Paper 2 Flashcards
Which statement about cellulose molecules is correct?
Branched polymers
Contain alpha glucose
Bonded to eachother by h bonds
Contain 1,6 glycosidic bonds
Bonded to eachother by hydrogen bonds
What relates to calcium pectate?
Found in the middle lamellar, and hold the cell walls together
How do the interactions between auxins and cytokinins could have produced the results shown in the diagram
Removing tip? Removing meristem and absence of auxin- results in lateral shoot growth.
Because auxins inhibits lateral shoot growth
Cytokinins stimulates lateral bud growth
Auxins represses and inhibits and is dominant over cytokinins action
Where is the breathing rate region on the brain?
Below near the spine
Where is the control of balance region on the brain
Part behind the spine
Where is the temperature regulation region on the brain?
Small part near the middle front
What is the state of ion channels during the depolarisation?
Na+ is open and k+ is closed
Describe how exercise results in an increase heart rate
Exercise increases CO2 in the blood, aswell as lowers pH, and increases H+
Detected by chemoreceptors in the aortic body
Impulses sent to medulla
Impulses along shmpathetic nervous system
Noradrenaline is released onto the SAnode
In flowering plants, what are the correct nuclei descriptions?
Zygote nucleus- diploid
Endosperm nucleus- Triploid
Pollen tube- haploid
How do you calculate the mean length of a pollen tube from added chemicals
Read from the graph
Multiplied by the mean length of the pollen tube beofre added chemical
What effect do chemical have on pollen tubes?
Roles of transcription and translation in pollen tube growth
If length is consistent, then the chemical stops transcription and has less effect and smaller reduction on the pollen tube growth
If mean length decreases, pollen tube growth requires production of new proteins and enzymes
Where abouts is the bipolar cell?
Long cell between the others
Where is the cone cell?
After the bipolar cell on the right
Where is the rod cell?
Right st the end on the right
Which direction does the light pass through the retina?
From the cells towards the rod cell
Why does a higher light intensity required to produce an action potential in a cell closer to rod cell than one further away?
Ore rod cells connect to bipolar cell.
Therefore summation occurs regional convergence and add together several generator potentials
So threshold potential and depolarisation occurs in bipolar cell
Rods have more pigments than cones, rhodopsin is very sensitive to light
How candiagrams show that blindness is chased by a recessive allele?
Have to show that the males are colour blind and their chromosome is from their mother. None of the parents are colour kind and therefore must be heterogenous
How do you work out the probability of another child having colour blindness?
Show the genotypes and the offspring genotypes, and then show the ratio and the percentage of probability
Describe the sequence of events that lead to an excitatory postsynaptic potential in the postsynmaptic neurone after stimulation of a neurone
Arrival of action potential at presynaptic terminal.
Calcium channels open and calcium ions enter
Vesicles move to presynaptic membrane
Acetylcholine diffuses across the cleft and synapse
Binding to receptors on postsynaptic membrane, opening na channels etc
What is the action of nicotine on a postsynaptic neurone
Excitatory
What action is lidocaine on a postsynaptic neurone?
Inhibitory
What is the action of cobra venom on postsynaptic neurone
Inhibitory
What is the effect of intensity of stimulation on the production of an action potential in the postsynaptic neurone?
Action potential only occurs when threshold is reached. Due to the levels of acetylcholine are high and the levels of glutamate are low.
An action potential doesn’t occur when levels of glutamate are high
Movement of chloride ions cause hyperpolarisation
How do you Calculate the maximum diameter
Correct calculation of magnification
Eg if measured in um, have to x10000
Correct calculation of diameter: measure the length with a ruler and divide it by 10000 to get it in the right unit
Describe the role of the Golgi apparatus is producing secreted enzymes
Vesicles containing protein from rER move to the Golgi
Proteins are modified and lipids are attached
The proteins leave the Golgi in vesicles
Vesicles fuse with the cell membrane
Explain the effects of calcium ion conc on the rate of intake of alciuim ions through pancreatic cellmembrane
Rate of diffusion increases due to increased diffusion gradient.
Rate of uptake Keele off as calcium ion channels limit rate
Because calcium ipms enter by facilitated diffusion
How are new combinations of alleles produced in meiosis?
Independent assortment of chromosomes. Crossing over and chiasmata formation between homogenous chromosomes
Compare and contract stabilising selection with disruptive selection
Both change frequency of alleles and change genetic diversity
Both select against less well adapted phenotypes
Disruptive deletion selects against phenotypes by stabilising selection selects against extreme phenotypes
Disruptive selection leads to 2 distinct propulsion’s but stabilising selection maintains one population
