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Biology GCSE AQA > B1 - Cell Biology > Flashcards

B1 - Cell Biology Flashcards

(95 cards)

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1
Q

What are eukaryotic cells?

A

Complex cells, animal and plant cells.

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2
Q

What is the nucleus of a plant cell?

A

It contains genetic material and controls the activities of the cell.

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3
Q

What is a cytoplasm?

A

It’s a gel like substance, containing enzymes, where most chemical reactions take place.

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4
Q

What is a cell membrane?

A

The barrier to the cell, it holds it together and controls what goes in and out.

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5
Q

What is the mitochondria?

A

Where the reactions for aerobic respiration take place.

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6
Q

What is a ribosome?

A

It is where proteins are made.

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7
Q

What is a cell wall?

A

It supports the cell and strengthens it. It’s made of cellulose.

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8
Q

What is a permanent vacuole?

A

Contains cell sap: a weak solution of sugar and salts.

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9
Q

What are chloroplasts?

A

They contains green substance called chlorophyll which is needed for photosynthesis. They are also where photosynthesis occurs.

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10
Q

What type of cells are bacteria?

A

Prokaryotic

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11
Q

What do bacteria cells have instead of a nucleus?

A

A strand of DNA floating freely in the cytoplasm, and sometimes rings of DNA called plasmids

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12
Q

What are microscopes?

A

Devices that allow us to get a magnified image of something we couldn’t see with the naked eye

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13
Q

What do light microscopes use to form an image?

A

Light and lenses

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14
Q

What do electron microscopes use to form an image?

A

Electrons

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15
Q

Do electron or light microscopes have a higher magnification?

A

Electron

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16
Q

Do electron or light microscopes have a higher resolution?

A

Electron

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17
Q

What is resolution?

A

The ability to distinguish between two points, a sharper image

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18
Q

Magnification =

A

Image size/real size

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19
Q

What is a slide?

A

A clear strip of plastic or glass that you put the specimen on

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20
Q

What is the first thing you do in preparing a slide? (Onion)

A

Add a drop of water to the centre of the slide

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21
Q

What is the second thing you do in preparing a slide? (Onion)

A

Using tweezers, take a thin layer of the onion

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22
Q

What is the third thing you do in preparing a slide? (Onion)

A

Place the thin onion layer on the water droplet on the slide

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23
Q

What is the fourth thing you do in preparing a slide? (Onion)

A

Add a drop of iodine solution

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24
Q

What is the fifth thing you do in preparing a slide? (Onion)

