Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Biology Year 1 > Chapter 3 - Cell structure > Flashcards

Chapter 3 - Cell structure Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is an object?

A

The material placed under the microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an image?

A

The appearance of the material viewed under the microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is the resolution of an electron microscope greater than that of an optical microscope?

A

Electrons have a very small wavelength compared to light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Equation for magnification

A

Magnification = size of image/size of real object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is magnification?

A

How much bigger the image is than the specimen you’re looking at

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is resolution?

A

How well a microscope can distinguish between two points that are close together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do optical microscopes use to form an image?

A

Light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do electron microscopes use to form an image?

A

Electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Maximum resolution of a light microscope

A

0.2 micrometres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Maximum magnification of a light microscope

A

1500 x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Maximum resolution of electron microscopes

A

0.0002 micrometres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Maximum magnifiation of electron microscopes

A

1,500,000 x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the two types of electron microscope?

A

Transmission electron microscope (TEM)

Scanning electron microscope (SEM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do transmission electron microscopes work?

A

A beam of electrons is focussed onto a specimen using electromagnets. The electrons are transmitted THROUGH the specimen. Denser parts of the specimen absorb more electrons, so they appear darker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the main limitations of the TEM? (3)

A

They can only be used on thin specimens
The whole system must be observed in a vacuum - living specimens can’t be viewed
A complex preparation process means artefacts are common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are artefacts?

A

Things that you can see on the microscope but aren’t part of your specimen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How many micrometres are in a millimetre?

A

1,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many nanometres are in a micrometre?

A

1,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do scanning electron microscopes work?

A

A beam of electrons is scanned onto the surface of a specimen. This knocks electrons off of the specimen which are gathered in a cathode ray tube to form an image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Advantages of TEM

A

High resolution images mean you can see internal structures like chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Advantages of SEM

A

They can be used on thick, and living, specimens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Disadvantages of SEM

A

The resolution is lower than TEM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is an eyepiece graticule?

A

A transparent ruler with numbers but no units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How to calibrate a microscope?

A

1) Divide total length of stage micrometre by how many intervals to find one micrometre unit
2) Find a point where the two lines are equal
3) Work out how many micrometre units equal how many eyepiece units
4) Convert the stage micrometre units to micrometres
5) Divide stage micrometre units by eyepiece units to find the value of one eyepiece unit
6) This can be used in calculations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is cell fractionation?

A

The process where cells are broken up and different organelles they contain are separated out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

During homogenisation, why is the solution:

a) cold?
b) the same water potential as the tissue?
c) buffered?

A

a) to reduce enzyme aactivity that could break down organelles
b) to prevent organelles bursting or shrivelling due to osmosis
c) any change in pH could affect the organelles or enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens during homogenisation?

A

Cells are broken up in a blender to release organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens during filtration?

A

The homogenate is filtered to remove any large sections of cells and debris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What happens during ultracentrifugation?

A

The filtrate is poured into a test tube, placed in the centrifuge and spun slowly
The heaviest organelles sink to the bottom, forming the pellet, whilst the rest of the organelles stay suspended in a fluid called the supernatant
The supernatant is drained off, poured into another test tube and spun at a higher speed
The next heaviest organelles form the pellet and are removed
The process repeats until the desired organelle forms the pellet, which can then be studied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

*Description of the nucleus

A

A large organelle, which is surrounded by the nuclear envelope (a double membrane), covered in pores to allow mRNA to leave. Inside the nucleus is nucleoplasm and in this are chromosomes, containing DNA. One or more nucleoli can also be found her, which are used for making ribosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

*Function of the nucleus

A

The nucleus controls the activities of the cell by controlling the transcription of DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

*Description of mitochondria

A

Mitochondria have a double membrane, the innermost of which is folded to form structures called cristae. Surrounding these cristae is a matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

*Function of cristae

A

Large surface area for aerobic respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

*Function of matrix

A

Contains enzymes involved in respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

*Function of mitochondria

A

The site of aerobic respiration, which produces ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

*Description of cell surface membrane

A

The membrane found on the surface of animal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

*Function of cell surface membrane

A

Controls what enters and leaves cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

*Rough size of mitochondria

A

Between 2 and 10 um

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

*What is the chloroplast envelope?

