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biology paper 2 > biology paper 2 > Flashcards

biology paper 2 Flashcards

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1
Q

what is homeostasis

A

an organisms ability to regulate/ control its internal conditions so that chemical reactions can occur at an optimum rate

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2
Q

describe the nervous system

A
  1. receptor detects a change due to a stimulus
  2. sensory neurones carry this information from the receptor to the CNS
  3. the CNS sends information to the effector - e.g- muscles along a motor neurone
  4. muscles contract etc.
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3
Q
A
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4
Q

what is a reflex

A
  1. bee stings finger
  2. stimulation of the pain receptor
  3. impulses travel along sensory neurone
  4. impulses are passed along a relay neurone via a synapse
  5. impulses travel along a motor neurone via a synapse
  6. when impulse reaches muscle, it contracts
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5
Q

what does the cerebral cortex do

A

responsible for higher functions:
memory
speech
problem solving

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6
Q

what does the cerebellum do

A

responsible for motor skills:
balance
movement
coordination

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7
Q

what does the medulla oblongata do

A

unconscious actions
heart rate and breathing rate
sends signals to the adrenal glands to release adrenaline

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8
Q

how does the eye focus on objects which are far away

A

-ciliary muscles relax
-suspensory ligaments tighten
-this results in the lens becoming thin
-light is only refracted by a small amount.

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9
Q

how does the eye focus on objects nearby

A
  • ciliary muscles contract
    -suspensory ligaments slacken
    -this results in a thick lens
    -more light is refracted so it converges on the retina
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10
Q

what is the cornea

A

transparent outer layer where light enters the eye

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11
Q

what does the pupil do

A

change size depending on the light intensity

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12
Q

what is the sclera

A

surface that covers the eye

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13
Q

what are the retina cells

A

-rods: detect light intensity
-cones: detect three different colours, red green and blue- wavelengths of light

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14
Q

what is the medical term for short and long sightedness

A

short sighted: myopia - cant focus on far away objects
long sighted: hyperopia - cant focus on objects nearby

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15
Q

what is thermoregulation

A

the body controlling its internal temperature.
the brain detects blood temperature then sends nervous and hormonal signals to effectors

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16
Q

how does thermoregulation work if you are too hot

A
  • sweat glands produce water which evaporates, taking away heat
    -blood vessels dilate: vasodilation- increases blood flow to the skin to increase the rate of heat loss
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17
Q

how does thermoregulation work if you are too cold

A

-hairs stand on edge to trap heat- act as a layer of insulation
-shivering - muscles contracting produce more heat
-blood vessels contract- vasoconstriction

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18
Q

what is the endocrine system

A

a system of glands that secrete hormones to send signals to effectors transported via the blood - slower than the nervous system

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19
Q

describe the endocrine system

A
  1. pituitary gland- ‘master’ gland - sends signals to other glands
  2. pancreas - secretes insulin (and glucagon) to control blood sugar levels
  3. thyroid - controls growth, metabolism
  4. adrenal glands- produce adrenaline
  5. ovaries and testes : ovaries release eggs and secrete hormones, testes produce sperm
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20
Q

what happens when blood glucose levels are too high

A
  • pancreas secretes insulin
    -causes glucose to move from bloodstream into cells to be used for respiration
    -excess glucose is converted into glycogen as an energy store
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21
Q

what happens when blood glucose levels are too low

Study These Flashcards
A

-pancreas secretes glucagon
-this causes liver and muscles to convert glycogen back into glucose
negative feedback

22
Q

what are the types of diabetes

Study These Flashcards
A
  • type 1 diabetes : pancreas cant produce enough insulin - injections needed
  • type 2 diabetes : cells do not absorb enough glucose as they should - caused by obesity
23
Q

what are the types of diabetes

Study These Flashcards
A
  • type 1 diabetes : pancreas cant produce enough insulin - injections needed
  • type 2 diabetes : cells do not absorb enough glucose as they should - caused by obesity
24
Q

