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1
Q

Why do people that can’t digest lactose get diarrhoea when they drink milk? (water potential)

A
  • there is a lower water potential in the gut

- so water leaves cells by osmosis

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2
Q

What is the reaction catalysed by the enzyme lactase?

A

(Lactose +) Water ->(Glucose +) Galactose

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3
Q

Name the type of chemical reaction shown in this equation.

(Lactose +) Water ->(Glucose +) Galactose

A

Hydrolysis

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4
Q

Protein test- lactase from lactose solution

A
  • Add Biuret reagent to both solutions
  • lactase (enzyme) will give purple
  • lactose (reducing sugar) will remain blue
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5
Q

The path by which oxygen goes from an alveolus to the blood

A
  • through the epithelium

- through the capillary epithelium

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6
Q

how ventilation helps to maintain this difference in oxygen concentration

A
  • brings in air containing a higher oxygen concentration

- Removes air with a lower oxygen concentration

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7
Q

way that helps to maintain the difference in oxygen concentration

A

-circulation of blood

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8
Q

how the drug lowers the rate of reaction- competitive inhibitor

A
  • the drug is a similar shape to the substrate
  • so it fits the active site as it is a complimentary shape
  • so less substrate binds to form enzyme-substrate complexes
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9
Q

Methotrexate only affects the rate of the reaction controlled by folate reductase. Explain why this drug does not affect other enzymes

A

-the drug is a similar shape to the substrate so only fits into that particular active site

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10
Q

How mitochondrion help the cell to absorb the products of digestion

A
  • it is the site of aerobic respiration where ATP is produced/energy is released
  • for active transport
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11
Q

why they have low concentrations of amino acids in their blood if less microvilli

A
  • reduced surface area= less absorption

- membrane bound enzymes are less effective so proteins are not digested

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12
Q

How they could improve the reliability of their results by taking additional readings

A
  • anomalies can be identified

- and mean could be calculated

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13
Q

How they could improve their graph by taking additional readings

A
  • line of best fit is more precise

- so point where line crosses is more precise

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14
Q

Types of pathogen

A
  • virus
  • fungus
  • bacteria
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15
Q

ways in which a pathogen may cause disease when it has entered the body

A
  • produces toxins

- damages cells

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16
Q

why antibodies are referred to as monoclonal

A

-antibodies are produced from the same plasma cell

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17
Q

Protein structure- why are tests using monoclonal antibodies specific

A
  • the specific primary structure leads to a specific tertiary structure
  • which is only complimentary to one antigen
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18
Q

The cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular node (AVN). Describe how

A
  • the SAM initiates heart beat (acting like a pace maker)
  • and sends impulses across atria causing atria contraction
  • AVN delays impulses
  • allowing ventricles to fill before they contract
  • then AVN sends impulses down Bundle of His / Purkyne fibres
  • causing ventricles to contract from base up
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19
Q

What is atheroma and how may it cause myocardial infarction?

A
  • atheroma is fatty material
  • in the artery wall
  • and it is linked to blood clot/thrombosis
  • where it can block the coronary artery
  • which reduces oxygen/glucose supply to the heart muscle
  • which dies as it can no longer respire
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20
Q

Why hydrogen bonds are important in cellulose molecules

A
  1. Holds chains/cellulose molecules together/forms cross links between chains/cellulose molecules/forms microfibrils;
  2. Providing strength/rigidity (to cellulose/cell wall);
  3. Hydrogen bonds strong in large numbers;
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21
Q 
A starch molecule has a spiral shape. Explain why this shape is important to its
function in cells.
Study These Flashcards
A

-Compact/occupies small space/tightly packed;

22
Q

What is the evidence from the diagram that haemoglobin has a quaternary structure?

Study These Flashcards
A

-More than one polypeptide/chain;

23
Q

How the haemoglobin in one organism may have a different chemical structure from the haemoglobin in another organism

Study These Flashcards
A

-Different primary structure/amino acids/different number of polypeptide chains;

24
Q

what is meant by a phylogenetic relationship

Study These Flashcards
A

-Shows evolutionary relationship;

