Biology Paper 1 Flashcards
Describe how an impulse passes from the relay neurone to the motor neurone
- the impulse in the relay
neurone triggers the release
of a chemical - neurotransmitter diffuses across synapse
- new impulse triggered in
motor neurone
Explain the function of a reflex arc
- a process that occurs in
response to danger - subconscious process
- protects the body from harm
Explain one way that the spread of tuberculosis (TB) can be reduced or
prevented
- Wear a mask because TB is spread through the air
Explain why people with AIDS are more susceptible to TB
- HIV weakens immune system by decreasing white blood cells
- Unable to prevent TB pathogen from invading the body
Describe two processes that occur in cells during prophase.
- Identical chromatids are
joined - Nuclear membrane breaks down
State the term used to describe the process which occurs after mitosis, when
the cell divides into two.
- Cytokinesis
Describe how to adjust the microscope to view the slide at a magnification of x400
- use the x40 objective lens
- use the x10 eye piece lens
Discuss the benefits and risks of using stem cell therapy to treat arthritis
- Stem cells can become specialised
- reduces symptoms of arthritis
- stem cells may continue to divide
- new cells may not function correctly
Describe how cancer develops in the liver
- mutations in DNA
- cell division is
uncontrolled
Figure 6 shows the inheritance of haemochromatosis in a family, State and explain the genotype of female Z.
- heterozygous
- affected offspring inherited recessive allele
- unaffected offspring inherited dominant allele
Explain why the time taken for the milk to curdle decreases from 30°C to 40°C.
- more chance of collision
between the chymosin
and the milk protein - due to an increase in kinetic energy from the increasing temperature
Explain what the expected result would be if two drops of chymosin were added to the milk at 70°C in the test tube.
- time taken would be
longer - because the enzyme is
denatured
Describe two improvements that could be made to the method of this
investigation so that the optimum temperature for chymosin can be found
- use a smaller interval
between the
temperatures - repeat the test at each
temperature
Explain how to genetically modify a bacterial cell to produce chymosin
- 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
What is the tip of the sperm cell called and used for?
- Acrosome and has enzymes that digest the egg cell membrane
State why ethanol is used in fruit cells practical
- To precipitate the DNA
Compare the outcomes of mitosis and meiosis
- 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
What is the name of the domain that plants belong to?
- Eukarya
Give a reason why the three domain method of classification has been
suggested
- Improved genetic analysis
Describe three other features of a bacterial cell
- no nucleus
- cell wall
- no mitochondria
What is the rate of reaction for 25 beads?
- 25 x 120 = 3000
- 25/3000 = 0.008
Explain why the same volume of lactose solution was used for each test
- To control a variable
- Allow results to be compared
Devise a method to find the optimum temperature for the enzyme lactase
- 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
Explain why myelination is needed on motor neurones but not on neurones in
the brain
- 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