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Biology > B1 - Cell Biology > Flashcards

B1 - Cell Biology Flashcards

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1
Q

What are the two types of cell?

A

Eukaryotic and prokaryotic

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2
Q

Compare eukaryotic and prokaryotic cells

A

Eukaryotes contain membrane-bound organelles and a nucleus

Prokaryotes have genetic information as single DNA loops, enclosed in plasmids or free floating in the cytoplasm

Both make up living things

Eukaryotic cells divide by mitosis

Prokaryotic cells divide by binary fission

Eukaryotes are larger than prokaryotes

Both contain a cell wall in plants, cytoplasm and ribosomes

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3
Q

What is order of magnitude?

A

A power to the base 10 used to quantify and compare size

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4
Q

What is the function of the nucleus?

A

Controls and regulates cell activity. Contains the genetic material.

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5
Q

What is the function of the cytoplasm?

A

The site where chemical reactions occur

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6
Q

What is the function of the cell (plasma) membrane?

A

Regulates the cell’s biochemistry; what substances enter and leave the cell

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7
Q

What is the function of the mitochondria?

A

Site of aerobic respiration, which releases energy in the form of ATP

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8
Q

What is the function of ribosomes?

A

Site of protein synthesis

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9
Q

What is the function of the cell wall?

A

Made of cellulose. Provides strength and prevents the cell from bursting due to osmotic stress

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10
Q

What is the function of the permanent vacuole?

A

Supports the cell by regulating water balance, maintaining its turgidity. Contains cell sap

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11
Q

What is the function of the chloroplasts?

A

The green pigment chlorophyll in the chloroplast absorbs light energy for photosynthesis

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12
Q

How are sperm cells adapted to their function?

A

Acrosome in the head, which allows for the cell to penetrate the outer membrane of the ovum for fertilisation

High yield of mitochondria for movement

Haploid nucleus, which contains the genetic information

Tail and stream-lined body for movement

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13
Q

How are nerve cells adapted to their function?

A

Long axons, which allow for electrical impulses to be transmitted rapidly all over the body from the CNS

Dendrites to connect with other neurones, forming a complex network

Axon is covered with a fatty Myelin Sheath, which speeds up nerve impulses

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14
Q

How are muscle cells adapted to their function?

A

High yield of mitochondria so that the muscle can contract and relax

Protein fibres that allow them to slide over each other to produce muscle contraction

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15
Q

How are root hair cells adapted to their function?

A

Large surface area for water and mineral absorption by osmosis or active transport

Thin walls so that water absorption is not restricted

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16
Q

What is cell differentiation?

A

When cells become specialised to perform a particular function

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17
Q

Why is cell differentiation important?

A

Allows for the production of various tissues and organs that perform different functions in the human body

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18
Q

At what point in their life cycle do most animal cells differentiate?

A

Early in their life cycle

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19
Q

How long do plant cells retain the ability to differentiate?

A

Throughout their entire life cycle

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20
Q

What is the purpose of cell division in mature animals?

A

Repair and replacement of cells

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21
Q

What changes does a cell undergo as it differentiates?

A

Acquires different sub-cellular structures to adapt the cell to perform a particular function

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22
Q

Advantages of light microscopes? (4)

A
  • Portable
  • Affordable/cheaper
  • Easy to use
  • Observe living and dead specimens
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23
Q

What are two disadvantages of using light microscopes?

A

Limited resolution and magnification

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24
Q

What are two advantages of electron microscopes?

A

Greater magnification and resolution

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25
Q

Why do electron microscopes have a greater magnification and resolution?

A

Use a beam of electrons, which have a shorter wavelength than photons of light

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26
Q

Why are electron microscopes more efficient for scientists?

A

Allows for sub-cellular structures to be observed in detail and hence, derive explanations as to why structure relates to function

27
Q

Disadvantages of electron microscopes? (4)

A
  • Expensive
  • Less portable
  • Require training to use
  • Only dead specimens can be observed
28
Q

Magnification equation

A

Magnification = image size/actual size

Remember I AM

29
Q

How do bacteria multiply?

A

Binary fission

30
Q

How often do bacteria multiply?

A

Once every 20 mins IF enough nutrients are available and the temperature is suitable for growth

31
Q

What two ways can bacteria be grown?

A

Using a nutrient broth solution

As colonies on an agar gel plate

32
Q

What are uncontaminated cultures of microorganisms needed for?

A

Investigating disinfectant and antibiotic action

33
Q

Design a method for the preparation of an uncontaminated culture using aseptic technique (6)

A
34
Q

Why must petri dishes and culture media be sterilised before use?

A

To kill any bacteria/microbes that are present already

35
Q

Why must inoculating loops be sterilised by passing them through a Bunsen Burner flame?

A

To kill any bacteria/microbes present already

36
Q

Why must a Petri dish be secured with tape and stored upside down? (3)

A

Stops bacteria/microbes in the air contaminating the culture

Lid is not fully sealed to prevent the growth of anaerobic bacteria

Upside down to prevent condensation from forming and dripping down onto the colonies

37
Q

Why are cultures incubated at 25C in school laboratories?

A

Harmful pathogens are less likely to grow at this temperature

38
Q

What is the formula used to calculate cross-sectional areas of colonies or clear areas around colonies?

A

𝝅 r 2

radius = diameter/2

39
Q

How would you calculate the number of bacteria in a population after a certain time if given the mean division time?

