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Biology Year 12 > past paper questions paper 1 > Flashcards

past paper questions paper 1 Flashcards

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1
Q

Compare and contrast the structure and properties of triglycerides and phospholipids (5) 2018 paper.

A
  • Triglycerides have 3 fatty acids and 1 glycerol. Phospholipids have 2 fatty acids , 1 glycerol and a phosphate group.
  • Triglycerides are hydrophobic (polar) and phospholipids have a hydrophobic and hydrophilic region (non-polar).
  • Phospholipids form a bilayer but triglycerides don’t .
  • Both contain glycerol
  • Both are insoluble
  • Both have ester bonds
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2
Q

Explain how the counter - current principle allows efficient oxygen uptake in the fish gas exchange system (2) 2021 paper 1

A
  • Blood and water flow in opposite directions.
  • Concentration gradient maintained along lamella
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3
Q

Describe the induced - fit model of enzyme action and how an enzyme acts as a catalyst (3) 2021 paper 1

A
  • Substrate binds to active site
  • Active site changes shape so it’s complementary to the shape of the substrate
  • Reduces activation energy
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4
Q

Describe how one amino acid is added to a polypeptide that is being formed at a ribosome during translation (3) 2021 paper 1

A
  • tRNA brings a specific amino acid
  • Anticodon on tRNA binds to codon on mRNA
  • Amino acids join by condensation reaction
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5
Q

Describe how a sample of chloroplasts could be isolated from leaves (4) 2021 paper 1

A
  • Blend cells and FILTER
  • In cold , same water potential , pH controlled solution.
  • Centrifuge and remove cell debris
  • Centrifuge at higher speeds , chloroplasts settled out.
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6
Q

Use your knowledge of phagocytosis to describe how an ADC ( molecules that are made up of a monoclonal antibody linked to a cancer drug) enters and kills the tumour cell (3) 2021 paper 1

A
  • Cell engulfs antibody / ADC
  • Lysosomes fuse with phagosome
  • Lysozymes digest ADC / antibody to release drug
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7
Q

Describe how a triglyceride molecule is formed (3) 2021 paper 1

A
  • Three fatty acids and a glycerol.
  • Condensation reaction and removal of three molecules of water
  • Ester bonds formed
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8
Q

Describe the structure of DNA (5) 2021 paper 1

A
  • Double helix
  • Contains a deoxyribose sugar , phosphate group and a nitrogenous base
  • Hydrogen bonding between complementary base pairings
  • Adenine pairs with thymine
  • Cytosine pairs with guanine
  • Phosphodiester bonds between nucleotides
  • Polynucleotide
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9
Q

Name and describe five ways substances can move across the cell - surface membrane into a cell. (5) 2021 paper 1

A
  1. Simple diffusion of small molecules down a concentration gradient.
  2. Facilitated diffusion down a concentration gradient via protein channel / carrier protein
  3. Osmosis of water down a water potential gradient
  4. Active transport against a concentration gradient via protein carrier using ATP
  5. Co- transport of 2 different substances using a carrier protein.
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10
Q

Describe how a non-competitive inhibitor can reduce the rate of an enzyme - controlled reaction (3) 2019 paper 1

A
  • Non competitive inhibitor binds to allosteric region of the enzyme
  • This changes the shape of the active site
  • No longer complementary so less substrate binds.
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11
Q

Describe the structure of human immunodeficiency virus (HIV) (4) 2019 paper 1

A
  • Attachment proteins
  • RNA
  • capsid
  • phospholipid envelope
  • Reverse transcriptase
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12
Q

Use your knowledge of gas exchange in leaves to explain why plants grown in soil with very little water grow only slowly (2) 2019 paper 1

A
  • Stomata closes if there’s very little water
  • Less Co2 uptake so less photosynthesis and less glucose production .
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13
Q

Explain 5 properties that make water important for organisms (5) 2019 paper 1

A

1) metabolite in condensation / hydrolysis reactions
2) A solvent so metabolic reactions can occur
3) High heat capacity so buffers changes in temperature
4) Cohesion so supports columns of water in plants
5) Large latent heat of vaporisation so provides a cooling effect

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14
Q

Describe the biochemical tests you would use to confirm the presence of a lipid , non- reducing sugar and amylase in a sample. (5) 2019 paper 1

A

LIPID :
1) Add ethanol
2) Add water
3) Shake
4) White emulsion formed
NON-REDUCING SUGAR :
1) Do Benedict’s test and stays blue ( no colour change)
2) Boil with HCl
3) Neutralise with alkali
4) Heat with Benedict’s and becomes red / orange
AMYLASE:
1) Add biuret and turns purple
2) Add starch , test for reducing sugar

