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Biology Exam Questions > Topic 1/2 > Flashcards

Topic 1/2 Flashcards

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1
Q

Describe and explain how lungs in mammals are adapted to gas exchange (5)

A
  • Alveolus and capillaries one cell thick
  • Alveoli closely associated with capillary, short diffusion distance, faster gas exchange
  • Alveoli provide large surface area, more efficient gas exchange
  • Concentration gradient maintained by breathing and constant supply of red blood cells from beating heart
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2
Q

Explain how dipolar nature of H2O is essential for organisms (2)

A

Biological solvent, water is polar meaning it can surround solvent molecules, forming hydrogen bonds allowing them to dissolve

High specific latent heat capacity means even if external environments change, water inside body can remain liquid/osmosis wont be effected

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3
Q

Suggest how heart of daphnia enables organs to carry out efficient gas exchange (2)

A
  • Blood carries Oxygen, Carbon dioxide
  • Blood maintains concentration gradient, more mass flow due to smaller volume
  • Large SA:V ratio in organs
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4
Q

Suggest how circulatory system enables mammals to carry out effective gas exchange (3)

A
  • One side of the heart transports blood to the lungs, the other to the rest of the body
  • Oxygenated and deoxygenated blood can be separated which maintains conc gradient
  • Good supply of Oxygen needed as mammals have high metabolic rates.
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5
Q

Explain why chemicals from whole heart needed to produce mature heart chemicals from immature heart cells (4)

A
  • Chemicals switch in some genes
  • This resulted in different (mature heart) genes bein expressed
  • mRNA transcribed from new active gene
  • Different mRNA causes different protein to be translated
  • Protein now determines structure in mature heart cells
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6
Q

Advantages of using mature heart cells for testing drugs )2)

A
  • Cells function like actual heart cells, less need to use animal testing
  • Clinical drugs trials will not be carried out unless the cell has a desired response to the drug
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7
Q

Describe contemporary drug testing protocols that could be used to test drugs developed for treating heart disease (3)

A
  • First test drug on small sample of healthy volunteers
  • Secondly test drug on small sample of patients
  • Thirdly test drug on a large sample of patients
    Include a placebo in phase 1/2 and use double blind trial to reduce investigator effects + demand characteristics
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8
Q

Explain how the structure of an artery is adapted to its function (4)

A
  • Thick collagen containing wall, allows it to withstand high blood pressure
  • Elastic fibres allow artery to stretch and recoil, blood still flows during diastole
  • Muscle fibres maintain BP
  • Smooth walls reduces peripheral resistance
  • Narrow lumen promotes high BP
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9
Q

Describe structure of mononucleotide found in RNA (2)

A 
Contains ribose sugar, phosphate and nitrogen containing bases:
Uracil
Adenine
Cytosine
Guanine
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10
Q

Describe process of protein synthesis in cytoplasm (5)

A
  • mRNA attaches to ribosome
  • tRNA carries amino acid to ribosome
  • tRNA with anticodon for mRNA codon complimentary base pairs forming hydrogen bonds
  • Amino acids brought by tRNA form peptide bonds in condensation reaction
  • tRNA moves away from mRNA, more amino acids are brought
  • Once stop codon is reached no more amino acids are added, polypeptide chain detaches from ribosome and translation is complete
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11
Q

Difference between saturated/un-saturated fatty acid (1)

A

Saturated fatty acids contain no double bonds in hydrocarbon chain while un-saturated fatty acids do

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12
Q

Explain why someone with high BP is at risk of developing CVD (4)

A
  • More likely damage to endothelial lining of artery causing inflammatory responses
  • Leading to formation of plaque/atheroma
  • Increased risk of blood clot formation
  • Loss of elasticity, narrowing of lumen
  • Positive feedback causes further high BP
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13
Q

State medical advice and how this reduces risk of CVD (3)`

A

Reduce energy intake, salt and cholesterol intake
less salt reduces high BP lower cholesterol reduces chance of atherosclerosis

Eat more fruit to increase antioxidants in body to protect against free radical damage to cells

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14
Q

Explain meaning of term recessive allele (3)

A
  • Both alleles need to be present in order for recessive phenotype to be expressed
  • Allele is the different form of the same gene
  • Located on the same locus on both genes
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15
Q

Explain why people with cystic fibrosis have breathing problems (4)