A
40
Q

M —> cm —-> mm —> picometre —> nanometre

A

X100
X10
X1000
X1000

41
Q

What is the function of:

  • Sperm cells
  • Muscle cells
  • Nerve cells
  • Root hair cells
A

The function of sperm cells is reproduction; to fertilise the ovum

The function of muscle cells is contraction

The function of nerve cells is to carry electrical signals from one part of the body to another

The function of root hair cells is to absorb water and mineral ions

42
Q

What is the function of phloem tissue?

A

Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. This is otherwise known as translocation

43
Q

What is the function of xylem tissue?

A

Transports water and mineral ions from the roots to the stem and leaves

44
Q

How is the phloem adapted to its function?

A
45
Q

How is the xylem adapted to its function?

A
46
Q

Define the following terms:

  • Culture medium
  • Agar jelly
  • Inhibition zone
A

A culture medium is liquid/gel substance that contains nutrients in which microorganisms, cells and tissues are grown

Agar jelly is a substance that helps feed and grow bacteria

Inhibitions zone is a clear area left where the bacteria have been killed by the antibiotic. Bigger zone means the antibiotic is more effective

47
Q

Explain how the shape of the red blood cells in a person with sickle cell disease could affect how much oxygen reaches their muscles

A

Red blood cells carry oxygen
Red blood cells contain haemoglobin, which binds to oxygen
A person with sickle cell has smaller RBCs, so they contain less haemoglobin and less oxygen is carried
It has a smaller surface area to volume ratio, so diffusion is slower and so less oxygen is delivered per minute

48
Q

Compare the processes of diffusion, active transport and diffusion

A
49
Q

Scientists have developed patches of beating heart cells to repair damaged heart tissue

The patches are placed onto areas of the heart where cells have died. New cells grow to replace the dead cells. The patches are made using a person’s own cells that are converted into stem cells.

Explain why stem cells are used to make the patches

A

Stem cells are undifferentiated cells

So they can differentiate to form heart cells

50
Q

Describe a method to investigate the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition

A

Clean bench with disinfectant to kill microorganisms

Sterilise inoculating loop to prevent contamination

Place sterile agar gel plate near Bunsen burner to kill bacteria

Use inoculating loop to spread bacteria evenly over the plate

Place sterile filter paper disks soaked in chosen antibiotic. Use a paper disk soaked in water as a control to ensure the inhibition zones are due to the effects of the antibiotics alone

Store the plate with adhesive tape, upside down

Leave the plate for 48 hours at 25C

Measure the zone of inhibition using the equation of the area of a circle and use this to compare the effectiveness of the antibiotics/antiseptics

51
Q

Define cell cycle

A

Series of stages in which a cell divides

52
Q

How many chromosomes does the human body contain?

Describe the stages of mitosis

A

Human body cells contain 23 pairs of chromosomes

  1. DNA replicates to form two copies of each chromosome. The number of sub-cellular structures increases
  2. One set of chromosomes is pulled to each end (poles) of the cell (by the use of spindle fibres). The nucleus divides to form two nuclei
  3. In cytokinesis the cytoplasm and cell membrane divide to form two genetically identical daughter cells
53
Q

What is a stem cell?

A

Undifferentiated cell which can give rise to many more cells of the same type and differentiate into certain other cells

54
Q

How can stem cells from human embryos be used?

A

Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells

55
Q

How can stem cells from adult bone marrow be used?

A

Stem cells from adult bone marrow can differentiate and form many types of cells, including blood cells

56
Q

How can meristem tissue be used?

A

Meristem tissue can differentiate into any type of plant cell throughout the life of the plant

57
Q

What are two examples of treatments that stem cells can give rise to?

A

They may be able to help in conditions such as diabetes and paralysis

58
Q

What is therapeutic cloning?

A

Producing an embryo with the same genes as the patient

Stem cells from embryo is then simulated to divide to form any cells the patient needs for medical treatment.

59
Q

What is the advantage of therapeutic cloning?

A

Stem cells are unlikely to be rejected by the patient’s immune system

60
Q

What are some issues associated with the use of stem cells in medicine?

A

Viral infections may be transferred

risk of rejection by the immune system, so patients have to take immunosuppressants drugs

Ethical and religious objections, for example, potential life is destroyed and the embryo cannot give consent

61
Q

Describe the stem cells in plants

A

Meristem tissue is found in meristem regions in roots and shoots tips

This can differentiate into any type of plant cell throughout of plants lifetime

62
Q

How can stem cells from meristems in plants be used?

A

Rare species can be cloned to protect from extinction

Crop plants with special features, such as disease resistance, can be cloned to produce large numbers of identical plants for farmers

63
Q

What are the factors affecting the rate of diffusion?

A

Concentration, surface area and temperature

64
Q

Describe how to prepare and observe a microscope to view cells

A

Peel off thin layer of tissue using forceps and place a drop of water on the slide/swab inside cheek with a cotton bud and smear into the centre of the slide

Add a drip of stain with a pipette and lower coverslip at an angle without trapping air bubbles

Clip slide onto the stage and turn on the light

Select the lowest power objective lens

Use coarse focusing dual to move stage close to the lens
Turn the coarse focusing dial to move stage away from the lens until image comes into focus

Adjust fine focusing wheel to get a clear image, swap to a higher power objective lens and refocus

Biology (9 decks)

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