Paper 2 To Learn Flashcards
(29 cards)
Why would a drug for pain receptors be injected directly into the cerebrospinal fluid rather than as a pill
-rapidly reaches spinal chord
-pill to large to absorb
-broken down by stomach Hydrochloric acid
When recording intensity of pain why is it important to use a statistically valid scale
-Pain tolerance is subjective
-To ensure that differences (in pain detection) were (statistically) significant for a valid comparison
Why would soil be sterilised before growth?
To remove
-pathogen
-pests
-competition
-saprobiants (nitrogen-fixing bacteria)
During an experiment seeing how volume of water affects growth why should soil contain the recommended amount of fertiliser?
-so water is the only variable being measured
-so ph of soil is not affected
-provide usual soil/farming conditions
How does colour vision allow orange to be seen?
Colour vision involves cone cells located in fovea on retina at back of eye
Photoreceptors contain pigments that absorb different wavelengths of light
Greater absorption by red-sensitive photoreceptors
More impulses sent to brain along optic nerve
Different processes leading to evolution of two species of one plant
Allopatric speciation
- geographical isolation
- Allopatric spectated due to the isolation / separation
- different selection pressures
- alleles given survival advantage increase in frequency in generations overtime
Sympatric speciation
- both found in similar locations
- variation due to mutation
- mutation leads to reproductive isolation separating gene pools by preventing interbreeding within a population eg. Different courtship
Different selection pressures
features of cells in proximal convoluted tubule to allow rapid re absorption of glucose into the blood
- many microvilli to increase surface area
- many carrier proteins for co-transport
- many mitochondria produce ATP
- many ribosomes to produce Carrier/ channel proteins
Where does ADH bind to in a nephron
Receptors on collecting duct and distal convoluted tubule
Where are receptors found that detect a decrease in blood pressure?
Aorta
Carotid artery
How does the release of ADH affect blood pressure
ADH increases re absorption of water
Increases volume of blood
Increases pressure
Ecosystems support a certain size of a population of a species called the …
Carrying capacity
Populations of different species will form a…
Community
Reasons for low efficiency of energy transfer from secondary consumers to tertiary consumers in an ecosystem
-not all food digested
-not all parts of animal eaten
-excretion
-heat loss from respiration
If P < 0.05 what does this show
- there is a significant difference
- results not due to chance
- reject null hypothesis
How could a sequence of DNA be removed from a DNA sample?
- restriction endonuclease
- cut dna at a specific base sequence
Why is is important to know base sequences in a PCR?
for primers, to produce complementary base sequences
PCR amplification formula
2n
What features allow base sequences to be separated by gel electrophoresis ?
Number of nucleotides / bases
Negative charge
Role of ATP in muscle contraction
- binding of ATP to myosin head breaks actin-myosin cross bridge
- causes myosin head to detach and this moves the head
- this causes actin filaments to move inwards
- ATP used for active transport of calcium ions back into sarcoplasmic reticulum
In sex linked inheritance when an allele is carried on the X chromosome causes a disorder why are males more likely to have the disorder?
Males will only have one allele
Females need two recessive alleles / must be homozygous recessive
Females could be heterozygous and carriers
Codominance
Codominance is a type of inheritance pattern where both alleles in a heterozygous individual are fully and equally expressed.
In genetic crosses, the observed phenotypic ratios obtained in the offspring are often not the same as the expected ratios. Explain why
- small sample size
- random fusion of gametes
- linked genes
- Epistasis
Explain why there is a wide variation in the patterns of repeated, non-coding sequences (VNTRs).
VNTRs are non-coding.
This means that a change in the number of repeats does not have any impact on an organism’s phenotype.
As a result, natural selection does not act on variation in the number of repeats in VNTRs.
Individuals with all patterns of repeats pass them on to their offspring and mutation leads to even more new variations.
During electrophoresis why are bands transferred to membrane / paper?
Agarose gel is not very durable
Risk of bands becoming damaged
Transferal preserves them
