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--gcse subjects-- > SB6 PAPER 2 > Flashcards

SB6 PAPER 2 Flashcards

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1
Q

Whats photosynthesis? equation?

A

an endothermic
reaction that uses light energy to
react carbon dioxide and
water to produce glucose and oxygen

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2
Q

how are palisade cells near the top of a leaf adapted?

A

they’re packed with chloroplasts allowing a leaf to absorb a great deal of light

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3
Q

stoma open and shut depending on…

A

amount of light

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4
Q

biomass definition…

A

materials in an organism

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5
Q

leaves contain microscopic pores called stomata, stomata…

A

allow co2 to diffuse into the leaf and are opened by specialised guard cells.

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6
Q

in the light water flows into gurad cells making them..
at night, water flows out of guard cells making them…

A

rigid and opens the stoma
lose their rigidity and stoma shuts

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7
Q

whats a limiting factor?

A

factor which prevents a rate increasing

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8
Q

what are the 3 limitng factors of photosynthesis?

A

light - Photosynthesis requires energy
transferred by light. The greater
the light intensity, the more
energy it transfers

c02 - is a reactant of photoS, the more co2 the quicker the rate of phot

temp - enzymes control the rate of photosynthesis and work best when warm.

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9
Q

2 ways root hair cells are adapted?

A

extensions provide a large surface area so water and mineral ions are absorbed quicker
-thin cell walls ensure flow of water is not slowed down

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10
Q

2 ways water can enter a plant root?

A
  1. diffusion , inside plant roots the cws have an open structure allowing water particles to diffuse to the middle of the root
  2. osmosis - cell membranes are semi permeable so water passes into the cytoplasm of root hair cells by osmosis.
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11
Q

inside xylem vessels is an unbroken chain of water whys this?

A

there are weak forces of attraction between the water molecules

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12
Q

describe the steps of transpiration…

A

water is pulled up xylem vessels in the stem as water evapourates from xylem vessels in the leaves
-osmosis

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13
Q

what is transpiration and how does it help a plant?

A

flow of water up the stem and out the leaves in a plant

-keeping leaves cool
-photosynthesis

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14
Q

factors that can affect transpiaration…

A

wind - moves water mol away from stomata
low humidity - little water vapour in the air
higher temps - particles move faster so diffuse faster

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15
Q

how is sucrose transported around the plant by
translocation

A

sucrose is transloacated in the sieve tubes of the phloem tissue

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16
Q

Explain how the structure of a leaf is adapted for
photosynthesis and gas exchange

A
  • epidermis cells form the outer layer of leaves ], holding it togther and protecting the cells inside
    -epidermis is transparent allowing light to pass throigh easily
    -they have a waterproof Waxy cuticle which prevents water loss
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17
Q

how are deciduous winter leaves adapted?
conifers?

A

they loose their leaves preventing water loss when soil may be frozen.

-conifers have needle shaped leaves with a smaller surface area and thicker cuticle. This creates less wind resistance than broad leaves allowing conifers to with stand high winds

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18
Q

what are hormones? amd how are they transported to their target organs?
target organs?

A

chemical messengers that are made in one part of the body and are carried in/by the blood to other parts

organs affected by specific hormones eg bones during growth

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19
Q

describe 6 endocrine glands

A

pituitary - growth hormones, ACTH , FSH, LH
thyroid gland - thyroxine
pancreas = insulin and glucagon
ovaries - oestrogen and progesterone
adrenal glands - adrenalin
testes - releases sex hormone testosterone

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20
Q

desrcibe how endocrine glands communicate with organs around the body.

A

EG release hormones which are transported to their target organs through the blood

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21
Q

metabolic rate?
resting metabolic rate?

A

overall rate at which chemical reactions occur within the body

same but the body is at rest, warm room, long after a meal

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22
Q

what does thyroxine do?

A

affects many different types of cell, causes heart cells to contract more rapidly and strongly and increase the rate at which proteins and carbohydrates r broken down.

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23
Q

the amount of thyroxine produced by the thyroid glands is controlled by hormones released by 2 glands called…

A

TRH - Thyrotropin releasing hormone
TSH - thyroid stimulating hormone

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24
Q

Explain how thyroxine controls metabolic rate as an
example of negative feedback

A

low levels of thyroxine stimulates production of TRH
in hypothalamus
this causes release of TSH from the pituitary gland
TSH acts on the thyroid to produce thyroxine

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25
Q

What are the effects of adrenalin?

