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Science > Biology Paper 1 > Flashcards

Biology Paper 1 Flashcards

1
Q

Describe how an impulse passes from the relay neurone to the motor neurone

A
  • the impulse in the relay
    neurone triggers the release
    of a chemical
  • neurotransmitter diffuses across synapse
  • new impulse triggered in
    motor neurone
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2
Q

Explain the function of a reflex arc

A
  • a process that occurs in
    response to danger
  • subconscious process
  • protects the body from harm
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3
Q

Explain one way that the spread of tuberculosis (TB) can be reduced or
prevented

A
  • Wear a mask because TB is spread through the air
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4
Q

Explain why people with AIDS are more susceptible to TB

A
  • HIV weakens immune system by decreasing white blood cells
  • Unable to prevent TB pathogen from invading the body
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5
Q

Describe two processes that occur in cells during prophase.

A
  • Identical chromatids are
    joined
  • Nuclear membrane breaks down
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6
Q

State the term used to describe the process which occurs after mitosis, when
the cell divides into two.

A
  • Cytokinesis
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7
Q

Describe how to adjust the microscope to view the slide at a magnification of x400

A
  • use the x40 objective lens
  • use the x10 eye piece lens
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8
Q

Discuss the benefits and risks of using stem cell therapy to treat arthritis

A
  • Stem cells can become specialised
  • reduces symptoms of arthritis
  • stem cells may continue to divide
  • new cells may not function correctly
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9
Q

Describe how cancer develops in the liver

A
  • mutations in DNA
  • cell division is
    uncontrolled
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10
Q

Figure 6 shows the inheritance of haemochromatosis in a family, State and explain the genotype of female Z.

A
  • heterozygous
  • affected offspring inherited recessive allele
  • unaffected offspring inherited dominant allele
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11
Q

Explain why the time taken for the milk to curdle decreases from 30°C to 40°C.

A
  • more chance of collision
    between the chymosin
    and the milk protein
  • due to an increase in kinetic energy from the increasing temperature
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12
Q

Explain what the expected result would be if two drops of chymosin were added to the milk at 70°C in the test tube.

A
  • time taken would be
    longer
  • because the enzyme is
    denatured
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13
Q

Describe two improvements that could be made to the method of this
investigation so that the optimum temperature for chymosin can be found

A
  • use a smaller interval
    between the
    temperatures
  • repeat the test at each
    temperature
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14
Q

Explain how to genetically modify a bacterial cell to produce chymosin

A
  • plasmid is cut with
    restriction enzymes
  • sticky ends are
    complementary which ligase connects with the chymosin gene
  • recombinant plasmid is
    inserted back into the
    bacterial cell
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15
Q

What is the tip of the sperm cell called and used for?

A
  • Acrosome and has enzymes that digest the egg cell membrane
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16
Q

State why ethanol is used in fruit cells practical

A
  • To precipitate the DNA
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17
Q

Compare the outcomes of mitosis and meiosis

A
  • mitosis produces 2 cells and
    meiosis produces 4 cells
  • mitosis produces diploid cells
    and meiosis produces haploid
    cells
  • mitosis produces body cells
    and meiosis produces
    gametes/ sex cells
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18
Q

What is the name of the domain that plants belong to?

A
  • Eukarya
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19
Q

Give a reason why the three domain method of classification has been
suggested

A
  • Improved genetic analysis
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20
Q

Describe three other features of a bacterial cell

A
  • no nucleus
  • cell wall
  • no mitochondria
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21
Q

What is the rate of reaction for 25 beads?

A
  • 25 x 120 = 3000
  • 25/3000 = 0.008
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22
Q

Explain why the same volume of lactose solution was used for each test

A
  • To control a variable
  • Allow results to be compared
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23
Q

Devise a method to find the optimum temperature for the enzyme lactase

A
  • Mix equal volume of lactase with
    equal volume of lactose
  • incubate the tubes at different
    temperatures
  • the temperature
    that produces glucose
    quickest is the
    optimum
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24
Q

Explain why myelination is needed on motor neurones but not on neurones in
the brain

A
  • myelination speeds up impulses
  • motor neurones transmit
    information over a greater distance
    than neurones in the brain
  • neurones in the brain
    connect to other neurones in the
    brain
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25
Q

What is the axon

A
  • Carry impulses away from the cell body
  • the tube that runs along the neurone
26
Q

Describe the role of sensory neurones

A
  • To transmit electrical impulses from the receptors to the brain
27
Q

Explain how impulses are transmitted at synapses

A
  • synapse is a gap between
    neurones
  • electrical impulse stimulates the
    release of chemical
  • neurotransmitter diffuses across the synapse
  • stimulates electrical impulse in the next neurone
28
Q

Explain how a gastric band helps a person to lose weight

A
  • reduces the volume of the
    stomach
  • so it reduces food intake
  • so stored fat is used
    up
29
Q

Explain what the BMI and waist : hip ratio for male A shows about his weight distribution

A
  • Male A weight is distributed evenly around body
  • His BMI shows that he is overweight but his waist:hip ratio shows he is below
    0.9 and is healthy
30
Q

Potato chip A is transferred from the distilled water into a concentrated salt solution. Explain what will happen to the cells in potato chip A

A
  • The cells would get smaller
  • water moves out by
    osmosis
  • from a high concentration of water molecules in the potato to a low concentration of water molecules in the salt solution
31
Q

Describe the possible benefits of embryonic stem cells

A
  • have the potential to produce any
    cell type
  • less chance of patient rejecting their
    own cells
  • used for cell transplants
32
Q

What is the correct order for mitosis

A
  • prophase (chromosones condense/nuclear membrane breaks down), metaphase (align in the centre of dividing cell),
    anaphase (separates each chromatid into a pair of chromosomes and pulls them to opposite ends of the cell),
    telophase (nucleus forms around each set of daughter chromosomes)
33
Q

Describe what happens during interphase (part of cell cycle)

A
  • DNA is replicated
  • production of cell organelles
34
Q

Explain how a magnification of 400 × can be obtained using the lenses on a
light microscope

A
  • 40x objective lens
  • combined with 10x eye piece lens
35
Q

The student decided that the rate for the 25% hydrogen peroxide solution
was not anomalous.

