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OCR A GCSE Biology (B1-B3) > B1.1 > Flashcards

B1.1 Flashcards

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1
Q

Nucleus:

  • what is it’s purpose
  • what does it contain (2)
A

+ Controls the activities of the cell
+ Contains organism’s genetic material, arranged as chromosomes
+ Contains instructions to make new cells or organisms

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2
Q

What happens within the mitochondria?

  • what does it contain to enable this process
  • how does that help the body
A

+ where respiration happens
+ enzymes there allow glucose and oxygen to react together
+ reactions transfer vital energy to the organism

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3
Q

What is the Cell membrane do?

- why may it be called a ‘sense organ’?

A

+ Acts as a barrier that controls which substances pass in and out of the cell
+ Membrane also contains receptor molecules

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4
Q

Cytoplasm

A

+ A ‘jellylike’ substance

+ where chemical reactions happen

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5
Q

Do Prokaryotic or Eukaryotic cells contain a nucleus?

A

Eukaryotic cells

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6
Q

State key facts about Eukaryotic cells

  • size
  • example of them
  • size relative to other cells
A

+ between 10 μm and 100 μm (micrometers)
+ Plant and Animal cells are an example
+ They are generally large and complex
+ Larger than prokaryotic cells

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7
Q

State key facts about Prokaryotic cells

A 
\+ do NOT contain a nucleus
\+ genetic material floats in the cytoplasm 
\+ 1 μm to 10 μm 
\+ Bacterial cells are an example 
\+ Smaller than Prokaryotic cells
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8
Q

What is the role of Chloroplasts?

  • what does it contain to enable that
  • where is it found
A

+ where photosynthesis occurs
+ Contain green chlorophyll
+ which transfers energy from the Sun to light
+ Only in green parts of plant

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9
Q

What is the role of the Cell wall?

- what is it made of

A

+ Made of tough fibre called cellulose

+ Supports the cell from falling

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10
Q

What is the role of Vacuole?

- what is within it

A

+ Full of cell sap

+ Helps keep the cell rigid and upright

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11
Q

How many micrometers are in a meter?

1 μ

A

1,000,000

one million

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12
Q

State the difference between Prokaryotic and Eukaryotic cells

A

Eukaryotic cells have a nucleus and prokaryotic cells do not.
Eukaryotic cells are larger than Prokaryotic cells.

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13
Q

State the similarities and differences between animal and plant cells

A

Similarities - Cytoplasm, Cell membrane, Nucleus, Mitochondria
Differences - Plants have cell wall, vacuole, chloroplasts

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14
Q

How does a light microscope work?

A

Light is passed through an object on the stage and then eyepiece lenses are used to see the object in more detail

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15
Q

What are light microscopes used for?

A

To observe small structures in detail

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16
Q

State 7 components of a light microscope

A
  • eyepiece lens
  • objective lens
  • stage
  • slide
  • light
  • fine focus
  • coarse focus
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17
Q

What is the first three stages to observe cells using a light microscope?

A

1) Move the stage to its lowest position
2) Select the objective lens with the lowest magnification
3) Place the slide (with the cells) on the stage

18
Q

What are the last three stages to observe a cell using a light microscope?

A

4) Turn the coarse focus knob
5) Turn the fine focus knob
6) to see the cell clearer, repeat the steps using a higher magnification

19
Q

What is the equation to find out the total magnification of a microscope?

A

eyepiece lens magnification x objective lens magnification

20
Q

Why are cells stained when observed under a microscope?

A
  • to increase the contrast
  • since cells are colourless
  • the stains are used to see sub-cellular features
21
Q

Explain what the term “higher resolution” means

A

The image/cell is seen in high detail

22
Q

What is an iodine solution stain used for?

A

makes it easier to see plant cell nuclei

23
Q

What is methylene blue stain used for?

A

makes it easier to see the nucleus of an animal cell

24
Q

What is the crystal violet stain used for?

A

stains bacterial cell walls

25
Q

What is the resolution of a light microscope?

A

2 x 10^-7

2 x 10 to the power of -7

26
Q

How do TEM work?

A

1) beam of electrons pass through a thin slice of the sample
2) Beam is focused to produce an image

27
Q

How does a SEM work?

A

1) sends a beam of electrons across the surface of a specimen
2) the reflected electrons are collected to produce an image

28
Q

What does TEM stand for?

And what dimension does it come in?

A

Transmission Electron Microscope

2D - ELECTRONS TRANSMIT THROUGH SAMPLE

29
Q

What does SEM stand for?

And what dimension does it come in

A

Scanning electron microscope

3D - SCANS OVER OBJECT

30
Q

State 4 advantages of a light microscope compared with an electron microscope

A
  • Cheap to buy and operate
  • Small and portable
  • Specimens can be living or dead
  • Natural colour of sample can be seen
31
Q

State 4 qualities of a electron microscope

A
  • High resolution ( up to 0.1nm)
  • Large and difficult to move
  • Expensive
  • Specimens must be dead
  • Black and White images produced
32
Q

How has electron microscopy increased our understanding of subcellular structures?

A

It has allowed scientists to see detail within subcellular structures

33
Q

what is the magnitude of this symbol:

μm

A

MICROMETER

10^-6m

34
Q

what is the magnitude of this symbol:

nm

A

nano-meter

10^-9

35
Q

define monomer

A

a single molecule that can be bound to many copies of itself to make a larger molecule

36
Q

define polymer

A

a molecule composed of many repeating monomers

37
Q

what are proteins made from?

A

amino acids

38
Q

What is the formula to work out the magnification of a picture?

A

image size
————
actual size

i
a\m

39
Q

What’s important about ribosomes?

A
  • allow Translation to occur

- are the site of ‘protein synthesis’

40
Q

Define magnification

A

How many times larger an image is seen through a microscope compared to a real specimen

41
Q

Define resolution

A

The ability to distinguish between two or more objects close together

OCR A GCSE Biology (B1-B3) (12 decks)

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