A

-increased HEART rate (heart musc cells contr more rapdily)
-diameter of blood vessels widen, increasing blood flow to muscles
- raised blood sugar levels by stimulating the liver to
change glycogen into glucose

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26
Q

what are the target organs for adrenalin?

A

heart, wider blood vessels, liver , narrow blood vessels

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27
Q

what is the menstrual cycle?
what does it prep the body for?

A

a monthly cycle of changes that take place in a womens reproductive system.
fertilisation of an egg cell

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28
Q

-what happens day 1-5 of cycle?
-when menstruation ends? 6-12
-13-15 ..
-16-28

A

-uterus lining breaks down and is lost with unfertilised egg cell.
-uterus lining starts to thicken again.
-ovary releases the egg
-fertalisation leading to pregancy most likely, uterus lining continues to thicken, egg cell carries alone oviduct to uterus

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29
Q

oestrogen and progesterone control the cycle what does oes do?

A

-in first part of cycle oestrogen causes thickening of uterus wall

30
Q

list 3 contraceptive methods.

A

male condom physical barrier, prevents sperm entering vag
-diaphragm or cap, placed over cervix, prevents sperm in vag entering uterus
-hormone pil - releases hormones to prevent ovulation and thickens mucus at cervix making diff for sperm

31
Q

what causes menstruation to begin?

A

A fall in concentration of oestrogen
and progesterone leads to a
breakdown of the thickened uterus
wall, which results in menstruation

32
Q

what hormones control the release of FSH and LH from the pitiutary gland?

A

the concentration of
oes (which increases as egg folicle matures)
pros (rel after ovulation when folicle becomes corpus luteum)

33
Q

describe first part of menstrual cycle using 4 hormones.

A

-FSH and LH from pituitary gland at brain
-low levels of prog allow FSH to be released
-high level of osetorog stimulate release of mor LH

-increasing progesterome inhibits FSH and LH release

34
Q

describe part 2 of menstrual cycle using 4 hormones

A

-(prog) FSH stimulates growth & maturation of egg follicle which causes the release of oestrogen
-(oest) LH triggers ovulation and after the follicle forms into a structure called the corpus luteum, causing the release of progesterone

35
Q

describe part 3 of menstrual cycle using the 4 hormones

A

-increasing oestrogen causes thickening of wall
-prog and oes levels drop which triggers menstruation

36
Q

how does assisted reproductive technology work and give an example.

A

it uses hormones and other techniques to increase the chance of pregnancy
clomifene therapy is useful for women who don’t release eggs during menstrual cycles. Clomifene helps increase fsh and LH in blood

37
Q

during digestion

A

glucose is released from carbohydrates in food and absorbed by small intestines into the blood and into cells

38
Q

how is blood glucose concentrations controlled?

A

as blood glucose concentrations rise, it stimulates certain cells in the pancreas to release the hormone insulin
-insulin causes cells in liver and other organs to take in glucose.

39
Q

when glucose is absorbed by the liver..
(low concs)

A

its converted into GLYCOGEN which is stored in liver cells
-if blood glucose concentrations fall too low GLUCAGON causes liver cells to convert GLYCOGEN back into glucose

40
Q

what is homeostasis?

A

maintaining constant conditions inside the body

41
Q

people with type 1 diabetes…

A

can’t control rising blood glucose concentrations because they’re pancreatic cells which produce insulin have been destroyed by the body’s immune system

42
Q

why is urine the first test for type 1 diabetes?

A

bc when blood glucose concentrations get too high it can then be detected in the urine

43
Q

people with type 1 diabetes have to inject…

A

have to inject insulin into the fat layer below the skin where it can enter blood and cause blood glucose concentrations to fall

44
Q

explain why people with type 1 diabetes must control their blood glucose concentrations with injections of insulin

A

People with type 1 diabetes do not produce insulin
from their pancreas so they must inject the right
amount of insulin at the right times to keep their
blood glucose concentration within safe limits.

45
Q

what is type 2 diabetes?

A

its caused by insulin releasing cells not producing enough insulin OR by target organs not responding properly to the hormone

46
Q

compare the treatment of ppl with type 1 and type 2 diabetes.

A

People with type 1 diabetes must inject
insulin. People with type 2 diabetes may
be able to control its effects by eating
a low-sugar diet and exercising or may
take medication.

47
Q

why are dr concerned about rising obesity in the uk?

A

obesity may be correlated with type 2 diabetes
if obesity increases more ppl will need treatment

48
Q

thermoregulation?