Give the reason why the result was not anomalous.

A
  • all active sites of catalase were occupied
36
Q

What is the pentagon in a DNA nucleotide

A
  • sugar
37
Q

Describe how these changes in DNA sequence can affect the individuals and how sequencing a person’s genome could influence their medical treatments.

A
  • DNA has 4 different bases
  • changes in the DNA are mutations
  • identify genetic diseases
  • allow the individual to modify their lifestyle to reduce
    risk
  • take preventative medicine
  • we have a better understanding of some diseases
  • provides opportunity for personalised medicines
38
Q

Which type of cell is destroyed by the HIV virus?

A
  • White blood cell
39
Q

Give one reason why countries reporting the number of people diagnosed with measles per million of the population is better

A
  • allows comparisons to be
    made between countries
40
Q

Give one reason why the number of people per million diagnosed with
measles is different in these countries

A
  • vaccination
41
Q

Describe how the student would prepare a microscope slide using these cells

A
  • use a thin section of
    cells
  • add a stain
  • place a cover slip on top of
    the sample
42
Q

State the term used to describe a change in the sequence of DNA bases

A
  • mutation
43
Q

Explain how natural selection could have caused an increase in beak length
because of the use of bird feeders

A
  • the population of great tits
    shows variation
  • bird feeders provide a selection
    pressure
  • survival of the fittest
  • birds with longer beaks can get more food
44
Q

Why are the cells from birds described as eukaryotic?

A
  • they have membrane-bound organelles
45
Q

Both students also included a tube containing 10cm3 of starch solution with 5cm3 of distilled water instead of 5cm3
of amylase solution. They tested the solution for starch and for glucose every 30 seconds.
Give one reason why this tube was included in their investigations.

A
  • it is a control to check that starch
    doesn’t breakdown into glucose
    without amylase
46
Q

Devise a method the students could use to confirm the optimum pH for amylase

A
  • mix starch solution with
    amylase
  • use different pH values
  • control named variables
  • a method of testing for
    glucose
47
Q

How does a sensory neurone look like

A
  • has cell body at the centre
48
Q

Describe the evidence that scientists might have used to show that
Ardipithecus ramidus inhabited the Earth earlier than Homo habilis

A
  • scientists might look for differences in the structural features of the fossil
  • Ardipithecus ramidus would be deeper in the rock layer than Homo habilis
49
Q

Suggest an explanation for the extinction of Homo habilis

A
  • likely to be out-competed by Homo erectus
  • due to the presence of a new selection
    pressure
50
Q

Describe how drought-resistant crop plants can be produced

A
  • genetic variation means that some plants will be tolerant of drought conditions and these can be selected
  • cross-pollinate these plants and grow the seeds under drought conditions
  • select offspring and repeat over several generations
51
Q

Which statement gives a reason why dieting can be used to reduce weight in
obese people?

A
  • Dieting reduces energy consumption
52
Q

Give one way that the student could obtain more data to increase the
accuracy of point Q

A
  • Repeat the test using intermediate concentrations between 0.2 and 0.4 mol dm−3
53
Q

Which of the following is a correct description of a process involving the transport of molecules?

A
  • Active transport is used to obtain molecules in a low concentration environment
54
Q

State the genotype of Rani

A

heterozygous

55
Q

Explain how two parents with a dominant phenotype can produce offspring expressing a recessive characteristic

A
  • both parents must be heterozygous for the recessive allele
  • so the offspring must inherit the recessive allele from each parent
56
Q

Explain why phenolphthalein turns colourless when lipase breaks down the
lipids in milk

A
  • fatty acids are formed when the lipids are broken down by
    lipase
  • and fatty acids are acidic so the pH decreases
57
Q

Explain why enzymes can only catalyse specific reactions

A
  • the active site of an enzyme has a specific shape because
    of the order of the amino acids
  • the substrate must have a shape which is complementary to the active site
58
Q

Explain how a stent works to treat cardiovascular disease

A
  • stent inserted into blood vessel and is expanded
  • stent opens and widens blood vessel
  • greater blood flow through blood vessel and more oxygen delivered around body
59
Q

Give reasons why native Americans selectively bred teosinte

A
  • to produce more food
  • to improve quality of food
60
Q

Describe what occurs during anaphase of mitosis

A
  • the chromosomes are split
  • then the chromatids are pulled to either side of the cell
  • by spindle fibres
61
Q

Both tubes were placed in a 5% sucrose solution and left for 1 hour. Explain how and why tube 1 and tube 2 would look different after one hour

A
  • tube 1 will be larger as water will move into the tube by osmosis, from a high water potential outside tube 1 into the low water potential inside tube 1 across the partially permeable membrane of
    the visking tubing
  • tube 2 will shrink as water will move out of the tube by osmosis, moving from a high water potential inside tube 2 to a lower water potential outside of tube 2 across the partially permeable membrane of the visking tubing
62
Q

The bonds joining the two strands of a DNA molecule together are

A
  • weak hydrogen bonds

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