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15
Q

Describe the chemical reactions involved with the conversions of polymers to monomers and monomers to polymers.
Give TWO names examples of polymers and their associated monomers to illustrate your answer . (5) 2019 paper 1

A
  • A condensation reaction joins two monomers together and forms a chemical bond and releases water.
  • A hydrolysis reaction breaks the chemical bond between monomers and uses water.
  • Amino acids join via a condensation reaction , forming peptide bonds to make a polypeptide chain.
  • Alpha glucose joins via a condensation reaction , forming glycosidic bonds to make starch.
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16
Q

Describe the structure and function of the nucleus (4) 2022 paper 1

A

Functions :
- Storing DNA for polynucleotide production.
- Where the production of mRNA takes place.
Structure :
- Nuclear envelope and pores for passage of mRNA.
- Nucleolus

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17
Q

Explain how the use of antibiotics has led to antibiotic - resistant strains of bacteria becoming a common cause of infection acquired when in hospital. (3) 2022 paper 1

A
  • Some bacteria have alleles for resistance of antibiotics.
  • Resistant bacteria survive and reproduce .
  • So high frequency of resistant allele in the bacterial population.
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18
Q

Describe viral replication (3) 2022 paper 1

A
  • Attachment proteins bind to receptors on a host cell.
  • Nucleic acids enters cell
  • Reverse transcriptase makes DNA from RNA
  • Cell produces viral proteins
  • Virus assembled and released from cell
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19
Q

Define the quaternary structure of a protein (1) 2022 paper 1

A

A chain of more than one polypeptides joined together forming a complex protein .

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20
Q

Explain how two enzymes with different amino acid sequences can catalyse the same reaction (2) 2022 paper 1

A

Both have an active site complementary to substrate so it forms enzyme - substrate complexes .
Similar tertiary structure at the active site

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21
Q

Describe the transport of carbohydrate in plants (5) 2022 paper 1

A
  • Sucrose is actively transported into phloem .
  • By companion cells
  • Lowers water potential of phloem so water from xylem enters phloem by osmosis.
  • Produces high hydrostatic pressure
  • Mass flow to respiring cells
  • Removed from phloem by active transport
22
Q

Compare and contrast the structure of starch and the structure of cellulose (6) 2022 paper 1

A
  • Both glucose polymers
  • Both contain glycosidic bonds
  • Both contain carbon , oxygen and hydrogen
  • Starch = branched
  • Cellulose = unbranched
  • Starch = alpha glucose
  • Cellulose = beta glucose
  • Cellulose forms fibrils , starch doesn’t
23
Q

Describe the complete digestion of starch by a mammal (4)

A
  • Hydrolysis of glycosidic bonds
  • Starch to maltose by amylase
  • Maltose to glucose by maltase
  • membrane - bound disaccharidases
24
Q

describe how a peptide bond is formed between two amino acids to form a dipeptide (2)

A

Two amino acids join together via a condensation reaction.
Between amine groups and carboxyl groups

25
Q

The secondary structure of a polypeptide is produced by bonds between amino acids . Describe how. (2)

A
  • Hydrogen bonds
  • Between NH and C=O group
26
Q

Two proteins have the same number and type of amino acids but different tertiary structure . Explain why (2)

A
  • Different primary structure
  • Forms hydrogen / ionic / disulphide bonds in different places
27
Q

Describe how the structure of glycogen is related to its function (4)

A
  • insoluble so doesn’t affect water potential
  • branched so many glucose tightly compact
  • branched do more ends for faster hydrolysis
  • Polymer of glucose so easily hydrolysed
28
Q

State and explain the property of water that can help to buffer changes in the temperature (2)

A
  • water has a high specific heat capacity
  • takes a lot of energy to change temperature
29
Q

Eukaryotic cells produce and release proteins .
Outline the role of organelles in the production of, transport and release of proteins from eukaryotic cells.
Do not include details of transcription and translation in your answer (4)

A
  • Rough endoplasmic reticulum produce protein
  • Golgi apparatus package proteins
  • DNA in nucleus is code for protein
  • Mitochondria produce ATP for protein synthesis
30
Q

Mammals such as a mouse and a horse are able to maintain a constant body temperature.
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 higher surface area to volume ratio
  • Has more and faster heat loss
  • Faster rate of respiration releases heat
31
Q

Describe the advantage of the Bohr effect during intense exercise (2)

A
  • increased dissociation of oxygen from haemoglobin
  • for aerobic respiration at the cells
32
Q

Describe the role of micelles in the absorption of fats into the cells lining the ileum (3)

A

1) micelles include bile salts and fatty acids
2) make fatty acids more soluble in water
3) bring fatty acids to lining of ileum
4) maintain high concentration of fatty acids to lining of ileum
5) fatty acids absorbed by diffusion

