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biology gcse > cell biology (paper 1) > Flashcards

cell biology (paper 1) Flashcards

1
Q

what organelle is needed a lot in active transport

A

mitochondria

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2
Q

what does a good blood supply in an exchange surface maintain

A

maintains the concentration gradient

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3
Q

how to calculate the rate of a reaction

A

1000
———
time

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4
Q

what is a catalyst

A

a substance which increases the speed of a reaction without being changed or used up in this reaction

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5
Q

how are villi’s adapted for diffusion

A

huge surface area so digested food is absorbed much more quickly into the blood
they have ;
good blood supply to assist quick absorption
a single layer of surface cells

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6
Q

where are villi’s located

A

small intestine

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7
Q

where does gas exchange happen in the lungs

A

alveoli

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8
Q

what features do exchange surfaces have

A

thin membrane one cell think
large surface area
efficient blood supply - lots of blood vessels

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9
Q

calculation for percentage change in mass

A

final value - original value
——————————————. X100
original value

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10
Q

what substances diffuse through cell membrane

A

oxygen
glucose
amino acids
water

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11
Q

what happens to the rate of diffusion if it is hot

A

gives a faster rate of diffusion because the particles have more energy so move around faster

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12
Q

what happens before mitosis occurs

A

cell has to grow and increase the amount of mitochondria and ribosomes
then duplicates dna

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13
Q

what is differentiation

A

the process by which a cell changes to become specialised

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14
Q

how to convert from millimetres to micrometers

A

X1000

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15
Q

order of mitosis

A

the cell begins to divide

the dna replicates to form two copies of each chromosome

the nuclear membrane breaks down , the chromosomes line up across the centre of the cell

one set of chromosomes is pulled to each end of the cell and the nucleus divides

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16
Q

what is osomois

A

the movement of water from a dilute to a more concentrated solution through a partially permeable membrane

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17
Q

what is a HYPOTONIC solution

A

concentration of solutes surrounding the cell is lower than the inside of the cell (more water) - movement INTO the cell

18
Q

what is a HYPERTONIC solution

A

concentration of solutes in the surrounding solution is higher than the inside of the cell ( less water)- so water moves OUT of the cell

19
Q

factors affecting diffusion

A

temperature - particles have more energy

surface area - how much space there is to diffuse across

concentration gradient - higher concentration on one side will increase the rate of diffusion

20
Q

what is an isotonic solution

A

concentration of solutes in the solution surrounding the cell is the same as the inside of the cell - no net movement

21
Q

what do all exchange surfaces need to have

A

large surface area

thin membrane only one cell thick

efficient blood supply (transports substances to maintain a concentration gradient)

22
Q

equation for magnification

A

size of image
————————
size of real object

23
Q

what is active transport

A

the movement of substances from a more dilute solution to a more concentrated solution against a concentration gradient
it requires energy

24
Q

stages of mitosis

A

the chromosomes line up at the centre of the cell and the cell fibres pull them apart

the two arms of each chromosome go to opposite ends of the cell

membranes form around each of the sets of chromosomes , the nucleus divides

the cytoplasm and cell membrane divides

the cell has now produced two new daughter cells

25
Q

how do prokaryotic cells replicate

A

through binary fission

26
Q

process of binary fission

A

the circular DNA and plasmids replicate

the cell gets bigger and the circular DNA strands move to the poles of the cell

the cytoplasm begins to divide and new cell walls begin to form

the cytoplasm dives and two daughter cell are produced

each daughter cell has one copy of the circular DNA but can have a variable number of copies if the plasmids

27
Q

diffusion definition

A

the spreading out of particles form an area of higher concentration to an area of lower concentration

28
Q

osmosis definition

A

the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration

29
Q

what organelle do bacterial cells not have

A

a true nucleus - they have plasmids and circular strands of DNA

chloroplasts

mitochondria

30
Q

how do you prepare a slide for microscopy practical

A
  1. add a drop of water to the middle of a clean slide
  2. cut up an onion and separate it out into layers , use tweezers to peel off some of the epidermal tissue from the bottom of one of the layers
  3. using the tweezers place the epidermal tissue into the water on the slide
  4. add a drop of iodine solution which is used to highlight objects in a cell by adding colour to them
  5. place a cover slip on top, to do this, stand the cover slip upright on the slide, next to the water droplet. then carefully tilt and lower it so it covers the specimen. do not get any air bubbles in otherwise they will obstruct the view of your specimen
31
Q

method for using a light microscope to look at your slide

A
  1. clip the slide you have prepared onto the stage
  2. select the lowest powered objective lens (the one that produces the lowest magnification )
  3. use the coarse adjustment knob to move the stage up to just below the objective lens
  4. look down the eyepiece, use the coarse adjustment knob to move the stage downwards until the image is roughly in focus
  5. adjust the focus with the fine adjustment knob, until you et a clear image of what is on the slide
  6. if you need to see the slide with greater magnification , swap to a higher powered objective lens and refocus
32
Q

how is a nerve cell specialised for rapid signaling

A

they are long to cover more distance and have branched connections at their ends to connect to other nerve cells and form a network throughout the body

33
Q

how is a sperm cell specialised for reproduction

A

it has a long tail and a streamlined head to help it swim to the egg

there are a lot of mitochondria in the cell to provide the energy needed

also carries enzymes in its head to digest through the egg cell membrane

34
Q

how are muscle cells specialised for contraction

A

these cells are long (so that they have space to contract ) and contain lots of mitochondria to generate the energy needed for contraction

35
Q

how are root hair cells specialised for absorbing water and minerals

A

gives the plant a big surface area for absorbing water and mineral ions from the soil

long extension

36
Q

how are the phloem and the xylem cells specilaised for transporting substances

A

to form the tubes the cells are long and joined end to end

xylem cells are hollow in the center and phloem cells have very few subcellular structures, so that stuff can flow through them

37
Q

where are the stem cells located in a plant

A

the meristem

38
Q

what is the method for the osmosis practical

A

cut up a potato into identical cylinders and get beakers with different sugar solutions in them of different concentrations - 0.5mol/dm3

measure the mass of the cylinders, then leave one cylinder in each beaker for twenty four hours

then take them out, dry them with a paper towel and measure their masses again

if the cylinders have drawn in water via osmosis they will have increased in mass but if the water has drawn out they will have decreased in mass

39
Q

how are the leaves structured so that gases and diffuse in and out

A

the underneath layer of the leaf is an exchange surface - the size of the stomata are controlled by the guard cells

the flattened shape of the leaf increases the area of this exchange surface so that it is more effective

the walls of the cells inside the leaf form another exchange surface , the air spaces inside the leaf increase the area of this surface so that there are more of a chance for carbon dioxide to get into the cells

40
Q

why is an electron microscope better than a light microscope

A

An electron microscope has much higher magnification and resolving power than a light microscope.

This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures

biology gcse (7 decks)

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