Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A level Bio > Exam questions > Flashcards

Exam questions Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Why are viruses acellular?

A
  • Don’t have a cell membrane
  • Not made of cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why are viruses non-living?

A
  • Can’t independently respire/replicate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe 2 functions of golgi apparatus:

A
  • Modifies and packages proteins
  • Modifies and packages lipids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a proteome?

A
  • All the range of proteins a cell can code for
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe how quaternary protein formed from its monomers

A
  • Amino acids joined by peptide bond(s);
  • (By) condensation reaction(s);
  • Secondary structure is formed by hydrogen
    bonding;
  • Tertiary structure formed by interactions
    (between R groups);
  • Quaternary structure contains >1 polypeptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe structure of DNA

A
  • Nucleotide= deoxyribose, phosphate and nitrogenous base
  • Phosphodiester bonds between nucleotides
  • Hydrogen bonding between adenine and thymine, and cytosine and guanine
  • Double helix structure
  • DNA is associated with histones
  • DNA is a polynucleotide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Give 2 reasons for conserving rainforests:

A
  • Medicine produced
  • Conserve plants/animals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe how DNA is related to its function:

A
  • Double-stranded allowing semi-conservative replication
  • Base sequence and complementary base pairing allowing accurate replication
  • Hydrogen bonds are weak so easily broken for replication
  • Large so can store a lot of information
  • Sugar-phosphate backbone provides strength
  • Helix so compact
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe ways in which all dipeptides are similar in which they might differ:

A

Similarities
- Consist of 2 amino acids
- Joined by peptide bond
- Contain amine group
- Contain carboxyl group
- Contain C,H,N and O

Differences
- Contain different amino acids
- Variable R group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe how a non-competitive inhibitor can reduce the rate of an
enzyme-controlled reaction

A
  • Binds to the allosteric site on enzyme
  • This changes the tertiary structure of the enzyme and so the active site no longer complementary
  • So enzyme-substrate complexes can no longer bind
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Two proteins have the same number and type of amino acids but different
tertiary structures.
Explain why:

A
  • Different sequence of amino acids
  • Results in ionic,hydrogen, disulphide bonds in different places
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe how a phosphodiester bond is formed between two nucleotides
within a DNA molecule.

A
  • Condensation reaction
  • Between phosphate and deoxyribose
  • Catalysed by DNA Polymerase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why does the DNA need to be single stranded in DNA Replication?

A
  • Each strand acts as a template
  • Determines the order of nucleotides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Contrast the structures of ATP and a nucleotide found in DNA to give two
differences.

A
  • ATP contains ribose whereas DNA contains deoxyribose
  • ATP has 3 phosphate groups, DNA has 1
  • ATP nitrogenous base is adenine whereas DNA is varied
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why can new nucleotides can only be added in a 5’ to 3’
direction.

A
  • DNA is antiparallel
  • DNA Polymerase is specific
  • Can only bind to 5’ end of DNA
  • Shapes of 5’ and 3’ end are different
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe how an ATP molecule is formed from its component molecules.

A
  • Condensation reaction
  • Between adenine, ribose and three phosphate groups
  • Catalysed by ATP Synthase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Explain five properties that make water important for organisms.

A
  • Polar so acts as a metabolite for hydrolysis and condensation reactions
  • Solvent so useful in metabollic reactions
  • High specific heat capacity so buffers changes in temperature
  • High latent heat of vaporisation so provides a cooling effect
  • Cohesive so allow movement of column of water in plants
  • Cohesive so produces surface tension supporting small organisms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the roles of iron ions, sodium ions, and phosphate ions in cells.

A
  • Iron= Haemoglobin transports oxygen around the body
  • Sodium ions= contransport of glucose as sodium ions actively transported out of the ileum epithelial cells, lowering concentration in the cell
  • Phosphate ions= joins adjacent nucleotides together, produce atp, phosphorylates other compounds, making them more reactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the cell wall of plants, fungi and bacteria made of?

A

plants= cellulose
fungi= chitin
bacteria= murein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why may nucleus not be visible under a microscope?

A

it is not stained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the name of the membrane of a vacuole

A

tonoplast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the name of membrane of chloroplast and the cytoplasm of chloroplast

A
  • thylakoid membrane
  • stroma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the name of the membrane of the mitochondria and the cytoplasm

A

-cristae
-mitochondrial matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Give one advantage of viewing a biological specimen using a transmission
electron microscope compared with using a scanning electron microscope.