A

control of body temp which keeps the temp of the major organs close to 37 degs

49
Q

what is the hypothalamus ?

A

small part of brain which monitors temp. It recieves info from temp receptors in the dermis of the skin

50
Q

when the hypothalamus detects temps starting to fall below 37 degs it does 3 things:

A
  1. shivering - is when muscles contract and relax rapidly and some of the energy released from cell respiration warms you up.
  2. Contraction of erector muscles
  3. reduction of blood flow near the skin - keeps warm blood deeper inside the body. this reduces the rate of trasnfer of energy to the air by heating
51
Q

when body temps go over 37 degs the hypothalamus detects this and causes sweating….

A

the sweat spreads out as a thin layer on the epidermis where it evaporates
as the sweat evaporates it transfers energy from skin to surroundings to cool down

the hypt also increases blood flow nearer to surface of skin so the blood can transfer energy to the air to cool

52
Q

what is vasoconstriction -
(body gets cold)
and how does it work

A

the narrowing of the blood vessels

this reduces blood flow in capillaries near the surface of the skin and helps reduce energy transfer to surroundings

53
Q

what is vasodilation?
(bodt gets hot)

A

hypotalaus causes bv to widen
-this increases blood flow through skin capilaries bringing warm blood nearer to skin surface and increase energy trasnfers to surroundings.

54
Q

whats the function of the urinary system?

A

is to remove excess amounts of some substances from the blood including water and mineral salts and products like urea

55
Q

what is urea?

A

urea is produced from the breakdown of excess
amino acids in the liver. carried to kidneys

56
Q

during kidney dialysis…

A

Blood from the patient’s body passes through a
dialysis machine. Substances are exchanged
between the blood and dialysis fluid by diffusion
across the dialysis membrane. This removes
urea and excess substances from the blood before
it is returned to the body.

57
Q

what is another treatment apart from dialysis used kidney failure?

A

organ donation

58
Q

Each kidney is made up of thousands of microscopic tubes called …
urine is made in the..

A

nephrons

59
Q

what is osmoregulation?

A

control of the balance of water and mineral salts in the body

60
Q

what are the first 2 steps of how urine is produced? (Filtration)

A
  1. Blood flows through the glomerulus which runs inside the bowmans capsule of each nephron.
  2. the B.C and Glomerulus let the smaller molecules like water, glucose and urea into the rest of the nephron

the larger molecules like proteins and blood cells stay in the blood.

61
Q

what is P2 of urine being produced ?

A
  1. the filtration fluid flows along the rest of the nephron. Selective reabsorption of useful substances the body needs occurs here, including glucose
  2. These substances r pumped through proteins in the cell membrane in the first convoluted tubule of nephron by AT
62
Q

p3 of urine being produced?

A
  1. Water = reabsorbed by osmosis. This takes place in the loop of Henle and in the collecting duct
  2. At the end of the nephron the remaining fluid flows into ureter. The fluid contains excess water the body dont need, plus urea and other substances .

Now u got urine

63
Q

list one way as to how the nephron is adapted for reabsorbtion of substnces.

A

they have a large surface area between the nephron and capilaries

64
Q

as well as getting rid of urea the kidneys also help control…

A

water content in blood

65
Q

when the pituitary gland detects theres too little water in the blood what happens? (kidneys)

A

it releases the hormone ADH which changes the permeability of the collecting duct in nephrons, increasing urin conc

66
Q

if the collecting duct is permeable….
when theres plenty of water in blood the piturairy gland..

A

water is absorbed by osmosis from CL back in blood
stops releasing ADH

67
Q

what is positive phototropism? and whats it caused by
plants respond to stimuli using…

A

a tropism towards a stimulus , auxins
plant hormones

68
Q

how do auxins cause plant shoots to grow towards light?

A

if shoots are grown with light coming from one direction, auxins move to the shaded side of the root, making cells on the shaded side elongate more causing the shoots to grow towards the light.

69
Q

in roots auxins cause cells ..

A

to stop elongating which causes positive gravitropism

70
Q

what is positive graphitropism

A

growth towards the centre of gravity

71
Q

what are plant gibberellins ?
ethene gas?

A

plant hormones that help seeds germinate and grow shoots and roots

plants hormone that helps fruit to ripen

72
Q

how may selective weedkiller be useful?
rooting powder?
auxins …

A

they kill plants with broad leaves, eg weeds . but not those with narrow leaves like grass
auxins are found in rooting powder; auxins cause plant cuttings develop roots quickly
cause elogation of cells

--gcse subjects-- (11 decks)

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