A

A double membrane surrounding the organelle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

*What are grana?

A

Stacks of thylakoid membranes inside chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

*What is the stroma?

A

A matrix where the sugars are synthesised during photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

*Function of chloroplasts

A

Site of photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

*How are chloroplasts adapted for photosynthesis?

A

The grana provide a large surface area for the first stage of photosynthesis
Chloroplasts contain ribosomes and DNA so they can quickly make proteins required for photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What are the two types of endoplasmic reticulum?

A

Smooth endoplasmic reticulum (SER)

Rough endoplasmic reticulum (SER)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the RER?

A

A system of membranes covered in ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Functions of the RER

A

Provide a pathway for proteins to move throughout the cell

Provide a large area for protein synthesis

47
Q

Functions of the SER

A

Synthesise, store and transport lipids and carbohydrates

48
Q

What are cisternae?

A

A stack of membranes that make flattened sacks

49
Q

Functions of Golgi apparatus

A

Processes and packages new lipids and proteins

Form lysosomes

50
Q

Functions of Golgi apparatus

A

Processes and packages lipids and proteins

51
Q

What are Golgi vesicles?

A

Fluid-filled sacks produced by the Golgi apparatus

52
Q

Function of Golgi vesicles

A

Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell

53
Q

When are lysosomes formed?

A

When vesicles contains enzymes like lipases and proteases

54
Q

What are lysozymes?

A

Enzymes found in lysosomes which hydrolyse the cell walls of certain bacteria

55
Q

Functions of lysosomes

A

Digest worn-out organelles and cells after they have died

Hydrolyse bacteria cells during phagocytosis

56
Q

What are the two types of ribosome?

A

80S - found in eukaryotic cells, relatively big

70S - found in prokaryotic cells, mitochondria and chloroplasts, smaller

57
Q

Description of ribosomes

A

A very small organelle, made of proteins and RNA

58
Q

Function of ribosomes

A

Protein synthesis

59
Q

Function of microvilli

A

Increase surface area for absorption

60
Q

*What is a cell wall?

A

A rigid structure surrounding cells in plants, algae and fungi. It consists of cellulose embedded in a matrix

61
Q

*Functions of the cell wall

A

To prevent the cell bursting from the movement of water

Gives mechanical support to the cell

62
Q

*What are cell walls made from in fungi?

A

Chitin

63
Q

*What is the tonoplast?

A

The membrane surrounding the vacuole

64
Q

*What is a vacuole?

A

A fluid filled sack surrounded by the tonoplast

65
Q

*Function of a vacuole

A

Stores water to maintain water and keep the cell rigid and the plant turgid
Helps to isolate unwanted chemicals

66
Q

Why do cells become specialised?

A

To carry out specific functions

67
Q

How do cells become specialised?

A

Certain genes can be turned on and off

68
Q

What is a tissue?

A

A group of cells working together to perform a specific function

69
Q

Function of the epithelial tissue

A

Covers the inside and outside of organs

70
Q

Function of xylem

A

Transports water and mineral ions throughout the cell and also gives mechanical support

71
Q

What is an organ?

A

A variety of tissues coordinated to perform a variety of functions

72
Q

What does muscular tissue do in the stomach?

A

Churns contents

73
Q

What does epithelial tissue do in the stomach?

A

Protects stomach lining

74
Q

Which of the blood vessels are organs and which are tissues?

A

Organs: arteries and veins
Tissue: capillaries

75
Q

Function of phloem

A

Moves food away from the leaves in a plant

76
Q

Function of the epidermis in a plant

A

To protect the leaf

77
Q

Function of the spongy mesophyll in a plant

A

Gaseous diffusion

78
Q

Function of the palisade mesophyll in a plant

A

Photosynthesis

79
Q

What does the digestive system do?

