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Biology GCSE > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What are the two different types of cells?

A

Eukaryotic cells and prokaryotic cells.

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2
Q

Where can you find eukaryotic cells?

A

Plants, animals, fungi and protists e.g sequoia trees

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3
Q

Where can you find prokaryotic cells?

A

Bacteria e.g E. coli

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4
Q

How big are the different types of cells?

A

Eukaryotic cells are 10 - 100 micrometres, prokaryotic cells are 0.1 - 5.0 micrometres.

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5
Q

What sub-cellular structures can be found in a prokaryotic cell?

A

A single DNA loop in the cytoplasm that stores genetic material, plasmids and a cell membrane.

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6
Q

What are plasmids?

A

Small rings of DNA in prokaryotic cells that can replicate and move between cells to share genetic information.

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7
Q 
1 km = 1 kilometre = ?m
1 cm = 1 centimetre = ?m
1 mm = 1 millimetre = ?m
1 µm = 1 micrometre = ?m
1 nm = 1 nanometre = ?m
A 
km = 1000m
cm = 0.01 m
mm = 0.001 m
µm  = 0.000001m
nm = 0.000000001 m
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8
Q

What is the job of a cell membrane?

A
  • The cell membrane separates the interior (inside) of the cell from the environment outside.
  • This membrane is selectively permeable. This means that it has control over which substances enter and exit the cell.
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9
Q

What is the job of a nucleus?

A
  • The nucleus is the control centre of the cell.

- It contains chromosomes (which contain the cell’s genetic material).

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10
Q

What is the job of a ribosome?

A

-Ribosomes are responsible for synthesising (making) proteins.

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11
Q

What is the job of mitochondria?

A
  • Mitochondria are the organelles where aerobic respiration happens.
  • Aerobic respiration is a process that uses sugar and oxygen to release energy. So, it is our mitochondria that produce the energy our cells need to function.
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12
Q

What is the job of cytoplasm?

A
  • Cytoplasm is a jelly-like fluid that fills the cell.

- It is where most of the cell’s chemical reactions take place.

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13
Q

What is a permanent vacuole?

A
  • A permanent vacuole is a fluid-filled sac that stores water.
  • It is enclosed in a membrane (a wall that substances can pass through).
  • It can make up as much as 90% of a plant cell’s volume.
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14
Q

What are chloroplasts?

A

-Chloroplasts contain chlorophyll, which is needed for the process of photosynthesis.

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15
Q

What is a cell wall?

A
  • The cell wall surrounds the cell and is made of cellulose.

- The cell wall increases the structural strength of the cell.

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16
Q

What is cell differentiation?

A

When a cell acquires different sub-cellular structures and creates new tissues to let it perform a specific function. Primarily happens during organism’s development.

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17
Q

How is cell differentiation different in animals and plants?

A
  • In plants, cell differentiation happens throughout their lives.
  • In animals, cell differentiation happens in the early stages of their lives (embryo). Cell division occurs in mature animals to replace/repair original tissues.
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18
Q

What are the sub-cellular structures of bacterial cells?

A

Cytoplasm, plasmids, flagella, cell wall + membrane.

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19
Q

How are sperm cells specialised?

A

-The middle section is filled with mitochondria to provide the sperm with the energy it needs to travel a long distance to reach the egg cell.
-The acrosome is found at the tip of the head. It contains the digestive enzymes needed to penetrate (break into) an egg cell.
-The flagellum (‘tail’) is used for the cell’s motion. This allows sperm cells to travel towards the egg cell.
-The ‘head’ contains the sperm cell’s nucleus. The nucleus carries one half of an organism’s genetic material.
This combines with the egg cell’s half of genetic material to fertilise the egg cell.

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20
Q

How are nerve cells specialised?

A

-Nerve cells have a long axon which is how the electrical signal travels. This increases the distance that electrical signals can travel.
-A sheath made of a material called myelin surrounds the axon of the nerve cell. This stops the electrical nerve signals leaking out of the nerve cell.
This increases the speed of transmission (travel) of electrical signals.
-Several dendrites spread outwards from the cell body to transfer electrical messages to other neurons.

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21
Q

How are muscle cells specialised?

A
  • A muscle cell contains lots of mitochondria to generate lots of energy for motion.
  • Protein fibres within the cell can contract, allowing the muscle to move.
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22
Q

How are root hair cells specialised?

A
  • Root hair cells are specialised to increase the efficiency of water absorption and the uptake of minerals required for the plant’s survival.
  • These cells are located underground and so do not contain chloroplasts (there is no light for photosynthesis).
  • Root hair cells are long projections that increase the surface area that the plant can use to absorb water and minerals.
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23
Q

How are xylem cells specialised?

A

-Xylem vessels are made up of a series of connected dead xylem cells.
The end walls of the dead cells are broken to allow water to move through
-Lignin (a substance) strengthens the cell walls of xylem cells.

24
Q

How are phloem cells specialised?

A

The end walls of phloem cells contain small holes to allow food products to move up and down the phloem vessels throughout the plant.

25
Q

What is the function of the phloem and xylem?

A

To transport sugars, minerals and water around the plant.

26
Q

When using microscopes, what are the two most important variables?

A

Magnification and resolution.

