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BIOLOGY > 5-6 MARKERS > Flashcards

5-6 MARKERS Flashcards

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1
Q

Compare and contrast the structure and properties of triglycerides and phospholipids.

A

COMPARE:
• Both have ester bonds and contain glycerol
• Fatty acids may both be saturated or unsaturated
• Both are insoluble in water
• Both contain C, H and O
CONTRAST
• Triglyceride has 3 fatty acids whereas phospholipids have 2 fatty acids plus PO43- group.
• Triglycerides are hydrophobic/non-polar whereas phospholipids have both a hydrophilic and hydrophobic region
• Phospholipids form monolayer/micelle/bilayer whereas triglycerides don’t.

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2
Q

Describe how the structures of starch and cellulose molecules are related to their functions. (5)

A

Starch (max 3)
1. Helical/ spiral shape so compact;
2. Large (molecule)/insoluble so osmotically inactive;
3. Branched so glucose is (easily) released for respiration;
4. Large (molecule) so cannot leave cell/cross cell-surface membrane;
Cellulose (max 3)
5. Long, straight/unbranched chains of β glucose;
6. Joined by hydrogen bonding;
7. To form (micro/macro)fibrils;
8. Provides rigidity/strength;

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3
Q

Explain why the diffusion of chloride ions involves a membrane protein and the diffusion of oxygen does not. (5)

A
  1. Chloride ions water soluble/charged/polar;
  2. Cannot cross (lipid) bilayer (of membrane);
  3. Chloride ions transported by facilitated diffusion OR diffusion involving channel/carrier protein;
  4. Oxygen not charged/non-polar;
  5. (Oxygen) soluble in/can diffuse across (lipid) bilayer;
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4
Q

Use your knowledge of protein structure to explain why enzymes are specific and may be affected by non-competitive inhibitors. (5)

A

1 each enzyme / protein has specific primary structure / amino acid sequence;
2 folds in a particular way / has particular tertiary structure giving an active site with a unique structure;
3 shape of active site complementary to / will only fit that of substrate;
4 inhibitor fits at site on the enzyme other than active site;
5 distorts active site;
6 so substrate will no longer fit / form enzyme-substrate complex

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5
Q

Describe the role of the enzymes of the digestive system in the complete breakdown of starch. (5)

A

Amylase;
(Starch) to maltose:
Maltase;
Maltose to glucose;
Hydrolysis;
(Of) glycosidic bond;

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6
Q

Describe the role of the enzymes of the digestive system in the complete breakdown of starch. (5)

A

Amylase;
(Starch) to maltose:
Maltase;
Maltose to glucose;
Hydrolysis;
(Of) glycosidic bond;

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7
Q

In humans, the enzyme maltase breaks down maltose to glucose. This takes place at normal body temperature.
Explain why maltase:
-only breaks down maltose
-allows this reaction to take place at normal body temperature. (5)

A
  1. Tertiary structure / 3D shape of enzyme (means);
  2. Active site complementary to maltose / substrate / maltose fits into active site / active site and substrate fit like a lock and key;
  3. Description of induced fit;
  4. Enzyme is a catalyst;
  5. Lowers activation energy / energy required for reaction;
  6. By forming enzyme-substrate complex;
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8
Q

Scientists have investigated the effects of competitive and non-competitive inhibitors of the enzyme maltase.
Describe competitive and non-competitive inhibition of an enzyme. (5)

A
  1. Inhibitors reduce binding of enzyme to substrate / prevent formation of ES complex;
    (Competitive inhibition),
  2. Inhibitor similar shape (idea) to substrate;
  3. (binds) in to active site (of enzyme);
  4. (Inhibition) can be overcome by more substrate;
    (Non-competitive inhibition),
  5. Inhibitor binds to site on enzyme other than active site;
  6. Prevents formation of active site / changes (shape of) active site;
  7. Cannot be overcome by adding more substrate;
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9
Q

Explain how the structure of DNA is related to its functions. (6)

