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Biology: AQA A-Level > Essay > Flashcards

Essay Flashcards

(101 cards)

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1
Q

What topics fit into almost every essay?

A

Photosynthesis, Respiration, Protein Synthesis, Immunology, Synapse, Receptors & Homeostasis.

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2
Q

What absorbs light energy in the light-dependent reaction?

A

Chlorophyll.

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3
Q

What happens to chlorophyll when it absorbs light?

A

It excites electrons.

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4
Q

What is the process called when electrons are removed from chlorophyll?

A

Photoionization.

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5
Q

How do electrons move after being excited?

A

Along the electron transport chain.

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6
Q

What does the energy from electrons do?

A

It forms a proton gradient.

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7
Q

How do H⁺ ions contribute to ATP production?

A

They move through ATP synthase, forming ATP.

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8
Q

What is photolysis?

A

Water splitting, producing 2 protons, 2 electrons, and ½ oxygen.

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9
Q

What happens to NADP in the light-dependent reaction?

A

It is reduced by electrons and protons.

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10
Q

What combines with CO₂ in the light-independent reaction?

A

Ribulose bisphosphate (RuBP).

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11
Q

What does RuBP and CO₂ form?

A

Two glycerate-3-phosphate (GP) molecules.

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12
Q

Which enzyme catalyzes the reaction between CO₂ and RuBP?

A

Rubisco.

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13
Q

What happens to GP in the light-independent reaction?

A

It is reduced to triose phosphate using ATP and reduced NADP.

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14
Q

What can triose phosphate form?

A

Glucose, hexose, RuBP, or other organic substances.

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15
Q

Why do plants with more chlorophyll grow faster?

A

Faster production of ATP and reduced NADP.

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16
Q

What does faster ATP production lead to?

A

Faster light-independent reactions and more sugars for respiration.

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17
Q

How does more chlorophyll affect energy for growth?

A

It provides more energy for faster growth.

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18
Q

What happens first in glycolysis?

A

Glucose is phosphorylated using ATP.

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19
Q

What is the product of phosphorylated glucose?

A

Triose phosphate.

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20
Q

What happens to triose phosphate in glycolysis?

A

It is oxidized to pyruvate.

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21
Q

How much ATP is produced in glycolysis?

A

A net gain of ATP.

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22
Q

What happens to NAD in glycolysis?

A

It is reduced to NADH.

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23
Q

How is oxidation carried out in glycolysis and Krebs cycle?

A

Removal of hydrogen (dehydrogenation) by dehydrogenase enzymes.

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24
Q

What accepts the hydrogen during oxidation?

A

NAD (and FAD in the Krebs cycle).

