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Science GCSE > B1 > Flashcards

B1 Flashcards

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1
Q

Give 2 differences between a
light microscope and electron
microscope.

A
  • Electron microscopes have better
    resolution and magnification.
  • So you can see the specimen in
    more detail.
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2
Q

How do you calculate total
magnification?

A

Total magnification = eyepiece lens
magnification x objective lens
magnification

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3
Q

What is the function of a
mitochondria?

A

To release energy

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4
Q

What is the function of a
ribosome?

A

To make protein for growth and repair.

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5
Q

What is the function of the cell
membrane?

A

This controls the substances which can move in and out of the cell.

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6
Q

What is the function of the cell
wall in a plant cell?

A

This is made of cellulose. It provides support and protects the cell.

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7
Q

How is a bacterial cell different
from a plant or animal cell?

A

Bacterial cells don’t have a nucleus.

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8
Q

Where in a plant cell does
photosynthesis take place?

A

In the chloroplast

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9
Q

Give the steps you would use to
prepare a microscope slide.

A

1.Place specimen (cells on the slide).
2.Specimen must be thin to allow light
through.
3.Add stain.
4.Add cover slide on top at an angle.

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10
Q

Give an example of a prokaryotic cell.

A

Bacteria cell

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11
Q

Why must the specimen be thin
when preparing a slide?

A

To allow the light to pass through.

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12
Q

Give 2 adaptations of a sperm cell.

A

1.Have an acrosome to release
enzymes to break through jelly coat of
the egg.
2.Have a tail to swim.
3.Has mitochondria to release energy.

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13
Q

Give 2 adaptations of an egg cell.

A

Has a jelly coat which hardens to
prevent more than one sperm from
entering.
- Has nutrients in the cytoplasm.
- Has a haploid nucleus.

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14
Q

Give 2 adaptations of a ciliated
cell in the oviduct.

A
  • Has cilia to move the egg.
  • Has mitochondria to release energy.
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15
Q

Give 2 adaptations of a ciliated
cell in the digestive system.

A
  • Has villi to increase surface area.
  • Has mitochondria to release energy
    for active transport.
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16
Q

What are the two types of DNA in a bacterial cell?

A

Chromosomal DNA
plasmid

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17
Q

What do you call the pigment
(chemical) found inside chloroplasts
which helps to trap light for
photosynthesis?

A

Chlorophyll

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18
Q

When preparing a microscope
slide, what is the purpose of the cover
slip?

A
  • It protects the specimen.
  • It helps to hold the specimen in
    place.
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19
Q

Sperm and egg cells are haploid.
What does this mean?

A

Haploid means that the cell only has
half the genetic information (23
chromosomes).

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20
Q

What is meant by the ‘optimum’
temperature?

A

The optimum temperature is the
temperature at which the rate of
reaction for a particular enzyme is the
fastest.

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21
Q

What forms when an enzyme and substrate combine?

A

When an enzyme and substrate
combine, we call it an
enzyme-substrate complex.

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22
Q

What does ‘denature’ mean?

A

This is when the active site of the enzyme changes shape.

23
Q

What two main conditions could cause an enzyme to denature?

A

Temperature
pH

24
Q

What substrate does protease
break down?

A

Protein

25
Q

What is produced when protease breaks down protein?

A

Amino acids

26
Q

What substrate does amylase
break down?

A

starch

27
Q

What is produced when amylase breaks down starch?

A

glucose

28
Q

What substrate does lipase break down?

A

fats

29
Q

What two things are produced
when lipase breaks down lipids?

A

fatty acids
glucose

30
Q

What do you call the molecule
which fits into the active site of the
enzyme?

A

Substrate

31
Q

Enzymes are biological catalysts.
What does this mean?

A

Biological catalysts speed up the rate of reactions, like digestion, without being used up themselves.

32
Q

What term is used to describe the
fact that the shape of the substrate
allows it to fit into the active site of
the enzyme?

A

Complementary

33
Q

What do enzymes do?

A

Enzymes often break down large
insoluble molecules into smaller
soluble molecules. .

34
Q

Why do larger molecules need to be broken down into smaller
molecules?

A

Larger molecules need to be broken down into smaller molecules so that they can be absorbed through the small intestine.

35
Q

How can the lock and key model be used to help understand enzymes
and substrates?

A

Lock = enzyme
Key = substrate
The lock and key model shows that only one substrate molecule (key) has the correct shape to fit into the active site of the enzyme (lock).

36
Q

How does temperature affect the rate of an enzyme-controlled
reaction?

A

As the temperature increases the rate of an enzyme driven reaction increases as the enzyme and substrate
molecules have more kinetic energy so collide more often so more enzyme-substrate complexes are formed.

37
Q

When we increase substrate
concentration, the rate of reaction increases and then levels off. Why

A

It levels off because all of the enzymes are already bound to substrates.

38
Q

What is ‘diffusion’?

A

Diffusion is the random movement of
particles from a high concentration to
a low concentration.

39
Q

What is ‘osmosis’?

A

Osmosis is:

  • The movement of water.
  • From a high concentration of water
    to a low concentration of water.
  • Through a partially permeable
    membrane.
40
Q

What is ‘active transport’?

A

Active transport is:

  • The movement of particles from a
    low concentration to a high
    concentration.
  • It requires energy.
  • Movement is up the concentration
    gradient.
41
Q

In what two transport processes
do substances move down their
concentration gradient?

A
  1. Osmosis
  2. Diffusion
42
Q

Water moves through a partially
permeable membrane by what
process?

A

Omosis

43
Q

What is meant by ‘partially
permeable’ membrane?

A

Partially permeable means that some substances can pass through the
membrane, but other substances
can’t.

44
Q

Why is active transport referred to as an ‘active’ process?

A

It is an active process because it
requires energy.

45
Q

Why does active transport require
energy?

A

Active transport requires energy
because substances are moved against the concentration gradient.

46
Q

What is meant by ‘concentration
gradient’?

A

This is the difference between two concentrations.

47
Q

What is the equation to work out
% change in mass?

A

% change = change in mass/starting
mass x 100

48
Q

In an experiment, what is meant by the independent variable?

A

The independent variable is the thing we are changing.

49
Q

In an experiment, what is meant by the dependent variable?

A

The dependent variable is the thing we are measuring.

50
Q

In an experiment, what is meant by the control variable?

A

The control variable is the thing we keep the same.

51
Q

Why is it important that we have control variables?

A

It is important because:
- we should only be changing
one variable (independent
variable)
- so we can compare results

52
Q

Why do we repeat experiments?

A

We repeat experiments:
- to identify anomalies
- so we can calculate a
mean/average

53
Q

What is meant by ananomalous
result?

A

An anomalous result is one which doesn’t follow a trend or pattern in results.

Science GCSE (6 decks)

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