33
Q

Describe how a gene is a code for the production of a polypeptide . Do not include information about transcription or translation in your answer . (3)

A

• nucleotide sequence
• is in triplets
• this determines order of amino acid sequence in polypeptide

34
Q

Suggest and explain one advantage and one disadvantage to a farmer of replanting hedges on the farmland (2)

A

Advantage :
More biodiversity so increase in predators of pests
Disadvantage:
Reduced area for crop growth

35
Q

Give three structural features found in all virus particles and describe the function of one of these features (2) 2023 paper 1

A

1) capsid
2) attachment proteins
3) genetic material

Attachment proteins bind to receptors on cells

36
Q

Explain why viruses are described as acellular and non living (1) 2023 paper 1

A

Don’t have a cell surface membrane
Cannot move independently

37
Q

Give one reason why antibiotics are not effective against viruses (1) 2023 paper 1

A

Do not have bacterial structures

38
Q

Chitin keeps the tracheae open in the tracheal system of gas exchange in an insect. Gas exchange does not occur in the tracheae.
Explain the importance of one adaptation of the gas exchange surface in the tracheal system of the insect. (2) 2023 paper 1

A
  • tracheole is one cell thick
  • So shorter diffusion pathway
39
Q

Lignin is a polymer found in walls of xylem vessels in plants. Lignin keeps the xylem vessel open as a continuous tube.
Explain the importance of xylem being kept open as a continuous tube . (3) 2023 paper 1

A
  • Allows a water column
  • cohesion between H bonds between all water molecules
  • transpiration creates tension in column
40
Q

Describe 2 functions of the Golgi apparatus in a eukaryotic cell (2)

A
  • modifies and packages proteins
  • modifies and packages lipids
41
Q

Explain why the damage to the cells lining the ileum reduces absorption of the products of digestions and why this reduces absorption of water . (3) 2023 paper 1

A
  • reduces surface area
  • decreases water potential
  • so water moves out of cells and into ileum via osmosis
42
Q

To be used as passive immunity treatment , the anti toxin antibody would be injected.
If it was given by mouth , it would be digested .
describe how the anti toxin antibody would be digested . (3) 2023 paper 1

A
  • peptide bonds hydrolysed
  • Endopeptidases break internal peptide bonds
  • Exopeptidases break terminal peptide bonds
  • dipeptidases break dipeptides to amino acids
43
Q

Describe aseptic techniques she should use (3) 2023 paper 1

A

• wash hands with soap
• flame neck of bottle
• lift lid of agar plate at an angle

44
Q

Define genome and proteome (2) 2023 paper 1

A

Genome :
Complete set of genes in a cell

Proteome :
Full range of proteins that a cell can produce

45
Q

Suggest why several bacterial species have been renamed in recently years (1) 2023 paper 1

A

DNA base sequencing

46
Q

Suggest what is on the test at line T and explain what caused the line to appear in a positive test (elisa test) (2) 2023 paper 1

A

Antigen at T
Enzyme substrate complex produces a line

47
Q

A line at C shows that the test had worked.
Suggest one reason why a line at C shows the test has worked . (elisa test ) (1) 2023

A

Sample has diffused

48
Q

The dengue virus causes damage to capillaries so that blood proteins move out of the capillaries into the tissue fluid .
Explain how this would affect the return of tissue fluid into capillaries (2)

A
  • Increased water potential of blood
  • So less water returns to blood by osmosis
49
Q

Describe how a quaternary protein is formed from its monomers (5) 2023 paper 1

A
  • Amino acids joined by peptide bonds
  • By condensation reactions
  • Secondary structure is formed by hydrogen bonding
  • Tertiary structure is formed by interactions between R groups
  • Quaternary structure contains more than one polypeptide
50
Q

Describe the structure of DNA and the structure of a chromosome (6) 2023 paper 1

A
  • Polymer of nucleotides
  • Nucleotide consists of deoxyribose , phosphate and a nitrogenous base .
  • Phosphodiester bonds between nucleotides
  • DNA double helix held by hydrogen bonds
  • Hydrogen bonds between adenine and thymine , guanine and cytosine
  • DNA associated with histones
  • During mitosis , chromosomes consist of two chromatids joined at a centromere
51
Q

Mutation can result in an increase in genetic variation within a species .
Describe and explain the other processes that result in increases in genetic variation within a species . (4) 2023 paper 1

A
  • Independent segregation of homologous chromosomes
  • Crossing over between homologous chromosomes
  • Random fertilisation of gametes
  • Produces new combinations of alleles

Biology Year 12 (7 decks)

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