Biology P2 Flashcards
Difference between population and community
Population is all of the same species in the habitat and community is the populations of all the different species in the habitat
Peat bogs
4 Ways land is used by humans
Farming
Quarrying
waste disposal
Building
What is accomodation
Eye lens changing shape to focus image in retina
Describe the path of stimuli to response in a reflex
Stimulus—receptor—sensory neuron—CNS—motor neuron—effector response
What is myopia and hyperopia
Hyperopia is long sightedness so they cant focus on near things (can only focus on long stuff)and the light focuses too past the eye
uses convex lens
Myopia is short sightedness so they cant focus on far objects(can only focus on close stuff) and the light focuses too early on the eye uses concave lens
Describe how the eye focuses on near and far objects
For far objects the light needs less magnification (the line form the top and bottom of the object are almost parallel assume object is smaller than eye)so the lens needs to be flatter, the suspensory ligaments tighten and the muscles relax
For near objects the light needs more bending(the line from the top and bottom need to be bent a lot assume object is bigger than eye) so lens needs to be rounder, the suspensory ligament are loose and the ciliary muscles tight
Describe decay RP
Set amount of milk with an indicator(methyl orange) in a test tube and set amount of lipase enzyme in another test tube place both in water bath until same temp as the water
Mix together with glass rod and start timer
When colour changes it means that the milk is acidic because of the lipase turning lipids into fatty acids showing decay stop timer
Repeat for different temps to get different times showing how rate of decay changes with temp
CV: Amount of each substance
What is a specific gene responsible for
Create a protien
Different ways to study brain
Study patients with brain damage to see what effect the damaged section has on the patient
Electrically stimulate brain using small electrodes and see what effect the stimulation has on
MRI scans place patients in MRI while they perform actions and you can see what part of the brain are active during
Label eye https://imgur.com/a/VjeeRbV
https://imgur.com/a/VjeeRbV
How does eye adjust for brightness
If to bright circular muscles contract and radial muscles relax making the pupil smaller reducing amount of light getting into the eye so it doesn’t get damaged
If to dim the circular muscles relax and radial muscles contract increasing pupil size letting more light through
Tip to remember
radial muscle goes in a straight line against the circular motion so if it contracts it make the iris thinner by pulling it like a curtain
Different treatments for vision defects
Laser eye surgery cornea shape changed using laser so cornea bends light more strongly or weakly
Contact lenses thin lenses on eye that bends the light to correct for fault in focusing
Lens replacement lens in eye is surgically removed and replaced by artificial one
Different things homeostasis is used for
Water level
Blood glucose level
Temperature
How does homeostasis work
Receptor cells detect stimuli (lack of glucose in blood) goes to a coordinate centre where an effector to have a response (a muscle contracting a gland releasing a hormone)
What is the endocrine system and example of glands
Instead of nervous system endocrine where glands and hormone are used to send messages.
Examples are Pituitary gland master gland controls body conditions and other glands
Thyroid gland produces thyroxin controls metabolism rate ,growth and temperature
Adrenal gland above kidney releases adrenaline for fight or flight response
Pancreases controls blood glucose level releases glucagon and insulin
Ovaries produces oestrogen controls menstrual cycle
Testes produces testosterone controls puberty and reproduction
How is blood glucose level controlled
Carbohydrate that is eaten gets turned into glucose increasing blood sugar level
Glucose is used in cells for respiration if too much, insulin is produced by pancreases which makes the liver turn glucose into glycogen which is stored in the liver and muscles
If glucose to low glucagon is released by pancreas which make the liver turn glycogen into glucose increasing blood sugar level
Different types of diabetes Diabetes
Type 1 Pancreas doesn’t produce enough or no insulin so blood glucose level becomes too high. Can be fixed with insulin injection when blood glucose level is too high. Can also be treated with regular exercise and limiting intake of simple carbohydrates
Type 2 cells don’t respond to insulin so blood glucose levels increases. Obesity can increase chances of developing type 2. Can be controlled with regular exercise and controlled carbohydrate diet.