27
Q

What is the equation for magnification?

A

Magnification = image size/real size

28
Q

What are the differences between light and electron microscopes?

A

-Electron microscopes work in a similar way to light microscopes. However, electrons are passed through the specimen instead of light.
They can now resolve distances of 1nm (better resolution) with magnifications of ×500,000.
-The high level of detail of electron microscopes allowed scientists to see sub-cellular structures more clearly.

29
Q

What are cultures of microorganisms?

A

Microorganisms grown in a lab that can be used to investigate the effects of antibiotics and disinfectants, which both kill bacteria.

30
Q

What are the different ways in which microorganisms can be cultured?

A

An agar gel plate and a nutrient broth (containing carbohydrates as an energy source).

31
Q

What are some of the possible consequences of contamination?

A

Investigation becomes invalidated and harmful bacteria grow.

32
Q

Where are chromosomes found and what do they do?

A

Chromosomes, found in cell nuclei, are made up of many different genes that encode (produce) many different proteins.

33
Q

What are the three main stages of the cell cycle?

A

1) Initial growth stage
2) Mitosis
3) Cell division

34
Q

How can we use microscopy to study the cell cycle?

A
  • Microscopes allow us to see things we can’t with the naked eye.
  • By culturing cells and then viewing them at a high resolution under a microscope, we can identify different cells in different stages of the cell cycle.
35
Q

Why is it important that the daughter cells have the same chromosomes as each other?

A

Some processes require identical cells to be produced, for example the growth and repair of tissues and asexual reproduction.

36
Q

What are stem cells?

A

-Stem cells are undifferentiated cells that have not yet specialised to perform a specific function.

37
Q

Where can stem cells be found?

A
  • In human adults, stem cells can be found in bone marrow (as well as other tissues and organs).
  • Plant stem cells are found in the meristem tissue.
38
Q

What are uses of stem cells?

A
  • Stem cells may be able to replace damaged cells in the body.
  • Plant stem cells can help us quickly and cheaply produce cloned plants.
  • Therapeutic cloning.
39
Q

Disadvantages of stem cells in medical treatments:

A
  • Viral infections

- Ethical beliefs

40
Q

What is the difference between diffusion and osmosis?

A

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration through a cell membrane however osmosis is specifically the movement of water particles through a partially permeable membrane from an area of low concentration to high concentration.
Both are PASSIVE transport methods.

41
Q

What factors affect the rate of diffusion?

A
  • Membrane surface area
  • Temperature
  • Concentration gradient
42
Q

Why do small organisms normally have higher surface area to volume ratios than large organisms?

A

Diffusion can happen through a large area in small organisms. This makes diffusion useful for transporting molecules through a small organism.

43
Q

How can exchange surfaces be adapted?

A
  • A thin membrane reduces the diffusion distance.
  • Ventilation to maintain a high concentration gradient and increase the rate of exchange.
  • Densely packed blood vessels to replenish the blood supply to maintain a high concentration gradient by bringing in new blood as diffusion starts to even out the concentrations.
44
Q

What are examples of exchange surfaces?

A
  • Small intestines
  • Lungs
  • Gills
  • Roots
45
Q

How does water move in osmosis?

A

In both directions, but the net movement is from dilute to concentrated.

46
Q

What is an independent and dependent variable?

A

The independent variable is what is controlled and varied throughout an experiment while the dependent variable is what is measured.

47
Q

Describe active transport:

A

Active transport is the net movement of particles against a concentration gradient.
This means that energy is needed for active transport to happen.

48
Q

What products kill bacteria?

A

Antibiotics and disinfectants.

49
Q

What are potential sources of contamination for harmful bacteria that could grow?

A
  • Skin
  • Water
  • Air
  • Soil
50
Q

How is contamination prevented?

A

Through aseptic techniques (killing and preventing entry of unwanted bacteria).

51
Q

What are examples of aseptic techniques?

A

Temperature, boiling and flame (sterilisation).

52
Q

How do bacteria multiply?

A

Binary fission.

53
Q

What happens in the first stage of the cell cycle?

A

Interphase (growth) is where extra sub-cellular structures are produced and the cell’s chromosomes are replicated so that there are two sets of them.

54
Q

What happens in the second stage of the cell cycle?

A

Mitosis where the two sets of chromosomes are pulled to opposite ends of the cell. Then, the nucleus divides into two.

55
Q

What happens in the third stage of the cell cycle?

A

Cytokinesis is where the cytoplasm and cell membranes are divided resulting in the production of two identical cells.

56
Q

How can the three types of stem cells differentiate:

  • embryonic stem cells
  • human adult stem cells
  • plant stem cells
A

-Embryonic stem cells can differentiate into most cell types, to produce all of the cell types that will make up the organism.
Human adult stem cells differentiate into fewer cell types than stem cells in embryos. They are used to replace dying cells and damaged tissues.
-Plant stem cells differentiate throughout their lives.

57
Q

What is therapeutic cloning?

A

It is a process that produces an embryo with genes that are identical to the patient’s.
Stem cells taken from this embryo will have the same DNA as the patient.
This means that the patient’s body will not reject the stem cells or body cells made from the embryo’s stem cells.

Biology GCSE (2 decks)

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