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BIOLOGY GCSE EDEXCEL > Topic 1 - Keys > Flashcards

Topic 1 - Keys Flashcards

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1
Q

what are eukaryotes

A

cells with nuclei

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2
Q

what are prokaryotes

A

cells without nuclei

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3
Q

what is the function of the nucleus

A

contains genetic material, including DNA which controls the cell’s activities

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4
Q

what is the function of the cytoplasm

A

jelly-like material containing dissolved nutrients + salts + structures (organelles). Many chemical reactions happen here

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5
Q

what is the function of the cell membrane

A

it is permeable to some substances but not others so controls movement of substances in and out of cell.

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6
Q

what is the function of the mitochondria

A

contains enzymes for respiration, and where most energy is released in respiration.

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7
Q

what is the function of the ribosomes

A

where protein synthesis occurs

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8
Q

what is the function of the chloroplasts

A

contains chlorophyll (a green pigment) which absorbs light energy for photosynthesis.

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9
Q

what is the function of the vacuole

A

It has cell sap to keep cell turgid and swollen.

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10
Q

what is the function of the cell wall

A

provides structure and protection. Made of cellulose in plants.

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11
Q

what is the function of the chromosomal dna

A

it is DNA loose in the cytoplasm, not contained inside the nucleus.

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12
Q

what is the function of the plasmid dna

A

small closed circles of DNA in cytoplasm, can move from one bacterium to another.

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13
Q

what is the function of the flagella

A

tail to enable movement.

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14
Q

what cell structures do animal cells contain

A

nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

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15
Q

what structures do plant cells contain

A

nucleus, cytoplasm, ribosome, vacuole, mitochondria, cell membrane, cell wall, chloroplast

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16
Q

What are the adaptations of a sperm cell?

A
  • It has acrosomes; contains enzymes so sperm can penetrate and digest the egg
  • the head contains genetic material; for fertilisatoin in a haploid nucleus
  • Lots of mitochondria; lots of energy release to swim
  • The tail enables swimming and movement
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17
Q

What are the adaptations of an egg cell?

A
  • It has lots of cytoplasm which contains nutrients for growth of early embryo
  • it has haploid nucleus containing genetic material for fertilisation
  • the cell membrane changes after fertilisation so that only 1 sperm enters
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18
Q

What are adaptations of ciliated epithilial cell?

A

It has cilia on surface beat to move fluids and particles up the trachea or into the stomach to be coughed up or destroyed (e.g. mucus)

19
Q

Resolution definition

A

shortest distance between 2 points on a speiment that can be seen as 2 different points by observer

20
Q

differences between light microsocope and electron microscope

A

LIGHT MICROSCOPE:
- light beam used
- see colour images
- smaller
- easier to use
- specimen can be alive
- lower resolving power
- lower magnificationm

ELECTRON MICROSCOPE:
- electron beam used
- black and white images
- specimen must be dead
- training required to use
- greater resolution
- greater magnification

21
Q

how to prepare onion slide for light microscope

A
  1. use pipette to place drop of water in centre of slide
  2. remove thin lyaer of onion with tweezers
  3. place onion layer in water droplet
  4. place iodine drop over onion slice with pipette
  5. place cover slide over specimen
  6. place slide onto microscope stage - ensure onion is at centre of stage
22
Q

how to work out magnification

A

Magnification = image size/actual size

23
Q

What is an enzyme?

A

A biological catalyst which speeds up rate of reaction but aren’t used up themselves

24
Q

Mechanism of enzymes

A

Enzymes are substrate-specific so active site of enzyme is complementary to substrate. When enzymes and substrates collide, an enzyme-substrate complex forms. After reaction, products leave the enzyme’s active site so it is free to collide with another substance.

25
Q

How to enzymes denature?

A

Bonds holding enzymes are disrupted due to high temperatures or extreme pHs. The active site shape is changed so enzymes can’t bind with substrate. It is irreversible as the chain of amino acids unravel.

26
Q

What are factors affecting rate of enzyme activity?

A
  1. Temperature - activity increased when temp up - molecules gain kinetic energy and move faster meaning more successful collisions - rate of reaction is increased.
  2. Low temps - fastest rate occurs at optimum rate, if it is too low or too high it will cause denaturing - if the pH is too far from optimum, bonds will break. Optimum pH for most human enzymes is pH7, stomach acid is pH1.
  3. Substrate concentration - if substrate concentration increases, activity increases. As concentration increases, likelihood increases of enzyme-substrate complexes being made increases. But the rate plateus at the saturation point - if enzyme concentration is fixed but substrate conc increases, all active sites become saturated; no more e-s complexes can form.
27
Q

What are digestive enzymes and products for digestive enzymes?

A
  • CARBOHYDRATES broken down by AMYLASE producing GLUCOSE
  • LIPIDS broken down by LIPASE producing GLYCORD + 3 FATTY ACIDS
  • PROTEIN broken down by PROTEASE producing AMINO ACIDS
28
Q

Where is protease found

A

in the small intestine and stomach.

29
Q

What is diffusion?

A

Passive transport of substances from high to low concentrations. It occurs in liquids and gases as particles move randomly.

30
Q

What are the factors affecting rate of diffusion?

A
  1. Temperature
  2. Concentration gradient
  3. Diffusion distance
  4. Surface area
31
Q

How does temperature affect diffusion

A

Increase in temp means faster diffusion

More kinetic energy of particles = more collisions

32
Q

How does concentration gradient affect diffusion

A

Greater the difference in concentration = increase in rate

33
Q

How does diffusion distance affect diffusion

A

The shorter distance = increase in rate because particles have less to travel through

34
Q

How does surface area affect diffusion

A

larger SA = increase in rate because more space for particles to moce through

35
Q

What is osmosis?

A

passive transport of water from area of high water concentration to low concentration across a semi permeable membrane to reach state of equilibrium

36
Q

What is hypertonic solution

A

Environment outside cell has high solute concentration than inside.
Water moves out of the cell.
Cell becomes plazmolyzed.

37
Q

What is hypotonic solution?

A

Environment outside has lower solute concetnration than inside.
Water moves into the cell.
Cell swells become turgid.

38
Q

What is isotonic solution?

A

Environment outside and inside cell have equal solute concetration.
No net movement of water molecules.
Cell stays the same - flaccid.

39
Q

What is active transport?

A

Transport used to move molecules from low to high concentration - against the concentration gradient. Requires ATP energy.

40
Q

How does calorimetry work?

A
  1. Take tube of cold water
  2. Record starting temperature of water
  3. Hold burning food sample beneath test tiube
  4. Record final temp of water when food burnt up
  5. Work out the energy transfered to water by using:
    energy transfered = mass of water x temp increase x 4.2
41
Q

What is test for starch

A

Iodine solution
Iodine goes from orange to blue/black

42
Q

What is test for sugars

A

Benedict’s solution
Blue to red/brown

43
Q

What is test for protein

A

Biuret’s test (potassium hydroxide + copper sulfate)
Blue to violet

44
Q

What is test for lipids

A

Emulsion test (ethanol)
White emulsion layer formed at top of sample

BIOLOGY GCSE EDEXCEL (7 decks)

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