How is temperature controlled
Too hot so sweat glands produce sweat that cools you down by evaporating, vasodilation blood vessels dilate so blood flows closer to the skin to transfer more heat to the environment
Too cold vasoconstriction blood vessels thinner to limit the amount of energy transferred to the environment, muscles shiver to release energy as heat , hair stands up to create insulated layer of air around skin
What is deamination
Excess amino acids from proteins cant be stored so the liver breaks down amino acids producing ammonia. That is deamination. Ammonia is toxic so the liver breaks that down into harmless urea
How do the kidneys work
Blood containing excesses water ions and urea passes through the kidney. Water, ions , urea, glucose are filtered out through a semi permeable membrane(called filtration) then all the glucose some water and some ions are absorbed back into the blood(selective reabsorption)
Why is it important to have the right amount of water and ions in blood
Need the right water level for blood other wise if too concentrated will draw water out by osmosis from cells and if too dilute water enters cells through osmosis causing the cells to not work as efficiently
How is ADH used
Used in controlling blood water level released by pituitary gland
The amount of ADH released affects how much water is selectively reabsorbed back into the blood so if water level is too high in blood less ADH is released so less water gets selectively reabsorbed until water level gets too low and and more ADH is released to selectively reabsorb more water into the blood
How does dialysis work
Can use a dialysis machine where the patients blood gets pumped past partially permeable membranes that only allows glucose, water , urea ,ions to pass through. On the other side of the walls is dialysis fluid which contains the right amount of water ions glucose and no urea concentration as healthy blood meaning that excess water and ions and all of urea will diffuse from the blood until it is at the same level as dialysis fluid and therefore healthy blood. Have to do this a couple times a week for a few hours and can cause blood clots and infection
Advantages and disadvantages of kidney transplant verses dialysis
Shortage of kidneys while dialysis machines are readily available
Dialysis requires regular visits and long hours of treatment while kidneys can lead a normal life
Dialysis machine expensive in the long run while kidney transplant only initially expensive
Kidney transplant you might need to take immune suppressants
Dialysis could lead to infections and blood clots
Give stages of the cylce
1)lining breaks down Day 1-4
2)Lining builds back up Day 4-14
3)Egg is released and lining maintained Day 14-28
4)Back to one
Describe what the different fertility hormones do
FSH
Pituitary gland
Cause egg to mature
Stimulates Oestrogen
Oestrogen
Ovaries
Builds up lining
Stimulates LH(starts egg release) , Prohibits FSH(stops egg form maturing cause already released)
LH
Pituitary gland
Releases egg
Progesterone
Ovaries
Maintains lining (without lining breaks)
Inhibits LH and FSH (stops egg from maturing and releasing)
Different ways to control fertility
Can use hormones in form of pill , contraceptive patch, contraceptive injection, contraceptive implant and IUD they release progesterone and oestrogen. The progesterone produces thick mucus that traps the sperm and oestrogen that stops the egg from releasing the hormones are 99% effective. The IUD also kills sperm and stops egg from implanting in the walls of the uterus
Can also use barrier method that stop the sperm from meeting the egg
Can use condoms that also prevent STDs
Can use a diaphragm that goes over the cervix and spermicide that kills the sperm
Can also use just spermicide but it isn’t very effective
Can also use sterilisation that cuts the fallopian tube and vasectomy that cuts the sperm duct
Can use rhythm method to have sex when women is least fertile during the cycle but isn’t very effective
Can also do abstinence where no sex takes place
What can be done to help infertility
Women with low levels of FSH can be given FSH and LH to help more eggs to mature and release increasing the chance of pregnancy
But it doesn’t always work and might need multiple attempts and can cause multiple pregnancy and twins
If they cant get pregnant using hormones they can use IVF
The women is given FSH and LH to release multiple eggs the eggs are collected and are fertilised using sperm in a lab. The egg is then grown into an embryo and a then some of the cells are transferred to the women’s uterus.
It can help infertile couples to have a child but it can be stressful because of the low success rate and expensive. It could also lead to multiple births if the cells split and each grow into a child.