A
  • higher resolution so can see internal structures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Contrast how an optical microscope and a transmission electron
microscope work and contrast the limitations of their use when studying
cells.

A
  • TEM uses electrons, OP uses light
  • TEM has greater resolution so can see smaller organelles under microscope
  • TEM can only see dead specimen, OP can view living
  • TEM cant show colour, OP can
  • TEM is a more complex procedure OP isnt
  • TEM needs thinner specimen
  • TEM focuses using magnets, OP uses glass lens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Name two structures in a eukaryotic cell that cannot be identified using an
optical microscope.

A
  • Mitochondria
    -Ribosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe how you could make a temporary mount of a piece of plant tissue
to observe the position of starch grains in the cells when using an optical
(light) microscope.

A
  • Add a drop of water to the glass slide
  • Obtain a thin slice of tissue and place flat on slide
  • Stain with iodine in potassium iodide
  • Gently lower coverslip with mounted needle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Describe binary fission in bacteria

A
  • Circular DNA replicates
  • Plasmid replicates
  • Cytoplasm divides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the difference between diploid and haploid

A

diploid= double chromosomes so 2 complete sets of chromosomes (2n)
haploid= one set of chromosome (n)

30
Q

How to monitor temperature in an experiment?

A
  • take readings during the experiment using a digital thermometer
31
Q

How does cotransport of sodium and h+ ions work?

A
  • Using ATP
  • Sodium ion and proton bind to the protein
  • Protein changes shape
32
Q

How is virus replicated?

A
  • Attachment protein bind to specific and complementary receptor on Th cell
  • Capsid released into cell and RNA released into cell
  • Reverse transcriptase converts RNA into DNA
  • DNA inserted in to host DNA
  • Hosts organelles used to produce viral proteins
  • Virus assembled and released from cell
33
Q

Previously, the viruses infected only one species of frog. Suggest and explain how the viruses became able to infect other species
of frog.

A
  • Mutation in the base sequence of DNA
  • Altering the tertiary structure of the protein so changing shape of attachment protein so its more complementary
34
Q

What is a monoclonal antibody?

A

Antibodies secreted from cloned B cells

35
Q

What is an antigen?

A
  • Foreign cell
  • Stimulates an immune response
36
Q

What is an antibody?

A
  • Protein specific to antigen
  • Produced by plasma cells
37
Q

Explain how the counter-current principle allows efficient oxygen uptake in
the fish gas exchange system:

A
  • Blood and water flow in opposite directions
  • Maintains concentration gradient of oxygen along entire length of fish
  • Diffusion occurs along entire length of lamellae
38
Q

Describe and explain the mechanism that causes lungs to fill with air:

A
  • Diaphragm contracts and external intercostal muscles contract
  • Rib moves up and out
  • Increases volume and decreases pressure in thoracic cavity
  • So air moves down pressure gradient into the lungs
39
Q

Suggest and explain one way the leaf growth of xerophytic plants would be
different from the leaf growth of sunflowers.

A
  • Xerophytic have slower growth
  • Lower number of stomata for gas exchange
40
Q

Use your knowledge of gas exchange in leaves to explain why plants
grown in soil with very little water grow only slowly.

A
  • As very little water, stomata close to conserve water
  • Less carbon dioxide taken in so less respiration for growth
41
Q

Explain three ways in which an insect’s tracheal system is adapted for
efficient gas exchange

A
  • Tracheoles are thin so short diffusion distance
  • Tracheoles are branched so increased surface area for diffusion
  • Tracheoles have fluid at end which moves into tissues during exercise so faster diffusion through air to the gas exchange surface
42
Q

Describe the processes involved in the absorption and transport of
digested lipid molecules from the ileum into lymph vessels

A
  • Micelles contain bile salts and fatty acids
  • Make monoglycerides more soluble in water
  • Fatty acids and monoglycerides absorbed by diffusion
  • Reform into triglycerides by smooth endoplasmic reticulum
  • Vesicles move to cell membrane by exocytosis
43
Q

Describe the role of micelles in the absorption of fats into the cells lining
the ileum.

A
  • Micelles contain bile salts and fatty acids
  • Micelles make fatty acids more soluble in water
  • Fatty acids absorbed by diffusion
44
Q

How is golgi involved in absorbing lipids

A
  • Modifies triglycerides
  • Combines triglycerides with proteins
  • Packaged for release
45
Q

Explain how water from tissue fluid is returned to the circulatory system.

