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Topic 3 terminologies > Marck Scheme Answers > Flashcards

Marck Scheme Answers Flashcards

1
Q

What is the difference between active and passive immunity? (1)

A

Active immunity is slower

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2
Q

Why is a mixture of venoms from several snakes of the same species used to make an antivenom? (1)

A

There may be a different form of antigen/toxin within one species

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3
Q

Why is an animal observed when injected with a newly tested antivenom/antibody (1)

A

To ensure that the animal does not suffer from the venom/vaccine

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4
Q

What are B-cells and how are they produced? (1)

A

B-cells are specific to venom/antigens and are produced by mitosis

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5
Q

Describe the gross structure of the human gas exchange system and how we breathe in and out (5)

A

• Trachea, bronchi, bronchioles, alveoli
Breathing in
• Diaphragm contracts and external intercostal muscles contract
• Volume increases and pressure decreases in the thoracic cavity
Breathing out
• Volume decreases and pressure increases in the thoracic cavity
• Diaphragm relaxes and internal intercostal muscles contract

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6
Q

Describe and explain the effect of increasing carbon dioxide concentration on the dissociation of oxyhemoglobin (2)

A

• Increases/more oxygen dissociation/unloading
• By decreasing the blood (pH)

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7
Q

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels (7)

A
  • Micelles contain salts and fatty acids/monoglycerides
  • Make fatty acids/monoglycerides (more) soluble (in water)
  • Bring/release/carry fatty acids/monoglycerides to cell/lining (of the ileum)
  • Maintain higher concentration of fatty acids/monoglycerides to cell/lining (of the ileum)
  • Fatty acids/monoglycerides absorbed by diffusion
  • Triglycerides reformed in cells
  • Vesicles move to cell membrane
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8
Q

Explain how an arteriole can reduce the blood flow into capillaries (2)

A
  • Muscle contracts
  • Narrow lumen reduces blood flow
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9
Q

Suggest and explain why the combined actions of Endopeptidases and Exopeptidases are more efficient than exopeptidases on their own (3)

A

• Endopeptidases hydrolyse internal peptide bonds
• Exopeptidases remove amino acids/hydrolyse (bonds) at end
• More ends or increase in surface area (for absorption)

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10
Q

Explain why the addition of a respiratory inhibitor stops the absorption of amino acids (4)

A

• No/less ATP produced
• Sodium (ions) not moved (into/out of cell)
• No diffusion gradient for sodium (to move into cell with amino acid)
• No concentration gradient for sodium (to move into cell with amino acid)

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11
Q

Name the process by which oxygen reaches the cells inside the body of small, thin animals (1)

A

SIMPLE diffusion

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12
Q

Suggest why means are used in investigations (3)

A

• For comparison
• To see effect of variables
• Takes into account outliers/anomalous results

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13
Q

One of the severe disabilities that results from emphysema is that walking upstairs becomes difficult.

Explain how a low FEV1 (the volume of air a person can breathe out in one second) value can cause this disability (4)

A

• Less carbon dioxide removed
• Less oxygen uptake in the blood
• Less aerobic respiration/ATP
• More anaerobic respiration

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14
Q

Some people produce a much higher ventricular blood pressure than normal. This can cause tissue fluid to build up outside the blood capillaries of these people.

Explain why (3)

A

• More fluid forced/filtered out of the capillary/blood due to high pressure
• Less return of fluid (into capillary/blood) due to pressure
• Lymphatic system cannot drain away all excess fluid

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15
Q

Some drugs used to reduce high ventricular blood pressure cause widening of blood vessels.

Suggest how widening of blood vessels can reduce ventricular blood pressure (3)

A

• Larger lumen/volume of blood vessels
• Reduces blood pressure in the blood vessels
• Less friction/ resistance in the blood vessels

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16
Q

Use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared to a horse (3)

A

• Mouse is smaller so it has a larger surface area to volume ratio
• More/faster heat loss
• Faster rate of heat loss/ metabolism

17
Q

Give two ways in which the structure of starch is different from cellulose (4)

A
  • Starch contains alpha glucose
  • Starch is helical and not straight
  • Starch contain 1,6 branching
  • Has no microfibrils
18
Q

Suggest one way in which sieve tubes are adapted for mass transport (Application and knowledge) (2)

A

• No/few organelles/very little cytoplasm/ more room/large vacuole/thick walls
• So easier/more flow to resist pressure

19
Q

Describe how a high pressure is produced in the leaves (Application) (3)

A

• Water potential becomes lower as sugar enters the phloem
• Water enters the phloem by osmosis
• Increased volume of water causes increased pressure

20
Q

What is the difference between active transport and facilitated diffusion in terms of proteins (knowledge)(1)

A

• Facilitated diffusion involves channel or carrier proteins whereas active transport only involves carrier proteins

21
Q

Describe how you would use a microscope to find the mean diameter of triglyceride droplets on a slide (6)

