B1 - Cell Biology Flashcards

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1
Q

What are three common features of plant and animal cells (eukaryotes)?

A
  1. Cell membrane
  2. Cytoplasm
  3. Genetic material in a nucleus
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2
Q

Which are bigger; bacterial cells (prokaryotes) or eukaryotes?

A

Eukaryotes.

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3
Q

True or false? “Prokaryotic cells have a cell wall.”

A

True

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4
Q

True or false? “Prokaryotic cells have a nucleus.”

A

False

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5
Q

In what form is the genetic material in a prokaryotic cell?

A

A single DNA loop.

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6
Q

Name five common parts of animal and plant cells.

A

Nucleus, cytoplasm, cell membrane mitochondria, ribosomes.

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7
Q

Name three features of only a plant cell.

A

Chloroplasts, permanent vacuole (filled with cell sap), cell wall.

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8
Q

Describe the function of the mitochondria.

A

Where aerobic respiration occurs to release energy.

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9
Q

Name three further features of a plant cell.

A

Chloroplasts, permanent vacuole (filled with cell sap), cell wall.

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10
Q

Describe the function of the cytoplasm.

A

The location of cellular reactions.

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11
Q

Describe the function of the cell membrane.

A

To determine what is allowed into and out of the cell.

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12
Q

Describe the function of the ribosomes.

A

To bond amino acids together to form proteins (protein synthesis).

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13
Q

Describe the function of the chloroplasts.

A

The location of photosynthesis.

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14
Q

Describe the function of the permanent vacuole.

A

A storage area for ions and water, sometimes pigments. Helps to maintain water balance.

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15
Q

Which strong material is the cell wall of plant and algal cells made from?

A

Cellulose

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16
Q

What is the definition of a cell?

A

The individual unit of an organism.

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17
Q

What is the definition of a tissue?

A

Cells of the same type working together to perform a specific function.

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18
Q

What is the definition of an organ?

A

A structure made from multiple tissue types to perform a specific function.

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19
Q

What is the definition of an organ system?

A

Multiple organs working together to perform a specific function.

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20
Q

Describe the specialisation of a sperm cell.

A

Mobile due to flagellum.
Many mitochondria to allow high energy release for movement.
Streamline head.
Digestive enzymes in the head to break down the eggs membrane.

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21
Q

Describe the specialisation of a nerve cell.

A

Many proteins embedded in the cell membrane to allow ion movement.
The nerve cell is covered with a fatty sheath which insulates the nerve cell and speeds up the nerve impulse.

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22
Q

Describe the specialisation of a muscle cell.

A

Many mitochondria to provide lots of energy for contractions.
Many ribosomes to synthesise proteins.

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23
Q

Describe the specialisation of a root hair cell.

A

Elongated shape to increase surface area for ion absorption.
Many mitochondria to provide lots of energy for active transport.

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24
Q

Describe the specialisation of a xylem cell.

A

Little cell contents to allow easy movement of water and ions through each cell.

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25
Q

What is cell differentiation?

A

The process where a stem cell develops new sub-cellular structures to let it perform a specific function.

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26
Q

When do most animal cells differentiate?

A

At an early stage of development.

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27
Q

In mature animals, what is cell differentiation used for?

A

Replacement of old/damaged cells.

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28
Q

What are the two advantages of electron microscopes over light microscopes?

A
  1. Increased magnification
  2. Increased resolution
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29
Q

What is the resolution of a microscope?

A

The ability to differentiate two or more objects close together.

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30
Q

What are the three forms of equation used to calculate magnification (M), the image size (I), or the actual size of an object (A)?

A

I = A X M
M = I / A
A = I / M

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31
Q

What is a contaminant?

A

An unwanted species of microorganism growing in your culture.

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32
Q

Define Eukaryotic cells.

A

A cell with a defined nucleus.

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33
Q

Define prokaryotic cells.

A

A cell without a nucleus.

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34
Q

What are the features of prokaryotic cells (bacteria)?

A

No nucleus, encased by a cell wall, pili helps to attach the cell to surfaces.

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35
Q

What are some disadvantages of using embryonic stem cells as a treatment?

A

Can cause viral infections.
Ethical beliefs.

36
Q

What material strengthens the wall of a xylem cell?

A

Lignin

37
Q

What part of the cell do most chemical reactions take place in?

A

Cytoplasm

38
Q

What came first prokaryotic or eukaryotic cells?

A

Prokaryotic cells, eukaryotic cells are the evolved versions of prokaryotic cells.

39
Q

What do prokaryotic cells not have?

A

Mitochondria
Chloroplasts
Nucleus, instead there’s genetic material stored in a single DNA loop in the cytoplasm.

40
Q

Define a prokaryote.

A

An organism made up of a single prokaryotic cell. (Unicellular organism)

41
Q

What are plasmids?

A

A single loop of DNA stored in the cytoplasm which contains most of the cells genetic information.

42
Q

What does the acrosome of the tip of the sperm cell contain?

A

Digestive enzymes needed to penetrate the egg cell.

43
Q

Define magnification.

A

How many times larger an image is when seen through a microscope compared to the actual object.

44
Q

Describe the shape of a red blood cell.

A

Biconcave disc.

45
Q

Do red blood cells have a nucleus?

A

NO.

46
Q

What is a chromosome?