A

Place a cover slip over the specimen

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25
Why do you add iodine to a slide?
To stain the specimen
26
How do you place the cover slip on the slide?
Stand it upright on one edge, then tilt and lower it until it covers the specimen
27
Which lens do you use first on a light microscope?
The lowest powered objective lens
28
What does the coarse adjustment knob do on a light microscope?
Move the stage up and down
29
What does the fine adjustment knob do on a light microscope?
Adjust the focus
30
What is differentiation?
The process in which a cell becomes specialised
31
When does most differentiation occur?
When an organism develops
32
When do plants lose the ability to specialise?
Never
33
What is the purpose of differentiating cells in mature animals?
For repairing and replacing cells
34
What is the function of a sperm cell?
To get male DNA to the female DNA
35
How is the sperm cell specialised for its function?
Long tail, streamlined, lots of mitochondria
36
What is the function of a nerve cell?
To carry electrical signals around the body
37
How are nerve cells specialised for their function?
They are long and branched
38
What is the function of a muscle cell?
To contract
39
How are muscle cells specialised for their function?
They are long and have lots of mitochondria
40
What is the function of a root hair cell?
To absorb water and minerals from the soil
41
How are root hair cells specialised for their function?
Big surface area
42
What is the function of phloem and xylem cells?
They form phloem and xylem tubes that transport food and water around plants
43
How are phloem cells specialised for their function?
They have very few sub-cellular structures
44
How are xylem cells specialised for their function?
Hollow in the centre
45
What are chromosomes?
Coiled up DNA molecules
46
Where in the cell are chromosomes?
The nucleus
47
How many chromosomes does a normal body cell have?
46, 23 pairs
48
How many chromosomes are from the mother and how many are from the father?
23 each
49
What is mitosis?
When cells divide
50
What is the end result of mitosis?
Two identical cells
51
What does the cell have to to do before it divides?
Duplicate its DNA and increase the amount of sub-cellular structures
52
What happens when the cell actually divides?
The chromosomes are pulled apart, new nucleus membranes form around each half, then cytoplasm and cell membrane divide
53
What type of cells divide by binary fission?
Prokaryotic
54
What happens in binary fission?
DNA and plasmids replicate, cells expands, DNA separate, new cell walls for, cell membrane divides
55
How many copies of the DNA strands does each new daughter cell have after binary fission?
One
56
How many plasmids does each daughter cell have after binary fission?
A variable number
57
What do bacteria need to divide?
The correct conditions
58
What is mean division time?
The average amount of time a bacterial cell takes to divide
59
How do you calculate the number of cells produced in a period of time?
Total time the bacteria are producing cells/mean division time = number of divisions. 2 to the power of the number of divisions = number of cells produced
60
What is another name for undifferentiated cells?
Stem cells
61
Where can stem cells be found?
Embryos or adult bone marrow
62
How many types of cell can embryonic stem cells differentiate into?
Any
63
How many types of cells can adult stem cells differentiate into?
Only a few specific types, such as blood cells
64
What can stem cells do for medicine?
Cure disease
65
What type of cells might be replaced by stem cells?
Faulty blood cells, insulin producing cells for diabetics, nerve cells for people who are paralysed
66
How can rejection be avoided in the use of stem cells?
Therapeutic cloning, giving an embryo the same genes as the patient
67
Why are some people against stem cell research?
They feel embryos shouldn’t be experimented on as they are potential human lives
68
Why are some people for stem cell research?
They believe the suffering patient is more important than the rights of embryos
69
Where are plant stem cells found?
In the meristems
70
What can plant stem cells be used for?
Cloning a plant
71
Why is cloning a plant useful?
Can stop rare species being wiped out
72
What is diffusion?
The spreading out of particles from a high to a low concentration
73
Where can diffusion occur?
Solutions and gases
74
What is the concentration gradient?
The difference in concentration
75
The bigger the concentration gradient...
The faster the rate of diffusion
76
What else can increase the rate of diffusion?
High temperatures, make particles move quicker
77
How do substances move in and out of the cell?
Diffusion through the cell membrane
78
What type of molecules can diffuse through the cell membrane?
Small ones
79
What is osmosis?
Diffusion of water particles through a partially permeable membrane
80
What is active transport?
When substances move from a low to a high concentration, against the concentration gradient
81
What type of cell do we mainly associate with active transport?
Root hair cell
82
Why does active transport happen in root hair cells?
Because the plant needs the mineral ions from the soil but it often already has a higher concentration of them than the soil does
83
What does active transport require?
Energy
84
What is an exchange surface?
The surface has adapted to allow for easier diffusion
85
What are some properties of exchange surfaces?
Thing membranes, large surface areas, blood supply, ventilated
86
What are alveoli?
Little air sacs where gas exchange takes place
87
What diffuses out of the alveoli?
Oxygen
88
What diffuses into the alveoli?
Carbon dioxide
89
What are the three main properties of alveoli that maximise diffusion?
Enormous surface area, thin walls, good blood supply
90
What does the small intestine have to aid diffusion of digested food into the blood?
Villi
91
What are three main properties of the villi that maximise diffusion?
Large surface area, incredibly thin walls, good blood supply
92
What do leaves have to allow carbon dioxide, water vapour and oxygen to diffuse in and out?
Holes on the underneath called stomata
93
What are the stomata controlled by and why?
Guard cells, to prevent water being lost quicker than it is being replaced
94
What do fish have that allow carbon dioxide and water to diffuse in and out of their bloodstreams?
Gills
95
What do gills have that create a large surface area?
Gill filaments and lamellae

Biology GCSE AQA (5 decks)

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