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all3 Flashcards

(50 cards)

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1
Q

Explain the relationship between the number of leaves removed from the plant shoot and the mean rate of water uptake.

A

As number of leaves are reduced

  1. Less surface area;
  2. Fewer stomata;
  3. Less evaporation/transpiration;
  4. Less cohesion/tension/pulling (force);
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2
Q

A mutation in the gene coding for enzyme B could lead to the production of a non-functional enzyme. Explain how.

A
  1. Change in base sequence (of DNA/gene);
  2. Change in amino acid sequence / primary structure (of enzyme);
  3. Change in hydrogen/ionic/ disulphide bonds;
  4. Change in the tertiary structure/active site (of enzyme);
  5. Substrate not complementary/cannot bind (to enzyme / active site) / no enzyme-substrate complexes form;
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3
Q

Using isoniazid to treat diseases caused by other species of bacteria could increase the chance of the bacterium that causes tuberculosis becoming resistant to isoniazid. Use your knowledge of gene transmission to explain how.

A
  1. Resistance gene/allele;
  2. On plasmid;
  3. (Spread by) horizontal transmission;
  4. (Involves) conjugation/pilus;
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4
Q

ethical argument for maintaining biodiversity.

A

(We should maintain biodiversity to)
Prevent extinction /loss of populations/ reduction in populations /loss of habitats / save organisms for future generations (idea of);

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5
Q

economic argument for maintaining biodiversity

A

A suitable example of how some species may be important financially e.g.

  1. medical / pharmaceutical uses;
  2. commercial products / example given;
  3. tourism;
  4. agriculture;
  5. saving local forest communities;
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6
Q

the relationship between the percentage of original forest area remaining and the percentage of bird species that have become extinct

A
  1. Fewer plant species / decrease in plant diversity;
  2. Fewer habitats/nesting sites;
  3. Fewer niches;
  4. Fewer food sources/varieties;
  5. Less protection from p
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7
Q

Explain how a larger body size is an adaptation to a colder climate.

A
  1. have) a low(er) SA:VOL;

2. (So) less heat loss / more heat retained;

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8
Q

Describe how DNA is replicated.

A
  1. Strands separate / H-bonds break;
  2. DNA helicase (involved);
  3. Both strands/each strand act(s) as (a) template(s);
  4. (Free) nucleotides attach;
  5. Complementary/specific base pairing / AT and GC;
  6. DNA polymerase joins nucleotides (on new strand);
  7. H-bonds reform;
  8. Semi-conservative replication / new DNA molecules contain one old strand and one new strand;
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9
Q

how the doctor could have recognised which cells were in interphase when looking at the tissue samples

A
  1. No visible chromosomes/chromatids;

2. Visible nucleus;

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10
Q

way the scientists could have allocated the patients to each group

A
  1. Random;
  2. Method e.g. number generator / number out of a hat; OR
  3. Matched / all the same;
  4. For e.g. age / sex;
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11
Q

Why measurements are repeated several times

A
  1. (Allows) anomalies to be identified/ ignored/ effect of anomalies to be reduced / effect of variation in data to be minimised / concordant results;
  2. (Makes) average/mean (more) reliable;
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12
Q

Structures found in prokaryotic cells but not in eukaryotic cells.

A
  • Capsule / glycocalyx / slime layer
  • Circular / ring of / non-linear DNA / DNA without histones
  • Plasmid
  • Flagellum
  • Pilus
  • Small / less dense / 70s ribosomes
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13
Q

How the increased secretion of chloride ions causes diarrhoea.

A
  • lower/more negative water potential in gut

- means water leaves body cells by osmosis

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14
Q

Why must boiled water be used to make an ORS?

A

-kills bacteria

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15
Q

The type of bond that joins amino acids together in a polypeptide

A

-peptide

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16
Q

Why there are lots of mitochondria in a cell

A
  • it is the site of aerobic respiration
  • they releases ATP/energy
  • for active transport/ transport against the concentration gradient / protein synthesis / exocytosis
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17
Q

Cell fractionation- why the scientists homogenised the tissue

A

-breaks open cells and releases cell contents

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18
Q

Cell fractionation- why the scientists filtered the resulting suspension

A

-removes complete cells

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19
Q

Cell fractionation- why the scientists kept the suspension ice cold during the process

A

-reduces enzyme activity

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20
Q

Cell fractionation- why the scientists used isotonic solution during the process

A
  • prevents osmosis so there is no movement of water

- so organelles not damaged

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21
Q

What is an antigen

Study These Flashcards
A

-a protein that causes an immune response

22
Q

Importance of memory cells

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A
  • memory cells remain from previous infection
  • when an individual comes in contact with the antigen again
  • a rapid secondary response is caused and many antibodies are produced
  • which destroy the antigen before it can cause harm/symptoms
23
Q

Advantage of vaccinating young men as well as young women against a STD (HPV) that can cause cervical cancer