A

Digests and processes food

80
Q

What does the respiratory system do?

A

Breathing and gas exchange

81
Q

What does the circulatory system do?

A

Pumps and circulates blood

82
Q

*What are cell walls made from in bacteria?

A

The glycoprotein murein

83
Q

Function of slime capsule

A

Protects bacterium from other cells and helps them group together

84
Q

Which ribosomes are found in bacteria cells?

A

70S

85
Q

*Function of circular DNA

A

Contains information needed for bacteria cells to replicate

86
Q

*Function of plasmid

A

Contains genes that may help the bacteria survive in adverse conditions

87
Q

*Is the DNA of bacteria cells associated with proteins?

A

No

88
Q

Why are viruses described as acellular?

A

They are nucleic acids surrounded by a protein called the capsid - they aren’t alive

89
Q

What is the function of attachment proteins and where are they found?

A

They are found sticking out from around the capsid and help virus cling to a host cell

90
Q

How do viruses replicate?

A

They use proteins to attach to host cells

They inject their DNA into the host cell, which makes the cell replicate the viral particles

91
Q

Why can viruses only infect one type of cell?

A

Their attachment proteins are complementary to just one receptor cell

92
Q

Process of binary fission

A

The DNA and plasmids in the cell replicate
The cell gets bigger and the DNA moves to opposite ends of the cell, where it attaches to the membrane
The cytoplasm begins to divide and new cell walls begin to form
A new cell wall forms between the two molecules of DNA, creating two identical daughter cells

93
Q

*What is mitosis?

A

A parent cell divides to produce two genetically identical daughter cells

94
Q

*3 uses of mitosis?

A

Growth, repair and reproduction

95
Q

*What are the three stages in the cell cycle?

A

Interphase
Nuclear division
Cytokinesis

96
Q

*Which stage isn’t part of mitosis?

A

Interphase

97
Q

*How to remember the stages of the cell cycle?

A

IPMAT

98
Q

*What happens during interphase? 2

A

The cell’s DNA unravels and replicates

The organelles and ATP are replicated

99
Q

*What happens during prophase? 3

A

The chromosomes condense and become visible
Centrioles move to opposite ends of the cell, forming the spindle apparatus
The nuclear envelope breaks down

100
Q

*What happens in metaphase? 2

A

The chromosomes line up along the cell’s equator

The spindle fibres attach to the centromere

101
Q

*What happens in anaphase? 2

A

The centromeres divide, separating the chromatids. The spindles contract and pull chromatids to the cell’s poles

102
Q

*What happens during telophase? 2

A

The chromosomes reach the poles and unravel

The cytoplasm divides and two nuclear envelopes form, leaving two identical daughter cells

103
Q

*What is cytokinesis?

A

The process by which the cytoplasm divides

104
Q

What is cancer?

A

A group of diseases characterised by a growing disorder of cells

105
Q

Characteristics of benign tumours

A

Grow slowly, are more compact and less life threatening

106
Q

Characteristics of malignant tumours

A

Grow quickly, less compact and are more life threatening

107
Q

How do cancer drugs work?

A

They disrupt the cell cycle to stop the tumour dividing and growing

108
Q

How does chemotherapy work?

A

Chemicals prevent the synthesis of enzymes needed for DNA replication

109
Q

How does radiotherapy work?

A

Radiation damages DNA so the cell kills itself

110
Q

Formula for mitotic index

A

Number of cells with visible chromosomes/ total number of cells observed

111
Q

Why are hair cells often affected by cancer drugs?

A

The drugs target cells that divide rapidly, such as hair cells

112
Q

Why do specimens have to be kept in a vacuum before using an electron microscope?

A

The air would otherwise absorb the electrons and prevent them reaching the specimen

113
Q

*What chromosomes do women have?

A

XX

114
Q

*What chromosomes do men have?

A

XY

A Level Biology Year 1 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions