The variety of life (heam & starch)

Question 1

The oxygen dissociation curve of the fetus is to the left of that for its mother. Explain
the advantage of this for the fetus.

Answer 1

1. Higher affinity for oxygen;
2. At lhigh partial pressure
3. Oxygen moves from mother/to fetus;

Question 2

After birth, fetal haemoglobin is replaced with adult haemoglobin. Use the graph to
suggest the advantage of this to the baby

Answer 2

1. Low affinity / oxygen dissociates;
2. (Oxygen) to respiring
   tissues/muscles/cells;

Question 3

Explain the advantage to the lugworm of having haemoglobin with a dissociation curve in the position shown.

Answer 3

High(er) affinity for oxygen

At lower partial pressure

Question 4

In humans, substances move out of the capillaries to form tissue fluid. Describe how this tissue fluid is returned to the circulatory system.

Answer 4

1. pressure lower in capillary
2. Water returns;
3. By osmosis;
4. Water potential lower in capillary
5. Due to protein in blood;
6. Returns via lymph system

Question 5

Give features of starch and explain how they enable it to act as a storage substance.

Answer 5

1. Helical/coiled; Compact - ‘tightly packed’
2. Insoluble; does not affect water potential so prevents osmosis
3. Large molecule; so Does not leave cell

Question 6

Explain how the structure of cellulose is related to its role in plant cell walls.

Answer 6

Long unbranched chains (of glucose);
Joined by hydrogen bonds form fibrils
which provide structural support;

Question 7

describe how haemoglobin loads and unloads oxygen in the body.

Answer 7

hb associates oxygen at high p.O 2
in lungs haemoglobin has a high affinity for oxygen;
dissociates oxygen at low p.O2
dissociation is due to higher carbon dioxide concentration;

Question 8

Heat from respiration helps mammals to maintain a constant body temperature.
Explain the relationship between the SURFACE AREA to VOLUME ratio of mammals and the oxygen dissociation curves of their haemoglobins.

Answer 8

1. Smaller mammals have greater SA:VOL
2. So more heat lost
3. Smaller mammal also has greater rate of metabolism;
4. Oxygen is required for respiration;
5. haemoglobin has a lower affinity in smaller mammels so oxygen is released more readily

Question 9

Name the process in which cells become adapted for different functions.

Answer 9

differentiation

Question 10

Describe and explain how an increase in respiration in the tissues of a mammal affects the oxygen dissociation curve of haemoglobin.

Answer 10

Increase in carbon dioxide
this reduces the pH
which moves the curve to the right

Question 11

There is less oxygen at high altitudes, why is it an advantage for people who live there to have a lot of red blood cells

Answer 11

More haemoglobin;

So can load more oxygen

Question 12

Explain the advantage to people living at high altitude of having the oxygen dissociation curve shifted to the right

Answer 12

Haemoglobin has lower affinity for oxygen

therefore more oxygen is released into the cells

Question 13

Explain how cellulose gives plant cells strength

Answer 13

unbranched chains; lie side by side to form microfibrils; which form Hydrogen bonds between chains holding them together; this gives structural support
3

Question 14

what is the monomer in cellulose?

Answer 14

beta glucose

Question 15

Name the type of reaction that converts cellulose to its monomers

Answer 15

hydrolysis

Question 16

Describe the function of the chlorplast

Answer 16

the site of Photosynthesis;

Uses light energy to produce carbohydrates

Question 17

Explain what is meant by a quaternary structure.

Answer 17

A protein with more than 1 polypeptide chains

Question 18

Explain why haemoglobin is 96 % saturated with oxygen when it leaves the lungs

Answer 18

PO2 is high in the lungs and there is a low concentration of CO2 in the lungs

Question 19

Explain how carbon dioxide helps haemoglobin to release oxygen to rapidly respiring tissues.

Answer 19

Displaces dissociation curve to the right as Hb has a lower affinity for oxygen due to high concentration of CO2

Question 20

Explain why there is a high concentration of carbon dioxide in rapidly respiring tissue.

Answer 20

Carbon dioxide is a product of respiration;

Question 21

describe the test for starch

Answer 21

substance turns blue-black with iodine

Question 22

What is meant by the term partial pressure?

Answer 22

It is a measure of the concentration of a gas

Question 23

Explain how exercise can effect:

• the temperature
• the pH
• the PO2 and PCO2

Answer 23

1. muscle contraction causes increased respiration; 2.increased CO2 production lowering blood pH;
2. lactate released lowering blood pH;
3. increased heat released therefore increased temperature;
4. increased O2 consumption lowering tissue PO2

Question 24

Explain why the oxygen dissociation graph is shifted to the right during exercise (Bohr effect)

Answer 24

haemoglobin has a lower affinity for oxygen; due to increased CO2 production so more O2 is released for respiration;

Question 25

The oxygen dissociation curve for haemoglobin shifts to the right during vigorous
exercise. Explain the advantage of this shift.

Answer 25

1. Lower affinity for oxygen therefore unloads more oxygen more readily;
2. To muscles cells;
3. For high respiration;

Question 26

Explain how the body shape of an animalcould be adaptation to living in a cold environment.

Answer 26

small SA:VOL therefore reduced heat loss

Question 27

How are cellulose and starch different

Answer 27

Starch
1. 1,4 and 1,6 bonds - branched
2. All monomers same way up
3. Helix,coiled,compact
4. Alpha glucose
5. No micro/macro fibrils
  Cellulose
1. 1,4 bonds but no 1,6 bonds - unbranched 
2. Alternate monomers upside down;
3. Straight;
4. Beta glucose;
5. Has Micro/macro fibrils

Question 28

How is the structure of cellulose linked to its function

Answer 28

1. H-bonds / micro/macro fibrils /fibres;

2. Strength / rigidity / inelasticity;

Question 29

What is the advantage to the organism if their Hb has a higher affinity for oxygen at low pO2?

Answer 29

1. Hb will become more saturated with O2 even with low O2 concentration
2. so can act as an oxygen store

Question 30

Explain why fetal Hb has a higher affinity for O2 than adult Hb

Answer 30

1. fetal Hb needs to load oxygen
2. from maternal Hb
3. across the placenta

Question 31

Describe two adaptations that enable oxygen to be transported rapidly from maternal blood into
the fetal tissues

Answer 31

1. reduction of tissue layers in placenta

2. increase in maternal blood supply to placenta giving larger exchange surface area;

Question 32

Why is fetal haemoglobin unsuitable for use after birth?

Answer 32

1. has greater affinity for oxygen than adult haemoglobin;
2. higher oxygen tensions in atmosphere than placenta;
3. thus in air would be unable to unload oxygen to tissues;