What is phototropism
In shoots auxin is produced and accumulate on the side that isn’t exposed to sunlight it promotes growth in shoots so the shaded side faster making the stem bend towards the light(phototropism)
What is gravitropism
In roots auxin gathers on the under side of the roots because of gravity and it inhibits growth causing the roots to bend down wards in shoots it gathers on the underside and causes the underside to grow quicker making the shoot bend away from the ground
Different plant hormones and what they do
Auxin controls plant growth
Gibberellin controls germination and stem growth
Ethene stimulates fruit ripening
Uses of plant hormones
Uses
Auxin can be used as weed killer whilst having no affect on grass
Can be used as rooting powder to help cuttings grow roots. Can also be used to grow cells in tissue culture
Gerbilline can be used to control seed dormancy, to make plants induce flowers, to grow bigger fruits
Ethene can be used to ripen fruits when needed, fruits can be picked when unripe and transported then ripened using ethene at it’s destination
Structure of DNA
Phosphate sugar backbone with a base attached. One nucleotide is 1 phosphate 1 sugar and 1 base. The bases are A T and C G
What is mRNA
Since the DNA cant move outside the nucleus mRNA is used to copy the a section of the DNA and takes it to ribosomes for it to make it is the messenger between the two
Uses of protiens
Once the amino acids have been assembled together it folds into a unique shape that is the protein, the unique shape can be used as
Enzymes
Structural Proteins(ligament, cartilage)
Hormones
Different types of mutation
Insertion
Extra base is inserted and effect how all other genes down the line are read
Deletion
A base is deleted effects how all other genes are read down the line
Substitution
A base is swapped for another base
Organisms that reproduce asexually and sexually
Malaria reproduces sexually in mosquito but asexually in host
Some plants reproduce sexually using pollen but also asexually with runners in strawberry’s and bulbs that form from the main bulb and divide off
Fungi produce spores to reproduce the spores can be sexual and asexual
What is an alleles
different form of gene for a characteristic
What is phenotype
organisms outward appearance
what is genotype
the combination of alleles in an organism
What is a carrier
Some one that has one dominant allele and one recessive allele so don’t have the phenotype of the recessive but still carry the gene
What is cystic fibrosis
Genetic disorder of cell membrane causes them to produce excess mucus in air passages. Caused by recessive allele
What is embryonic screening and what are the pros and cons
During IVF or a pregnancy a cell can be removed for its DNA to be tested for different genetic disorders if any disorders are found the IVF embryo is destroyed and the pregnancy terminated
Con
Could go too far and people start choosing desirable embryos based of characteristics
People with genetic disorder should still have the right to live
Screening is expensive
Pro
Get rid of suffering for people
Cost less money overall for government and tax payers
Who is Mendel and what did he discover
Monk that bread pea plants with different characteristics together and then bread the off springs together concluded that hereditary units are passed down from the parents one from each parent.
The hereditary unit can be recessive or dominant where only the dominant will show
Different type of variation
Genetic variation
the combining of parents gametes causes genetic variation so no two of the species are the same
Environmental variation
Conditions the organism lives in e.g. plenty of sunlight, lack of food
These together affect the organisms characteristics
How does mutations lead to variation
Mutations change DNA sequence which could rarely have an effect on the protein made and the change protein can rarely have an effect on the organisms phenotype
If the environment changes and the different phenotype makes the organism more suited then the phenotype gets passed down to off spring through natural selection
Describe survival of the fittest
Organisms had wide range of characteristics and had to compete for resources the ones that where more suited survived and so were more likely to reproduce and pass on the gene to offspring
Overtime the species changes because of this and evolves
What could cause extinction of a species
Environment changes too quickly
Catastrophic event
Gets out competed by competition for resources
New predator is introduces
New dieses kills them
Drawbacks of selective breeding
Reduces gene pool as number of different allele in species becomes less because of inbreeding between the best animals
Causes genetic disorders to be inherited between them
And if a new dieses appears the lack of variation could cause there to be no resistant allele
Who is Lamarck
alternate theory of evolution
How is genetic engineering carried out
Gene that is wanted is isolated from the rest of the genome using enzymes
The gene is then placed in side a bacteria plasmid or a virus
these are used as vectors to transport the specific gene into the organisms cell
Done in the early stage of the organism so all the replicated cells contain the modified genome
Uses of genetic engineering
Improve crop yield and resistance to dieses, insects, herbicide
Bacteria been genetically modified to produce human insulin
Gene modifications for genetic disorders in humans called gene therapy
Pros and cons of genetic engineering
Con
Don’t know the full effect of eating the GM crop on human health
The transplanted gene could get out into environment and other plants
