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Gcse Biology > B1 - Cell Level Systems > Flashcards

B1 - Cell Level Systems Flashcards

1
Q

Examples of prokaryotes:

A
  • Escherichia coli = cause food poisoning
  • Streptococcus bacteria = cause sore throats
  • Streptomyces bacteria = kills disease-causing bacteria (in soil)
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2
Q

Cell stains:

A
  • methylene blue = animal cell nuclei
  • iodine solution = plant cell nuclei
  • crystal violet = bacterial cell walls
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3
Q

Types of electron microscopes:

A
  • TEM = most magnified image, beam of electrons passed through sample & focused
  • SEM = 3D image of surface, sends beam of electrons across surface, reflected electrons collected
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4
Q

Mm —> um —> nm

A

x 1000, x 1000

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5
Q

How many chromosomes do humans have

A

46 in each cell

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5
Q

Magnification equation

A

M = I/A

I = image
A = actual
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6
Q

Enzymes

A

= biological catalysts, proteins that speed up reactions in body without being used up themselves

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7
Q

Describe the point of saturation in increasing substrate concentration in an enzyme controlled reaction:

A
  • at certain point, all enzymes bound to substrate molecule = point of saturation, maximum rate of reaction
    no increase will make a change in rate of reaction
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8
Q

What is ATP (adenine triphosphate) used for:

A
  • movement, contract muscle cells
  • warmth, (exothermic, transfers energy by heating)
  • synthesis large molecules from smaller ones, make new cell material
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9
Q

Cellular respiration:

A

An exothermic chemical reaction that produces ATP

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10
Q

Why do mitochondria have folded inner membranes?

A
  • to increase surface area, where specific enzymes that control each chemical reaction in cellular respiration are found
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11
Q

What cells need lots of mitochondria(for energy)

A
  • muscle cells (transfer energy to contract muscles for movement)
  • liver cells (carry out many reactions)
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12
Q

Fermentation word and symbol equation:

A

Glucose —> ethanol + carbon dioxide

C6H12O6 —> 2C2H5OH + 2CO2

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13
Q

Why may fermentation take place in plants

A
  • no oxygen is available

Eg. In roots of plants in waterlogged soils

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14
Q

Anaerobic respiration word equation:

A

Glucose —> lactic acid

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15
Q

Metabolic rate:

A

= Speed at which chemical reactions in your cells transfer energy from its chemical stores in food

16
Q

State the polymer, enzyme that breaks it down and monomers for digestion of carbohydrates and starch:

Where does this happen?

A

Carbohydrate molecule -(carbohydrase enzyme)-> sugar molecules

Starch -(amylase enzyme)-> glucose monomers

= in mouth & small intestine

17
Q

State polymer, enzyme and monomer for digestion of proteins:

Where does this happen?

A

Protein -(protease enzyme)-> amino acid molecules

= inside stomach & small intestine

18
Q

State polymer, enzyme and monomers for digestion of lipid molecules

Where does this happen?

A

Lipid molecules -(lipase enzyme)-> fatty acid molecules & glycerol molecules

= inside small intestine

19
Q

what happens once food molecules are fully digested?

A

= absorbed into bloodstream, travel to cells that need them

20
Q

Explain how the reactants of photosynthesis enter the plants:

A
  • water: enters roots though soil through root hair cells, diffuses by osmosis
  • carbon dioxide: diffuses from air into plant through stomata in leaf
21
Q

Two stages for series of photosynthesis reactions:

A

Stage 1 (light dependent): energy transferred from light splits water molecules into oxygen gas & hydrogen ions

Stage 2(light independent): carbon dioxide gas combines with hydrogen ions to make glucose

22
Q

Instrument for measuring light intensity:

A

= photometer

23
Q

What happens to the glucose produced in respiration, what are the other molecules converted into?

A
  • some used immediately in respiration
  • fats & oils: food store & growth
  • sucrose: stored in fruit
  • starch: food store
  • cellulose: form cell walls
    • nitrogen = proteins: growth & repair
24
Q

Limiting factors of photosynthesis:

A
  • light intensity (more light = more energy for photosynthesis)
  • carbon dioxide concentration (most common limiting factor)
  • temperature (enzyme-controlled reactions)
25
Q

How can you measure the rate of photosynthesis?

A

= measure how much oxygen/glucose plant makes in given time
Formula: rate = 1/time

= calculate increase in biomass in given time (glucose used to make new cells)

26
Q

Relative light intensity equation

A

Relative light intensity = 1/distance from light source^2

27
Q

How can i alter light intensity during photosynthesis experience to:

A

Place light source at different distances from plant

28
Q

How can I alter carbon dioxide concentration for a photosynthesis experiment:

A

Add different masses of potassium hydrogen carbonate(releases CO2 to atmosphere) powder to the water

29
Q

How can I alter temperature in photosynthesis experiment:

A

Place the apparatus in water baths at different temps

30
Q

How can i stop a lamp heating the plant when testing for light intensity? Why?

A

Put a glass tank of water between plant and lamp

As it is another limiting factor, would not give accurate results

31
Q

Explain how to test for starch in a plant: why do we do this?

A

(plant converts glucose produced during photosynthesis to starch)

  • place leaf into boiling tube of boiling ethanol to remove chlorophyll
  • wash leaf with water to remove ethanol & soften leaf
  • spread leaf out on white tile
  • add few groups of iodine solution
  • if starch present, iodine will turn from yellow-brown to blue-black
32
Q

Why should you keep the plant in the dark for 24 hours before carrying out photosynthesis experiments:

A

= to destarch the plant, to make sure no starch is present in leaves before in the leaves tested

33
Q

How can you prove chlorophyll is needed for photosynthesis?

A

= place a destarched variegated plant in sunlight for several hours,
- then test 1 leaf for presence of starch

(Variegated plant = only have chlorophyll in some areas of leaf, so some green, some white)

34
Q

How can you prove light is needed for photosynthesis:

A

= cover part of one leaf with black card/tin foil of a destarched plant

  • place plant in sunlight for several hours
  • remove card from leaf & test leaf for presence of starch
35
Q

How can you prove carbon dioxide is needed for photosynthesis?

A
  • place destroyed plant inside polythene bad
  • add pot of soda lime(absorbs CO2 & water vapour) then seal bag
  • place plant in sunlight for several hours
  • test leaves for presence of starch
36
Q

How can you prove oxygen is given off during photosynthesis?

A
  • place upturned test tube above an aquatic plant (Elodea)
  • put apparatus in light for maximum photosynthesis
  • when full tube of gas is collected, place glowing splint inside tube, will relight if oxygen gas present

Gcse Biology (15 decks)

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