25
They made samples of hybrid DNA using a gene that was found in all three species. Explain why it was important that they made samples of hybrid DNA from the same gene.
1. Base sequence will be similar/some bases in common; | 2. These bases will bind together/hydrogen bonds/complementary pairs;
26
Explain what caused the DNA to separate at a higher temperature.
1. Relationship is closer/more complementary bases/more base pairs; 2. More hydrogen bonds; 3. More heat energy needed (to separate bonds);
27
Banana growers can only grow new variety B plants from suckers. Suckers grow from cells at the base of the stem of the parent plant. Use your knowledge of cell division to explain how growing variety B on a large scale will affect the genetic diversity of bananas
- Low genetic diversity because they are produced by mitosis; - Will all have the same DNA/genes/alleles/ will be genetically identical/will be clones; OR - Low genetic diversity because they are not produced by meiosis; - No crossing over/independent segregation/will not be genetically different;
28
Farmers clear tropical forest and grow crops instead. Explain how this causes the diversity of insects in the area to decrease.
1. Lower diversity of plants/ few species of plants/less variety of plants/few plant layers; 2. Few sources/types of food/feeding sites; 3. Few habitats/ niches; 4. Fewer (species of) herbivore so few (species of) carnivores; 5. Aspect of agriculture (killing insects);
29
The points on the graph have been joined with straight lines rather than with a smooth curve. Explain why they have been joined with straight lines.
-Cannot predict/ do not know intermediate values;
30
It would have been useful to have had a control ditch in this investigation. Explain why.
To see what would happen/ compare with no | management work/ to see if numbers fell anyway/ To show that it was not a factor;
31
The gene that codes for this enzyme may be passed from one species of bacteria to another species. Describe how.
1. Horizontal (gene) transmission; | 2. (Gene passed by) conjugation/through pilus;
32
how adding antibiotics to the food of the cattle increased profit for the farmers
1. Kills pathogenic/harmful bacteria/pathogens; 2. Disease less likely/improves health/animals healthier/reduces spread of infection; 3. Faster growth/more productive animals/more food converted to meat/greater survival/lower vet‟s bills/increased yield/less energy (for „fighting infection‟);
33
Adding antibiotics to the food of cattle is now banned in many countries. Use your knowledge of selection to explain why adding antibiotics was banned.
1. (Adding antibiotics) selects in favour of antibiotic resistance/resistant bacteria more likely to survive; 2. Increase in numbers/higher proportion of resistant bacteria; 3. May infect humans/may spread resistance to other species/ horizontal transfer;
34
suggest an explanation for the difference in transpiration rate between conditions A (still air- 1.2 rate) and B (moving air-1.7 rate)
- 1. Removes water vapour/moisture/saturated air; | 2. Increases water potential gradient/more diffusion/more evaporation;
35
``` Suggest an explanation for the difference in transpiration rate between conditions A (15 degrees-1.2 rate) and C (26 degrees- 2.3 rate) ```
1. Increases kinetic energy; 2. Water molecules move faster; 3. Increases diffusion/evaporation;
36
Arteries and arterioles take blood away from the heart. | Explain how the structures of the walls of arteries and arterioles are related to their functions.
Elastic tissue 1 Elastic tissue stretches under pressure/when heart beats; 2 Recoils/springs back; 3 Evens out pressure/flow; Muscle 4 Muscle contracts; 5 Reduces diameter of lumen/vasoconstriction/constricts vessel; 6 Changes flow/pressure; Epithelium 7 Epithelium smooth; 8 Reduces friction/blood clots/less resistance;
37
The scientists also measured the diameter of the trunk of the tree on which the twig had been growing. The diameter was less at 12.00 than it was at 03.00 hours. Explain why the diameter was less at 12.00 hours.
1. Water pulled up trunk/moves up at fast rate; 2. (Water column under) tension; 3. Sticking/adhesion (between water and) cells/walls/xylem; 4. Pulls xylem in;
38
The biologists measured the maximum diameter of each shrimp’s eye. Explain why they measured the maximum diameter.
-(So results) can be compared/so measurement is the same each time/because eye is not perfectly round/uniform;
39
Standard deviation advantages
1. Standard deviation gives a measure of spread/variation; 2. More standard deviations overlap, the less likely it is that differences are real/significant/the more likely they are caused by chance;
40
The process in which cells become adapted for different functions
-Differentiation/specialisation
41
way in which this plant cell is adapted for photosynthesis
- Chloroplasts absorb light - Large vacuole pushes chloroplasts to the edge of the cell - Thin/permeable cell wall absorbs carbon dioxide
42
Classifying species
-kingdom, phylum, class, order, family, genus, species
43
What is meant by a hierarchy
- groups within larger groups | - no overlap
44
How scientists around the world used photographs to establish the relationship of gladiators to other insects
-Comparison of/look for similar features/structures/appearance
45
how a change in a sequence of DNA bases could result in a non-functional enzyme
- a change in the sequence of amino acids/primary structure - causes a change in hydrogen/ionic/disulfide bonds - which alters tertiary structure/active site of enzyme - so substrate cannot bind and no enzyme-substrate complexes form
46
How an increase in respiration in the tissues of a mammal affects the oxygen dissociation curve of haemoglobin
- increase in carbon dioxide | - so the curve moves to the right/depressed
47
why it was important that the piece of the epidermis that the student removed was thin- microscopes
- so there is a single/few layers of cells | - so that light can pass through/cells absorb light
48
how the student could have used his slide to find the number of stomata per cm2
- by using a method of determining area of field of view/area seen using microscope - by counting the number of stomata in field of view - and using repeats and calculating a mean
49
The stomata on the leaves of pine trees are found in pits below the leaf surface. Explain how this helps to reduce water loss
- water vapour accumulates / increased humidity/ reduced air movement around stomata - so water potential/diffusion gradient is reduced
50
How blood plasma is different from tissue fluid
-more/larger proteins / less urea/carbon dioxide / more glucose/amino acids/fatty acids/oxygen/ high(hydrostatic) pressure
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