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25
What does NAD become after accepting hydrogen?
Reduced NAD.
26
What happens to pyruvate and acetyl CoA inside mitochondria?
Electrons and H⁺ ions are oxidized.
27
Where is ATP produced in the mitochondria?
In the Krebs cycle via substrate-level phosphorylation.
28
What is produced in addition to ATP during oxidation in the mitochondria?
Reduced NAD and FAD.
29
What happens in the electron transport chain (ETC)?
Electrons pass through the chain, releasing energy.
30
What do protons do during oxidative phosphorylation?
They move into the intermembrane space.
31
How does ATP synthase contribute to ATP production?
It uses energy from protons moving back to form ATP.
32
Why do muscle cells have many cristae?
To increase surface area for the electron transport chain.
33
How does more cristae benefit muscle cells?
More ATP produced for muscle contraction.
34
What happens to DNA during transcription?
Hydrogen bonds between DNA bases break.
35
What strand acts as a template in transcription?
One DNA strand.
36
How do RNA nucleotides align during transcription?
By complementary base pairing (Uracil pairs with Adenine).
37
What does RNA polymerase do?
Joins adjacent RNA nucleotides by phosphodiester bonds.
38
What happens to pre-mRNA in eukaryotes?
It is spliced to form mRNA.
39
Where does mRNA attach during translation?
To ribosomes or the rough endoplasmic reticulum.
40
What does tRNA do during translation?
tRNA anticodons bind to complementary mRNA codons.
41
What does tRNA bring to the ribosome?
A specific amino acid.
42
How are amino acids joined in translation?
By peptide bonds via a condensation reaction.
43
What happens to the ribosome during translation?
It moves along mRNA to form the polypeptide.
44
How does a mutation affect an enzyme?
It changes the DNA sequence of the gene.
45
What does a change in the gene sequence alter?
The amino acid sequence of the enzyme.
46
How do altered bonds affect the enzyme’s function?
They disrupt hydrogen, ionic, or disulfide bonds.
47
How does the enzyme's structure change?
The active site is altered, preventing substrate binding.
48
Where is the protein code found in eukaryotic cells?
In the DNA of the nucleus.
49
What organelles are involved in protein synthesis?
Ribosomes and the rough endoplasmic reticulum.
50
What provides ATP for protein synthesis?
Mitochondria.
51
How are proteins modified and packaged?
By the Golgi apparatus.
52
How are proteins transported to the cell surface?
In vesicles.
53
What happens during phagocytosis?
A pathogen is engulfed by a phagocyte.
54
What happens to the pathogen once inside the phagocyte?
It enters the cytoplasm in a vesicle (phagosome).
55
What happens when the phagosome fuses with a lysosome?
Hydrolytic enzymes digest the pathogen.
56
What happens to the waste after digestion?
It is ejected via exocytosis.
57
What does the phagocyte do after digestion?
It presents antigens on its surface.
58
How does HIV replicate inside T cells?
RNA is converted into DNA by reverse transcriptase.
59
What happens to HIV DNA once inside the host cell?
It integrates into the host genome.
60
What happens after HIV DNA integrates?
HIV mRNA is transcribed.
61
What happens to the HIV mRNA?
It is translated into viral proteins for assembly.
62
How does HIV lead to AIDS?
High viral load destroys helper T cells.
63
What does the destruction of T cells result in?
Reduced activation of immune cells like B cells and cytotoxic T cells.
64
How does HIV affect immune defense?
The body becomes less able to fight other pathogens and infections.
65
What does a vaccine introduce?
Antigen from the pathogen.
66
What does a macrophage do with the antigen?
It presents it on its surface.
67
How do T helper cells respond to the antigen?
They bind to the antigen and become activated.
68
How do T helper cells help B cells?
They release cytokines to stimulate B cells.
69
What do B cells do after activation?
They divide and secrete antibodies.
70
How should you start an essay on the importance of membranes?
Start with a relevant topic/process involving a membrane.
71
What do you do after introducing the membrane?
Explain why the membrane is important (e.g., ATP production in photosynthesis).
72
How many topics should you cover in the essay?
3-4 other topics with a similar structure.
73
What is AO1 worth in an essay?
15 marks.
74
What is AO2 worth in an essay?
10 marks.
75
What’s the maximum score for an essay with no links?
15 marks.
76
How many topics do you need to cover for 15 marks?
At least 3 topics, each worth 5 marks.
77
How can you get 25 marks in an essay?
Use 5 x 5-mark AO1 topics.
78
How many of those topics should be linked to the essay?
All topics must be relevant and linked to the focus.
79
Can one topic be off-spec?
Yes, one topic can be off-spec at A-Level standard.
80
What should you avoid for a perfect score?
Biological errors and irrelevant content.
81
What happens first during acetylcholine release?
Depolarisation of the presynaptic membrane.
82
What opens after depolarisation?
Ca²⁺ channels.
83
What happens when calcium ions enter the synaptic knob?
Synaptic vesicles move and fuse with the presynaptic membrane.
84
What happens after vesicles fuse with the membrane?
Acetylcholine is released into the synaptic cleft.
85
How does acetylcholine reach the postsynaptic membrane?
It diffuses across the synaptic cleft.
86
What does acetylcholine do on the postsynaptic membrane?
It binds to receptors.
87
What does binding of acetylcholine cause?
Sodium ions enter the postsynaptic neurone, leading to depolarisation.
88
Why is increased cardiac output beneficial during exercise?
It delivers more oxygen and glucose to muscles.
89
What does this increased oxygen and glucose supply allow?
More ATP production via aerobic respiration.
90
How does this improve exercise performance?
It enhances the removal of CO₂ and lactate from muscles.
91
What forms between actin and myosin during muscle contraction?
Cross-bridges.
92
What happens in the power stroke of muscle contraction?
Myosin heads pull actin over myosin.
93
What is required for myosin heads to detach?
ATP.
94
What happens after myosin detaches?
The myosin heads return to their original position (recovery stroke).
95
What happens when GABA binds to receptors on the postsynaptic membrane?
The postsynaptic neurone becomes hyperpolarised.
96
How does hyperpolarisation affect action potential generation?
It makes it harder for the neurone to reach the threshold for depolarisation.
97
What happens to sodium ions during GABA binding?
Fewer sodium ions enter, preventing action potential generation.
98
What happens when DNA mutates?
The base sequence of a gene controlling cell growth is altered.
99
What effect does this mutation have on the enzyme produced?
It changes the enzyme's structure, making it non-functional.
100
How does this mutation affect cell division?
There’s no inhibition on cell division, leading to uncontrolled mitosis.
101
What is the result of uncontrolled mitosis?
Malignant tumour formation.

Biology: AQA A-Level (48 decks)

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