how does the body control water levels - nitrogen levels

Study These Flashcards
A
  • water is lost through sweating, exhalation and urinating
  • excess water is removed from the blood by the kidneys to the bladder
    -water is mixed with urea to make urine
    -urea contains ammonia from amino acids from excess proteins broken down in the liver
25
what happens to cells when there is too much water
- water moves into the cell via osmosis - cell becomes turgid and could burst
26
what happens to cells when there is not enough water
-water moves out of the cells via osmosis -cells becomes flaccid
27
how do the kidneys work
ADH is produced from pituitary gland that causes tubules in kidneys to reabsorb more water into the blood stream. if water levels are too high, less ADH is made so more water is sent to the bladder to leave as urine negative feedback
28
what is negative feedback
response to a change is such that the conditions return back to normal
29
what happens if your kidneys are not working properly
dialysis is required : blood is filtered by a machine , if not done urea - ammonia build up will increase too much and be poisonous
30
describe the menstrual cycle
- FSH ( follicle stimulating hormone ) from pituitary gland causes an egg to mature and the ovaries to produce oestrogen - oestrogen - causes uterus lining to thicken and it inhibits the production of FSH so no more eggs mature, also causes the pituitary gland to secrete LH - LH - lutenising hormone- causes an egg to be released which starts to travel to the uterus a sperm cell can then fertilise this -progesterone : secreted by the ovaries and maintains the uterus lining
31
what are the methods of contraception
FSH inhibiting pills - prevents eggs from maturing Condoms: act as barriers so the sperm cant fertilise the egg progesterone injection/ implant : stop eggs from being released IUD (copper coil) : stops egg from embedding in lining - avoiding sex
32
what are gibberellins
plant hormone which induces germination, promotes flowering, increases fruit size
33
what does ethene do
plant hormone causes ripening
34
what are auxins
plant hormone destroyed by sunlight so causes cells on the shaded part of the shoot to grow more quickly. shoot bends towards the sun : phototropism geotropism : grows downwards
35
what is meiosis
process by which gametes are made - genetically different from parent cells - chromosomes in diploid cells (23 pairs) are copied -similar chromosomes pair up and genes are swapped between them -cells divide to produce two diploid cells - these divide again to produce two haploid cells (gametes)
36
what is a genome
the entire genetic code in an organism- stored in DNA - double helix polymer
37
what is a gene
portion of DNA which codes for a protein
38
what is a genotype
an organisms specific genetic code.
39
what is a phenotype
how this code is expressed in physical characteristics
40
what are the bases which match together
A+T C+G
41
what is an allele
different versions of the same gene
42
what are the different types of alleles
Homozygous- two of the same - BB, bb Heterozygous- two different alleles - Bb
43
what is genetic engineering + process
insertion of a gene into an organisms genome so it synthesises a specific protein to achieve a desired characteristic. 1. desired gene is cut from another organisms DNA using an enzyme 2. gene is inserted into a vector - plasmid 3. vector inserts gene into cells of another organism early in development- to be sure it is present in every cell as the organism grows 4. organism develops with desired characteristic due to every cell synthesising that specific protein
44
what are the two methods of plant cloning
cuttings- gardeners take cuttings from good parent plants, then plant these to produce genetically identical copies of the parent plants. these are produced quickly and cheaply and is simpler than tissue culture. tissue culture- a few plant cells are put in a growth medium with hormones and grow into new plants- clones of the parent plant.
45
what are the two methods of animal cloning
- embryo transplants : sperm cells taken from prize bull, egg cells taken from prize cow. the sperm is then used to artificially fertilise an egg cell. the embryo that develops is then split many times (to form clones) before any cells become specialised. these clone embryos can then be implanted into lots of other cows where they grow- genetically identical to eachother, hundreds of offspring can be produced. - adult cell cloning: taking an unfertilised egg and removing the nucleus. the nucleus is then removed from an adult body cell (skin cell) and inserted into the ‘empty’ egg cell. the egg cell is then stimulated by an electric shock, this makes it divide like a normal embryo. the embryo is then implanted into the womb of an adult female, it grows into a genetically identical copy of the orginal adult body cell as it has the same genetic information.
46
what is classification
organising living organisms into groups. proposed in the 1700s by Carl Linnaeus King - Kingdom Phillip - Phylum Came- Class Over - Order For- Family Good- Genus Soup- Species
47
what is domain and what does it consist of
the broad level of classification above kingdom - archaea : primitive bacteria - extremophiles - bacteria : true bacteria - eukaryota : everything else
48
what is interdependence
organisms depending on each-other for survival. when this happens a community is formed
49
what are abiotic and biotic factors with examples
abiotic: non-living factors: light, temperature, soil ph, co2 concentration biotic: the impact of other organisms - living factors : food, predators, prey, pathogens
50
how do you use a quadrat
- place quadrat in random positions in area - use random number generator - count number of chosen organism in each, calculate mean and then multiply by the total area to get estimate for population -moving it along a TRANSECT allows you to observe changes in population density over a distance
51
what is a food chain
shows the direction of biomass transfer between organisms apex predator- at the top of the food chain and have no natural predator

biology paper 2 (1 decks)

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