A
  • measure the eyepiece graticule/ scale
  • Calibrate the stage micrometer/ object of known size
  • Repeats and calculate the mean/
  • Use a ruler to estimate the field diameter under the microscope
  • How many droplets go across the field
  • Repeats and calculate the mean
22
Q

Describe the action of lipase and bile salts on the hydrolysis of triglycerides (3)

A
  • Small droplets have a larger surface area to volume ratio
  • More surface for lipase to act on leading to faster digestion of triglycerides
  • Fatty acids are produced more quickly so pH will drop more quickly with bile salts
23
Q

In healthy lungs, a gradient is maintained between the concentration of oxygen in the
alveoli and the concentration of oxygen in the lung capillaries.
(i) Describe how ventilation helps to maintain this difference in oxygen concentration (2)

A

(In alveolus)
- Need the idea of air moving and oxygen concentration
- Brings in air containing a high(er) oxygen concentration;
Neutral: reference to carbon dioxide concentration
Removes air with a low(er) oxygen concentration

24
Q

(ii) Give one other way that helps to maintain the difference in oxygen concentration. (1)

A

(ii) Circulation of blood / moving blood;

25
Q

How is Haemoglobin formed? (1)

A

Via condensation reactions

26
Q

Hereditary persistence of fetal haemoglobin (HPFH) is a condition in which production of
fetal haemoglobin continues into adulthood. Adult haemoglobin is also produced.
People with HPFH do not usually show symptoms. Suggest why. (2)

A
  • Enough adult Hb produced / enough oxygen released / idea that curves / affinities /
  • Hb are similar / more red blood cells produced;
27
Q

The hydrostatic pressure falls from the arteriole end of the capillary to the venule end of
the capillary. Explain why. (1)

A

Loss of water / loss of fluid / friction (against capillary lining)

28
Q

High blood pressure leads to an accumulation of tissue fluid. Explain how. (3)

A
  • High blood pressure = high hydrostatic pressure;
  • Increases outward pressure from (arterial) end of capillary / reduces inward
    pressure at (venule) end of capillary;
  • (So) more tissue fluid formed / less tissue fluid is reabsorbed.
29
Q

The water potential of the blood plasma is more negative at the venule end of the capillary
than at the arteriole end of the capillary. Explain why. (3)

A
  • Water has left the capillary;
  • Proteins (in blood) too large to leave capillary;
  • Increasing / giving higher concentration of blood proteins (and thus wp)
30
Q

Describe the mass flow hypothesis for the mechanism of translocation in plants (4 marks)

A
  • In source/leaf sugars actively transported into phloem
  • By companion cells
  • Lowers water potential of sieve cell/tube and water enters by osmosis
  • Increase in pressure causes mass movement (towards sink/root)
  • Sugars used/converted in root for respiration for storage
31
Q

explain why the diameter of the branch decreased during the first 12 hours (1)

A

increase transpiration) produce a higher tension / reduces the pressure in the xylem reducing the diameter / adhesive forces between xylem and water;

32
Q

How does oxygen diffuse into the capillaries (1)

A

-Down the diffusion gradient

33
Q

Control variables

A
  • Concentration of…
  • Volume of……
  • Temperature
34
Q

Mammals have some cells that produce extracellular proteases. They also have
cells with membrane-bound dipeptidases.
Describe the action of these membrane-bound dipeptidases and explain their
importance (2)

A
  1. Hydrolyse (peptide bonds) to release amino
    acids;
  2. Amino acids can cross (cell) membrane;
    OR
    Dipeptides cannot cross (cell) membrane;
    OR
    Maintain concentration gradient of amino acids
    for absorption;
    OR
    Ensure (nearly) maximum yield from protein
    breakdown;
35
Q

At Q on Figure 3 there is a small increase in pressure and in rate of blood flow in the
aorta.
Explain how this happens and its importance. (2)

A
  1. Elastic recoil (of the aorta wall/tissue);
  2. Smooths the blood flow
    OR
    Maintains rate of blood flow
    OR
    Maintains blood pressure
36
Q

A different student did this investigation. He did not have a colorimeter.
Describe a method this student could use to prepare colour standards and use them
to give data for the total anthocyanin extracted. (3)

A
  1. Use known concentration of blueberry
    juice/extract
    OR
    Use known concentration of
    anthocyanin/pigment (solution)
    OR
    Use known concentration of (extraction) solvent
    to be added to blueberries;
  2. Prepare dilution series;
  3. Compare (results) with colour standards to give
    score/value/concentration;
37
Q

Particulate matter is solid particles and liquid particles suspended in air. Polluted air
contains more particulate matter than clean air.
A high concentration of particulate matter results in the death of some
alveolar epithelium cells. If alveolar epithelium cells die inside the human body they
are replaced by non-specialised, thickened tissue.
Explain why death of alveolar epithelium cells reduces gas exchange in human lungs.
[3 marks]

A
  1. Reduced surface area;
  2. Increased distance for diffusion;
  3. Reduced rate of gas exchange;

Topic 3 terminologies (6 decks)

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