A
  1. Sugar-phosphate (backbone)/double
    stranded/helix so provides strength/stability
    /protects bases/protects hydrogen bonds;
  2. Long/large molecule so can store lots of
    information;
  3. Helix/coiled so compact;
  4. Base sequence allows information to be
    stored/ base sequence codes for amino
    acids/protein;
  5. Double stranded so replication can occur
    semi-conservatively/ strands can act as
    templates;
  6. Complementary base pairing / A-T and G-C
    so accurate replication/identical copies can
    be made;
  7. (Weak) hydrogen bonds for replication/
    unzipping/strand separation;
  8. Many hydrogen bonds so stable/strong;
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10
Q

Atheroma formation increases a person’s risk of dying. Explain how. (5)

A
  1. Atheroma is fatty material/cholesterol/foam cells/plaque/calcium deposits/LDL;
  2. In wall of artery;
  3. (Higher risk of) aneurysm/described;
  4. (Higher risk of) thrombus formation/blood clot;
  5. Blocks coronary artery;
  6. Less oxygen/glucose to heart muscle/cells/tissue;
  7. Reduces/prevents respiration;
  8. Causing myocardial infarction/heart attack;
  9. Blocks artery to brain;
  10. Causes stroke/stroke described;
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11
Q

Describe how DNA is replicated. (6)

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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12
Q

Describe how tissue fluid is formed and how it is returned to the circulatory system. (6)

A

Formation
1. High blood / hydrostatic pressure /
pressure filtration;
2. Forces water / fluid out;
3. Large proteins remain in capillary;
Return
4. Low water potential in capillary /
blood;
5. Due to (plasma) proteins;
6. Water enters capillary / blood;
7. (By) osmosis;
8. Correct reference to lymph;

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13
Q

Some substances can cross the cell-surface membrane of a cell by simple diffusion through the phospholipid bilayer.
Describe other ways by which substances cross this membrane. (5)

A

By osmosis (no mark)
1. From a high water potential to a low water potential/down a water potential gradient;
2. Through aquaporins/water channels;
By facilitated diffusion (no mark)
3. Channel/carrier protein;
4. Down concentration gradient;
By active transport (no mark)
5. Carrier protein/protein pumps;
6. Against concentration gradient;
7. Using ATP/energy (from respiration);
By phagocytosis/endocytosis (no mark)
8. Engulfing by cell surface membrane to form vesicle/vacuole;
By exocytosis/role of Golgi vesicles (no mark)
9. Fusion of vesicle with cell surface membrane;

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14
Q

The events that take place during interphase and mitosis lead to the production of two genetically identical cells. Explain how. (4)

A
  1. DNA replicated;
  2. (Involving)
    specific/accurate/complementary
    base-pairing;
  3. (Ref to) two identical/sister
    chromatids;
  4. Each chromatid/ moves/is separated
    to(opposite) poles/ends of cell;
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15
Q

A mutation can lead to the production of a non-functional enzyme. Explain how. (6)

A
  1. Change/mutation in base/nucleotide
    sequence (of DNA/gene);
  2. Change in amino acid
    sequence/primary structure (of
    enzyme);
  3. Change in hydrogen/ionic/disulfide
    bonds;
  4. Change in the tertiary
    structure/shape;
  5. Change in active site;
  6. Substrate not complementary/cannot
    bind (to enzyme/active site) / no
    enzyme-substrate complexes form;
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16
Q

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta. (5)

A
  1. Atrium has higher pressure than ventricle (due to filling/contraction);
  2. Atrioventricular valve opens;
  3. Ventricle has higher pressure than atrium (due to filling/contraction);
  4. Atrioventricular valve closes;
  5. Ventricle has higher pressure than aorta;
  6. Semilunar valve opens;
  7. Higher pressure in aorta than ventricle (as heart relaxes);
  8. Semilunar valve closes;
  9. (Muscle/atrial/ventricular) contraction causes increase in pressure;
17
Q

Explain how selection occurs in living organisms (6)