A
  • Produces thicker mucus, blocks airways
  • Cilia unable to move mucus out of lungs
  • Reduced flow of O2 to alveoli, reduces conc gradient of CO2/02 in alveoli
  • Reduces surface area of alveoli, reduces efficiency in gas exchange
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16
Q

Similarity between DNA and mRNA (1)

A

Both have a sugar-phosphate chain

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17
Q

Advantage of DNA having 2 complimentary strands (1)

A

Semi-conservative replication is possible

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18
Q

3 differences between replication and transcription of DNA (3)

A

Replication uses DNA nucleotides, transcription uses RNA nucleotides

Replication makes DNA double helix, transcription makes single strand molecule

Replication uses DNA polymerase

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19
Q

Suggest how new born babies can be tested fo disorders (2)

A
  • Obtain sample from baby, eg cheek swab
  • Extract DNA from cells
  • Test for presence of mutated allele
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20
Q

How can modified stem cells result in prevention of disorder (3)

A
  • Copy of normal gene now in cells
  • Normal gene can be transcribed and translated
  • Normal protein can be produced
  • Stem cells can divide to produce more cells
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21
Q

Why might parents consent to gene therapy for their children (2)

A
  • Concequence of disorder may be more certain than risk from therapy
  • Parents do not want child to suffer disorder
  • Trial may lead to effective treatment - benefits others
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22
Q

2 differences between structure of artery/capillary (2)

A

Arteries have thick collogen walls, capillarie have one cell thick endothelial wall

Arteries have elastic fibres, capillaries dont

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23
Q

Explain how anticoagulants reduce effects of CVD (2)

A
  • Prevent formation of blood clot
  • Reduces stickiness in platelets
  • Clotting factors arent synthesised
  • Less risk of blood vessel being blocked
24
Q

One risk associated with use of anticoagulants (1)

A

Prolonged bleeding

25
Q

Describe how one prenatal genetic test can be done (3)

A

Amniocentesis

  • Fetal cells obtained from amniotic fluid via thin needle
  • Cells tested for abnormal allele
26
Q

One ethical issue associated with prenatal testing (2)

A

May result in miscarŕiage

Killing is unethical

27
Q

One social issue associated with prenatal testing (2)

A

Risk of false positve test

Healthy fetus may be aborted

28
Q

Name one element present in amino acids, but not carbohydrates (1)

A

Nitrogen

29
Q

2 reasons why daphnia are used to test chemical effects on heart (2)

A
  • You can see heart through translucent body

- Chemicals can be easily absorbed from surrounding solution

30
Q

Explain why small animals have a heart (3)

A
  • Diffusion alone would be too slow
  • Oxygen needs to be transported to cells
  • Has high metabolic rate, fast gas exchange is vital
31
Q

How can change of amino acid lead to change in structure and properties of haemoglobin (5)

A
  • Change in primary structure
  • Different R group
  • Different ionic bonds can be made
  • Folding into 3D structure is different
  • Changes in properties of haemoglobin - eg oxygen can no longer bind
32
Q

How does rhythimic tapping of chest wall relieve symptoms of CF in lungs (2)

A
  • Loosens mucus
  • Mucus can be expelled from lungs more easily
  • Easier to breathe
33
Q

Explain two ways in which the structures of amylose and glycogen make them suitable energy stores (2)

A
  • Contain glucose
  • Compact, large mass of glucose molecules can fit into small volume
  • Insoluble, does not effect osmosis
34
Q

Two lifestyle changes that reduce risk of stroke (2)

A
  • Lower cholesterol diet

- Increase activity - exercise

35
Q

Explain how blood clot can cause heart attack (3)

A
  • Prevents Oxygen reaching heart muscle
  • Prevents aerobic respiration
  • Cardiac muscle unable to contract
36
Q

Similarity between active-transport and faciliated diffusion (1)

difference between active-transport and faciliated diffusion (1)

A

Similarity: Both use carrier proteins

Difference: Active transport requires energy, diffusion does not

37
Q

Describe structure of cell membrane (5)

A
  • Phospholipid bilayer
  • Hydrophillic phosphate heads project outwards and hydrophilic fatty acid tails face in/away from water
  • Heads are attracted to water, tails repel it
  • Proteins, glycoproteins and glycolipids
  • Cholesterol within membrane
38
Q

Explain why blood clot in artery leading to the brain can cause stroke (3)