Study These Flashcards
A
  • HPV is destroyed in males so they can’t be carriers

- and pass it on to other unvaccinated females

24
Q

Enzyme specificity- why the enzyme only breaks down a specific lipid

Study These Flashcards
A
  • the active site
  • has a complimentary and specific shape
  • so does not bind with other lipids
  • to form e-s complexes
25
Suggest why they cannot give the missing enzyme as a tablet that is swallowed
-enzymes are proteins -and are digested by enzymes OR -enzymes are too large -to enter the blood stream
26
Risk factors associated with coronary heart disease
(cigarette) smoking / high blood pressure / gender / age / alcohol / genes / lack of exercise / obesity / stress / high blood cholesterol
27
Explain why they divided them randomly (groups)
-avoid bias
28
Importance of control groups
-to ensure the results are not due to another factor
29
Why an increase in the diameter of the lumen of the main artery in the arm is associated with a reduced risk of coronary heart disease
- coronary artery also likely to have a wide lumen - so less chance of high blood pressure - so less chance of blood clot/thrombosis - so less chance of atheroma
30
How substances can cross a cell surface membrane
-(Simple / facilitated) diffusion from high to low concentration / down concentration gradient; -Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer OR -Large / polar / water-soluble molecules go through proteins -Water moves by osmosis / from high water potential to low water potential / from less to more negative water potential -Active transport is movement from low to high concentration / against concentration gradient -Active transport / facilitated diffusion involves proteins / carriers - Active transport requires energy / ATP -Ref. to Na+ / glucose co-transport
31
Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them.
1 Many alveoli / alveoli walls folded provide a large surface area 2 Many capillaries provide a large surface area; 3 (So) fast diffusion 4 Alveoli or capillary walls / epithelium / lining are thin / short distance between alveoli and blood 5 Flattened / squamous epithelium 6 (So) short diffusion distance / pathway 7 (So) fast diffusion 8 Ventilation / circulation 9 Maintains a diffusion / concentration gradient 10 (So) fast diffusion
32
Type of reaction catalysed by the enzyme lactase
-hydrolysis
33
Reducing sugar test
- add Benedict’s reagent and heat | - for a positive result it will have a red/orange/yellow/green colour
34
Competitive inhibition- why a high concentration of galactose slows down the breakdown of lactose by lactase
- galactose is a similar shape to lactose, so are both complimentary to the active site - galactose therefore fits into the active site of the enzyme - this prevents the substrate binding with the active site so less e-s complexes are made
35
Why lactose intolerant people (cant produce enzyme lactase) get diarrhoea when they drink milk containing lactase
- decreased water potential in gut | - means water enters gut by osmosis
36
Effect of temperature on reaction- graph explanation (high temp)
- the enzyme becomes denatured as hydrogen bonds holding the tertiary structure are broken - meaning there is a change in the active site of the enzyme - so the substrate no longer fits into the active site and fewer e-s complexes are formed - more enzyme molecules are denatured as temperature increased
37
How the students make sure pH doesn’t change
Use a buffer
38
Why emphysema reduces the efficiency of gas exchange in the lungs
1. Alveoli break down / collapse / rupture / fewer alveoli / larger alveoli or alveolar wall/epithelium walls thicken; 2. Reduced surface area / increased diffusion pathway; 3. (So) less diffusion; 4. Less elastin / elastic (tissue) / not recoiling / loss of elasticity / elastin permanently stretched; 5. Reduced flow rate / less air expelled; 6. So small / reduced diffusion or concentration gradient;
39
Differences between active transport and facilitated diffusion
Active transport: - uses energy/ATP - is against concentration gradient / low to high concentration - does not use channel proteins / only uses carrier proteins
40
Why a control group is used
-to see the effect of the drug
41
How the control group is treated
- using a placebo | - otherwise the same
42
What causes the maximum pressure in the atrium to be much higher than in the atrium
- the ventricle has more muscle | - so contractions are stronger
43
How atheroma can lead to a heart attack
- coronary artery is blocked - which restricts oxygen supply to the heart muscle - and prevents respiration/ATP production, so heart muscle dies
44
How a phagocytic white blood cell destroys bacteria
- phagocyte recognises antigens on the bacteria as foreign and is attracted to the bacteria by chemicals - it then engulfs the bacteria - so the bacteria is in a vesicle - then the lysosome fuses with the vesicle - and bacteria is hydrolysed by enzymes
45
How the epithelial cells that line the small intestine are adapted for the absorption of glucose
- they have microvilli - which increase surface area - many mitochondria - produce ATP in respiration for active transport - Carrier proteins for active transport; - Channel / carrier proteins for facilitated diffusion - Co-transport of sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose; - Membrane-bound enzymes digest disaccharides / produce glucose
46
Structure in a eukaryotic cell- diagram
- nucleus - Mitochondrion - Endoplasmic reticulum/ER - Lysosome
47
Functions of mitochondria
-aerobic respiration to produce ATP/provide energy
48
Advantages of a transmission electron microscope
- better resolution - Shorter wavelength - To see internal structures/ organelles
49
Air moves into the lungs between times P and Q. Explain how the diaphragm causes this.
- Diaphragm contracts/moves down/ flattens - Increases volume (of thorax) - Decrease in pressure - Air moves from high to lower pressure/down
50
Describe how oxygen in air in the alveoli enters the blood in capillaries.
- Diffusion | - Across alveoli epithelium/ capillary endothelium
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