.0 kPa in muscle tissues during vigorous exercise and high levels of aerobic respiration as the muscles use more oxygen

Question 11

What do the H+ ions do in oxygen dissociation?

Answer 11

the hydrogen ions dissociate oxyhaemoglobin to release oxygen so it can be used in respiration by muscles

Question 12

What do Cl ions do in the oxygen dissociation?

Answer 12

chlorine ions enter in the chloride shift to maintain the electrochemical neutrality

Question 13

What happens to organisms living at a high altitude?

Answer 13

at low levels of oxygen, the organism’s haemoglobin has a higher affinity for oxygen so it absorbs more oxygen and it will dissociate from it slowly

Question 14

Why is there lower mean pressure in the lung capillary?

Answer 14

so their flow rate is reduced meaning there is more time for gas exchange and less tissue fluid is produced

Question 15

What is the difference in function between an axon and a dendrite?

Answer 15

a dendrite conducts an impulse towards the cell body and an axon conducts the impluse away from the cell body.

Question 16

What happens at resting potential?

Answer 16

the membrane is relatively impermeable to sodium as the Na+ channels are shut. The Na+/K+ pump uses ATP to actively maintain the resting potential.

Question 17

What would happen to oxygen consumption on a demyelinated neurone?

Answer 17

the rate would increase because of more aerobic respiration happening to produce more ATP as more pumps have to work across the whole length of the membrane as saltatory conduction does not occur.

Question 18

How does a larger diameter affect the neurone?

Answer 18

this means less resistance so the ions can flow faster

Question 19

Why is removing excess fluid during dialysis important?

Answer 19

So body fluids don’t become too dilute and entry of water can cause cells to burst

Question 20

How does high blood pressure cause swelling of some tissues?

Answer 20

Increases hydrostatic pressure so more tissue fluid is formed (excess can’t be reabsorbed) so fluid accumulates in tissues

Question 21

How do capillaries increase rate of selective reabsorption?

Answer 21

Thin walls - short diffusion path
maintain a conc. gradient

Question 22

Describe pressure changes in afferent and efferent arteriole

Answer 22

Muscles in the walls of the afferent arteriole relaxes and contract in the efferent arteriole

Question 23

Define heterotrophic organism

Answer 23

An organism that requires a source of organic molecules for their nutrition

Question 24

Describe the process of saprotrophic nutrition (in fungi)

Answer 24

• secretion of enzymes (from hyphae)
• extracellular digestion of dead organic matter
• absorption of soluble molecules

Question 25

Describe two differences between amoeba and hydra digestion

Answer 25

- amoeba has intracellular enzymes but hydra has extracelular - amoeba engulfs food using membrane but hydra captures it with tentacles

Question 26

Define mechanical digestion

Answer 26

digestion that breaks down food into smaller pieces to increase its total surface area

Question 27

Define chemical digestion

Answer 27

digestion that involves hydrolysis/use of enzymes to break larger molecules into smaller insoluble molecules

Question 28

Why are hydrogen carbonate ions (HCO3-) important in the small intestine?

Answer 28

- they help neutralise the stomach acid - also help to provide optimum pH for enzyme activity

Question 29

Define the term holozoic

Answer 29

Internal digestion of food/internal digestive system

Question 30

Define the term saprotrophic

Answer 30

External digestion of food by secretion of enzymes onto food (extracellular digestion)

Question 31

Define the term photoautotrophic

Answer 31

Formation of organic molecules from inorganic molecules using light energy

Question 32

How is optimum pH maintained in the duodenum?

Answer 32

alkaline secretion from the Brunner's glands will neutralise the acid from the stomach

Question 33

Why is Starch an effective storage molecule?

Answer 33

- it is compact so it can fit a large amount in a small space - it is insoluble

Question 34

One advantage of capillaries being narrow

Answer 34

This can increase the surface area of the capillary walls so gas exchange is more efficient

Question 35

How does movement by the ribcage cause an increase in lung volume?

Answer 35

The inner pleural membrane moves outwards and this pulls on the surface of the lungs and causes the alveoli to expand

Question 36

Why is a higher body temp an advantage in nerve conduction?

Answer 36

- leads to a faster rate of diffusion - so action potential is reached much faster

Question 37

What guidelines should you follow when drawing biological diagrams?

Answer 37

- don't cross the labels and don't shade - add a magnification or scale bar

Question 38

What type of nervous system do Cnidaria have?

Answer 38

A nerve nert

Question 39

How does H+ ions secreted by tapeworms affect its host?

Answer 39

- it denatures the carrier protein shape, so the food molecules don't fit - so less product is absorbed

Question 40

How do H+ ions affect the O2 conc. in the blood?

Answer 40

- increased H+ decreases the affinity of haemoglobin for O2 - so more dissociates and is released