A
  • Reduced blood flow, less oxygen reaches brain
  • Less aerobic respiration
  • Lactic acid produced from anaerobic respiration
39
Q

Two properties of molecules that allow them to enter cell by diffusion (2)

A

Small

Non-polar

40
Q

Explain what is meant by the term fluid mosaic (2)

A

Phospholipids are able to move

Proteins are scattered in the membrane

41
Q

Explain importance of water to plants (3)

A
  • Dissolves solutes and acts as a medium for biochemical reactions
  • Transports minerals to cells
  • Regulates temperature by evapotranspiration
42
Q

What is meant by the term template for synthesis of mRNA (1)

A

RNA nucleotides attach to this strand

Sequence of bases on template determine sequence of bases on mRNA

43
Q

Explain importance of nitrate ions in plants (2)

A
  • Produce amino acids

- Maintains chlorophyll levels in leaves

44
Q

Consequence of very low fat diet for active person (2)

A
  • Energy imbalance is created
  • Weight will be lost
  • Reduced metabolic rate
45
Q

Why can gene mutation result in enzyme unable to breakdown lipids (5)

A
  • Change in DNA base sequence
  • Change in primary structure of protein
  • Different R groups will lead to different bonding, for example ionic instead of hydrogen
  • Change in folding results in different 3D structure
  • Changed active site, lipids no longer fit into enzyme
46
Q

Compare and contrast the molecular structure of globular and fibrous proteins (4)

A
  • Both are chains of amino acids joined by peptide bonds
  • Both contain hydrogen bonds to maintain 3D shape
  • Globular have tertiary/quaternary structure, fibrous have little if any tertiary structure
  • Globular folded into compact shape, fibrous remain as long chains
47
Q

Describe roles of transcription and translation in the synthesis of a globular protein (5)

A
  • Gene for globular protein is transcribed
  • Complimentary base paring between RNA nucleotides and DNA to make mRNA
  • mRNA leaves nucleus, attaches to ribosome
  • mRNA binds to ribosome and provides specific amino acids
48
Q

Compare and contrast transcription with DNA replication (4)

A
  • Both form phosphodiester bonds
  • Both involve DNA helicase
  • Transcription uses RNA nucleotides
    Replication uses DNA nucleotides
  • Transcription used RNA polymerase
    Replication uses DNA polymerase
49
Q

Describe how MRNA is synthesised at a template strand of DNA (2)

A
  • RNA nucleotides align with complimentary bases on DNA

- RNA nucleotides joined by RNA polymerase

50
Q

Describe how glucose enters muscle cells through the cell membrane (2)

A
  • Carrier protein

- Enters by facilitated diffusion

51
Q

People with CF require high energy diet, they are more likely to develop problems in pancreas, men with CF less able to release sperm
Explain these symptoms (4)

A
  • Thicker mucus than normal
  • Enzymes can’t enter intestine, pancreatic duct blocked by mucus
  • Enzymes can damage pancreatic cells that produce insulin
  • Sperm can’t leave testes because sperm duct is blocked
52
Q

Compare and contrast the structure of ATP and DNA (3)

A
  • Both contain phosphate, ribose and a base
  • DNA contains deoxyribose, ATP has ribose
  • DNA has 1 phosphate, ATP is a triphosphate
53
Q

Compare and contrast the structure of collagen and an enzyme like arazyme (4)

A
  • Both are chains of amino acids joined by peptide bonds
  • Collagen is fibrous, arazyme is globular
  • Arazyme has an active site, collagen does not
  • Arazyme has amino acids on surface, collagen does not
54
Q

compare and contrast the structure of cellulose and amylopectin (4)

A
  • Both are polysaccharides
  • Both contain 1.4 glyosidic bonds
  • Amylopectin has 1.6 glyosidic bonds, cellulose does not
  • Amylopectin is branches, cellulose is a long chained molecule
55
Q

explain the effect of temperature on the rate of photosynthesis (3)

A
  • increasing temp increases kinetic energy of both molecules
  • molecules collide more
  • above (30 degrees) enzyme denatures
  • active site changes shape, rate decreases
56
Q

describe the function of carrier proteins in a cell surface membrane (4)

A
  • involved in facilitated diffusion
  • Movement of polar molecules
  • Involved in active transport
  • Uses ATP to move molecule against conc gradient

Biology Exam Questions (4 decks)

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