A
  1. Variation due to mutation;
  2. Different environmental/ abiotic/biotic conditions / selection pressures;
  3. Selection for different/ advantageous, features/ characteristics/mutation/ /allele;
  4. Differential reproductive success / (selected) organisms survive and reproduce;
  5. Leads to change in allele frequency;
  6. Occurs over a long period of time;
18
Q

RP7
Outline the procedure of using chromatography to separate photosynthetic pigments (6)

A
  1. Draw the origin pencil line 1cm from the bottom
  2. Add 2cm^3 of acetone and use the mortar and pestle to grind up leaf sample and release the pigments
  3. Use a capillary tube to transfer the pigment onto the origin
  4. Place filter paper in solvent (below pencil line) and leave until solvent is 1cm from top
  5. Remove paper from solvent and draw solvent front
  6. Calculate Rf value for each spot
19
Q

Describe the process of succession

A

Pioneers cause change in environmental abiotic / biotic factors (give an example);
• Pioneers make the environment less hostile for new species;
• New species change/make conditions less suitable for previous species;
• Change/increase in diversity/biodiversity;
• Stability increases population/richness/abiotic factors:
• Climax community;

20
Q

Explain how water enters the xylem from the endodermis in the root and is then transported to the leaves (6)

A

(In the root)
1. Casparian strip blocks apoplast pathway / only allows symplast pathway;
2. Active transport by endodermis;
3. (Of) ions into xylem;
4. Lower water potential in xylem so water enters by osmosis/down water potential gradient;

(Xylem to leaf)
5. Transpiration (from leaves);
6. (Creates) cohesion / tension / H bonds between H2O / NEGATIVE PRESSURE;
7. Adhesion / H20 binds to xylem;
8. (Creates) continuous column of water.

21
Q

Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer (7)

A
  1. Some light energy fails to strike/is reflected/not of appropriate wavelength;
  2. Efficiency of photosynthesis in plants is low/around 2% efficient;
  3. Respiratory loss / excretion / faeces / not eaten;
  4. Loss as heat;
  5. Efficiency of transfer to consumers greater than transfer to producers/approximately 10%;
  6. Efficiency lower in older animals/herbivores/primary consumers/warm blooded animals;
  7. Carnivores use more of their food than herbivores;
22
Q

The concentrations of carbon dioxide in the air at different heights above ground in a forest changes over a period of 24 hours.
Use your knowledge of photosynthesis to describe these changes and explain why they occur (6)

A
  1. High concentration of carbon dioxide linked with night/darkness;
  2. No photosynthesis at night/in dark/light required for photosynthesis/light-dependent reaction;
  3. (In dark) plants (and other organisms) respire;
  4. In light net uptake of carbon dioxide by plants/plants use more carbon dioxide than they produce/ rate of photosynthesis greater than rate of respiration;
  5. Decrease in carbon dioxide concentration with height;
  6. At ground level fewer leaves/less photosynthesising tissue/more animals/less light.
23
Q

Describe how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium of the aorta.

A
  1. Atrium has higher pressure than ventricle (due to filling/contraction);
  2. (so) Atrioventricular valve opens;
  3. Ventricle has higher pressure than atrium (due to filling/contraction);
  4. (so) Atrioventricular valve closes;
  5. Ventricle has higher pressure than aorta;
  6. (so) Semilunar valve opens;
  7. Aorta has higher pressure than ventricle;
  8. (so) Semilunar valve closes;
  9. (Muscle/atrial/ventricular) contraction causes increase in pressure.
24
Q

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

A
  1. Named structures O2 IN - Trachea, Bronchi, Bronchioles, Alveoli
  2. BREATHING IN/INHALATION - Diaphragm contract and external intercostal muscles contract, volume increase and pressure in thoracic cavity decrease;
  3. BREATHING OUT/EXHALATION - Diaphragm relaxes and internal intercostal muscles contract, volume decrease and pressure increase in thoracic cavity.

BIOLOGY (28 decks)

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