A

A protein found in the nucleus of eukaryotic cells.
Which is a coiled thread-like structure of nucleic acids (DNA).

47
Q

What are genes?

A

Sections of DNA that contain the code for a particular protein.

48
Q

In what arrangement are chromosomes found normally?

A

Pairs

49
Q

How many chromosomes does a human have in each cell?

A

23 pairs OR 46 in total.

50
Q

What has to happen within the cell before Mitosis? (2 steps)

A
  1. Cell organelles (e.g. mitochondria and ribosomes) have to replicate
  2. Chromosomes have to be replicated (copied).
51
Q

How many chromosomes will be present in a cell after DNA replication?

A

92 OR 46 pairs.

52
Q

What occurs during cytokinesis (the final stage)?

A

The cytoplasm and cell membranes divide. Two daughter cells are created.

53
Q

Mitosis is critical for….

A

Growth, replacement and development of an organism.

54
Q

What is a stem cell?

A

Cells that have not undergone differentiation. aka. an undifferentiated cell.

55
Q

Describe the function of stem cells in embryos.

A

To develop into multiple cell types.
So that the embryo can develop into a mature organism.

56
Q

Describe the function of stem cells in plant meristems.

A

To allow a plant to keep growing throughout its life (animals stop growing when mature) by specialising into any type of cell.

57
Q

What is a potential use of stem cells in medicine?

A

To treat conditions where cells have been damaged e.g. diabetes, paralysis.

58
Q

Give an advantage of therapeutic cloning.

A

No rejection of the new cells by the patient (as they are the patient’s own genetic make-up).

59
Q

Give two potential problems with therapeutic cloning.

A
  1. Risk of viral infection
  2. Religious/ethical objections around the use of embryos.
60
Q

How are plant stem cells used in horticulture (commercial plant growing)?

A

To create plant cuttings (clones of the original plant).

61
Q

Give two advantages of the use of clones in horticulture.

A
  1. Rare species can be cloned to prevent extinction
  2. Crops with special adaptations (e.g. disease resistance) can be identically produced in large numbers.
62
Q

What happens during mitosis?

A

Two sets of chromosomes are pulled to opposite ends of the cell.
Nucleus divides in two.

63
Q

Why does yeast grow slowly at the start?

A

Cells are metabolising preparing for division.

64
Q

What is the difference between an embryonic stem cell and an adult stem cell?

A

Embryonic stem cells can differentiate into every type of cell. Whereas, adult stem cells cannot.

65
Q

What are the stages of the cell cycle called?

A

The Interphase, Mitosis, Cytokinesis

66
Q

What happens in the second stage of the cell cycle?

A

Mitosis - the nucleus divides

67
Q

What is therapeutic cloning?

A

Where stem cells are produced with the same genetic make-up as the patient

68
Q

What are the steps to carry out therapeutic cloning?

A
  1. Take a human egg cell from donor and discard the nucleus.
  2. Add the patients nucleus from their cell to the egg cell.
  3. The cell is stimulated to divide and will form an embryo.
  4. The stem cells from the embryo can then be cultured after 4-5 days.
69
Q

Define diffusion.

A

The net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient across a semi-permeable membrane.

70
Q

Name three substances which move by diffusion within animal cells.

A
  1. Oxygen
  2. Carbon dioxide in gas exchange
  3. Urea out of cells to be excreted from the body
71
Q

What three factors affect the rate of diffusion?

A
  1. The difference in concentrations (concentration gradient)
  2. Temperature
  3. Surface area of the membrane
72
Q

Does a single-celled organism have a high or low surface area: volume ration?

A

High

73
Q

How do single-celled organisms get enough oxygen without having lungs?

A

Due to its small size, and therefore its high SA:vol, diffusion across its membrane allows sufficient gas exchange.

74
Q

Why do multicellular organisms tend to need exchange surfaces and transport systems?

A

Low SA:vol, therefore cannot rely on diffusion across cell membranes.

75
Q

Name two common features that aid the exchange of substances in the small intestine, lungs and fish gills but also a plant roots and leaves.

A
  1. Large surface area
  2. Thin membrane to provide a short diffusion path
76
Q

Define osmosis.

A

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

77
Q

If an animal cell loses a lot of water, what happens?

A

It crenates (shrivels) and cellular reactions are slowed or stopped.

78
Q

If an animal cell gains a lot of water, what happens?

A

It can lyse (burst) and die.

79
Q

If a plant cell loses a lot of water, what happens?

A

It becomes plasmolysed (cell membrane shrinks away from the cell wall).

80
Q

If a plant cell gains a lot of water, what happens?

A

It becomes turgid (cell membrane pushes up against the cell wall).

81
Q

Define active transport.

A

The movement of substances from a low concentration to a high concentration (against a concentration gradient).

82
Q

What two things does active transport require that diffusion doesn’t?

A
  1. A transport protein (found in the cell membrane)
  2. Energy
83
Q

From what reaction does the energy required for active transport come?

A

Respiration.

84
Q

Where does active transport happen within a cell?

A

The mitochondria.

85
Q

Give two examples of where active transport is used in biology, (1 plant, 1 animal)

A
  1. Plant root hair cells absorbing mineral ions from the soil.
  2. Glucose absorption from the small intestine into the blood.
86
Q

Why does active transport require extra energy?

A

Goes against the concentration gradient.