A
  • Plasma proteins remain in the blood
  • Water potential decreases in the blood
  • Water diffuses into the blood by osmosis
  • Water returns to the blood by lymphatic system
46
Q

How do arteries maintain blood flow?

A
  • Elastic recoil due to muscle
  • Maintain blood flow
47
Q

Binding of one molecule of oxygen to haemoglobin makes it easier for a
second oxygen molecule to bind.

A
  • Binding of first oxygen changes tertiary structure of haemoglobin
  • Uncovers another binding site so easier to bind
48
Q

Describe the cohesion-tension theory of water transport in the xylem.

A
  • Water evaporates due to transpiration
  • Decreased water potential in the leaf
  • Water drawn up via xylem, creating tension
  • Cohesive nature of water and hydrogen bonding between water molecules creates continuous column of water
  • Adhesion of water to xylem walls
49
Q

Describe the mass flow hypothesis for the mechanism of translocation in
plants

A
  • Sucrose is actively transported into phloem sieve tube elements
  • Via companion cells and ATP
  • This decreases the water potential in the sieve tube elements
  • Water diffuses into the phloem via the xylem by osmosis
  • This increases the hydrostatic pressure in the phloem so causes mass flow of sucrose solution from source to sink
  • At roots, sucrose used for respiration or stored
50
Q

Describe how a gene is a code for the production of a polypeptide

A
  • Base sequence
  • Of triplets
  • Determines the base sequence of amino acids in polypeptide
51
Q

What is an exon

A
  • Base sequence or triplet which codes for the base sequence of amino acids and rRNA
52
Q

Define ‘non-coding base sequences’ and describe where the non-coding
multiple repeats are positioned in the genome.

A
  • DNA which does not code for a polypeptide
  • Found between genes
53
Q

Suggest one way the structure of the chromosome could differ along its
length to result in the stain binding more in some areas.

A
  • Difference in base sequences
54
Q

What is a homologous pair of chromosomes?

A

2 chromosomes which carry the same genes

55
Q

Describe differences between tRNA and mRNA

A
  • tRNA is clover leaf shaped, mRNA is linear
  • tRNA has hydrogen bonding, mRNA doesn’t
  • tRNA has an amino acid binding site, mRNA doesn’r
  • tRNA has an anticodon, mRNA has a codon
56
Q

Describe how a polypeptide is formed by translation of mRNA.

A
  • mRNA attaches to ribosome
  • ribosome moves to start codon
  • tRNA anticodon binds to complementary codon on mRNA
  • tRNA brings specific amino acid with it
  • Amino acids join via condensation reaction forming peptide bond using ATP
  • ribsome ‘fits’ around 2 codons
  • tRNA released after amino acids bind
  • Ribosome moves along mRNA to form polypeptide until stop codon reached
57
Q

Give the two types of molecule from which a ribosome is made.

A
  • rRNA
  • protein
58
Q

Describe the process of crossing over and explain how it increases genetic
diversity

A
  • Homologous pairs of chromosomes associate forming a bivalent
  • Chiasmata form
  • Equal lengths of alleles are exchanged
  • Forming a new combination of alleles
59
Q

What is species richness?

A
  • Number of different species in a community
60
Q

What is index of diversity

A
  • Abundance of each species
61
Q

Why is index of diversity more useful than species richness?

A
  • IOD measures abundance of each species
  • May be more of one species
62
Q

Give ways in which sampling procedure can be standardised

A
  • Same sampling time
  • Same time of day of samples
  • Same size of area sampled
63
Q

Give two ways the students would have ensured their index of diversity
was representative of each habitat.

A
  • Random sampling
  • Large sample size
64
Q

What is a species

A
  • group of organisms that can reproduce to form fertile offspring
65
Q

What is a hierarchy?

A
  • smaller groups within larger groups
  • With no overlap
66
Q

What are 4 things scientists can compare to determine genetic diversity

A
  • Base sequence of amino acids
  • Base sequence of DNA
  • Base sequence of mRNA
  • Compare features
67
Q

suggest two reasons why populations might show very
low levels of genetic diversity.

A
  • Population may have been very small/ genetic bottleneck
  • Population may have started off small/ founder effect
68
Q

what is meant by genetic diversity?

A
  • number of different alleles in a gene
69
Q

where does transcription occur in a eukaryotic cell

A

nucleus

70
Q
A

A level Bio (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions