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Biology > B1-Cell biology > Flashcards

B1-Cell biology Flashcards

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1
Q

What are the 2 types of microscopes?

A

Light and Electron

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2
Q

1) What is the formula for magnification?
2) How do you calculate it from the eyepiece lenses?

A

1) Size of image /size of real object
2) You would multiply the magnification of the eyepeice and objective lenses

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3
Q

What is resolution?

A

The ability to distinguish between 2 points

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4
Q

How many times more can electron microscopes magnify than light microscopes?

A

1000x

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5
Q

What does the symbol μm mean and how many times smaller is it than a mm?

A

Micrometre-1000x smaller

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6
Q

What does the symbol nm mean and how many times smaller is it than a mm?

A

Nanometre-1,000,000x smaller

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7
Q

What are the pros and cons of a light microscope?

A

Pros: Cheap, Portable, Produces images in colour, Can veiw live specimens
Cons: Low resolution and magnification

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8
Q

What are some pros and cons of an electron microscope?

A

Pros: High resolution and magnification, Can veiw in 3D
Cons: Expensive, Large, Not portable, Black and white images, Can’t veiw live specimens

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9
Q

What organelles (sub-cellular structures) do animal cells contain?

A
  • The Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
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10
Q

What organelles (sub-cellular structures) do plant cells contain?

A
  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
  • Chloroplasts
  • Cell wall
  • Permanent vacuole
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11
Q

What is the function of the nucleus?

A

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

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12
Q

What is the function of the cytoplasm?

A

It contains all of the other organelles are suspended and is where most of the chemical reactions take place

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13
Q

What is the function of the cell membrane?

A

Its structure is semi-permeable and controls the movement of substances in and out of the cell

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14
Q

What is the function of the mitochondria?

A

It contains enzymes for aerobic respiration-‘the powerhouse of the cell’

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15
Q

What is the function of the ribosomes?

A

It is where protein synthesis takes place

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16
Q

What is the function of the chloroplasts?

A

They contain the green pigment, chlorophyll which absorbs light energy for photosynthesis. It also containes enzymes needed for photosynthesis

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17
Q

What is the function of the cell wall?

A

Made from cellulose fibres it strengthens the cell and supports the plant

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18
Q

What is the function of the permanent vacuole?

A

It is filled with cell sap to keep the cell turgid

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19
Q

What are eukaryotic cells?

A

Cells that have a cell membrane, mitochondria and genetic material that is enclosed in a nucleus-a cell with a nucleus

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20
Q

What are prokaryotic cells?

A

Cells that consist of cytoplasm and a cell membrane surrounded by a cell wall-the genetic material is not in a distinct nucleus

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21
Q

What is an example of a eukaryote?

A

Plant and animal cells

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22
Q

What is an example of a prokaryote?

A

Bacteria

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23
Q

What is the structure of a bacterial cell?

A

A singular loop of DNA and loops of DNA called plasmids surrounded by a cell membrane, cell wall and a slime capsule. Also, flagella are connected to the bacteria which help the cell move.

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24
Q

What is the size order of the following from largest to smallest?
Prokaryotes, Viruses, Eukaryotes,

A

Eukaryotes, Prokaryotes, Viruses

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25
Q

List 7 specialised cells

A
  • Nerve cells
  • Muscle cells
  • Sperm cells
  • Root hair cells
  • Photosynthetic cells
  • Xylem cells
  • Phloem cells
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26
Q

How are nerve cells adapted to their function?

A
  • They have lots of dendrites to make connections to other nerve cells
  • They have an axon that carries the nerve impulse from one place to another-these can be very long-up to 1m in the human body
  • The nerve endings called synapses have adaptations to pass the impulses to another cell using special transmitter chemicals
  • They have fatty insulation called a myelin sheath to maintain make sure none of the electrical impulses are lost
  • They contain lots of mitochondria to provide the energy needed to make the tranmitter chemicals
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27
Q

How are muscle cells adapted to their function?

A
  • They contain special proteins that slide past each other making the fibres contract
  • They contain many mitochondria to transfer the energy needed for the chemical reactions to take place
  • They can store glycogen, a chemical that can be broken down and used in cellular respiration by the mitochondria
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28
Q

How are sperm cells adapted to their function?

A
  • They have a long tail that helps the sperm swim to the egg
  • The middle section is full of mitochondria to transfer the energy needed for the tail
  • The acrosome (head) stores digestive enzymes for breaking down the outer layers of the egg
  • They contains half the genetic information to be passed on
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29
Q

How are root hair cells adapted to their function?

A
  • They have a very large surface area to volume ratio for water to move into the cell
  • They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil to the cell
  • They have any mitochondria that transfer the energy needed for the active transport of mineral ions into the root hair cells
30
Q

How are photosynthetic cells adapted to their function?

A
  • They contain chloroplasts containing chlorophyll to trap the light needed for photosynthesis
  • They are usually positioned in continous layers on the outside of the leaves so they absorb as much light as possible
  • They have a large permanent vacuole-this helps keep the cells rigid as a result of osmosis-this helps suport the stem and keep the leaf spread out
31
Q

How are xylem cells adapted to their function?

A
  • They are still alive when first formed and a special chemical called lignin builds up in spirals in the cell walls-after the cell dies hollow tubes are formed to allow water and mineral ions to move easily through them
  • The spirals and rings of lignin in the xylem cells make them strong and help then withstand the pressure of water moving up the plant-they also help support the plant stem
32
Q

How are phloem cells adapted to their function?

A
  • The cell walls between the cells break down to form special sieve plates-this allows water carrying dissolved food to move freely up and down the tubes
  • Phloem cells are supported by companion cells to keep them alive
33
Q

Define the Nucleus

A

The part of the cell that contains genetic information

34
Q

Define Chromosomes

A

Thread like structures holding genes

35
Q

1)Define DNA
2)What does DNA stand for?

A

1) The chemical from which chromosomes are made
2) Deoxyribonucleic acid

36
Q

Define a cell

A

The basic building block of a living organism

37
Q

What is the cell division in the cell cycle know as?

A

Mitosis

38
Q

What is stage 1 of the cell cycle?

A

The cells grow bigger, replicate their DNA to form copies of each chromosome ready for cell division, and the number of sub-cellular organisms such as mitochondria and ribosomes increase

39
Q

What is stage 2 of the cell cycle?

A

Mitosis-the two sets of chromosomes are pulled to the oposite ends of the cell and the nucleus divides

40
Q

What is stage 3 of the cell cycle?

A

The cytoplasm and the cell membranes divide to form 2 daughter cells

41
Q

What is cell differentiation?

A

Where a cell changes to become specialised for a particular job

42
Q

What are stem cells?

A

Cells that haven’t yet been differentiated

43
Q

What are the 2 types of human stem cells?

A

Adult stem cells and embryonic stem cells

44
Q

Where can you find embryonic stem cells?

A

In human embryos

45
Q

Where are adult stem cells found?

A

In the:
* brain
* eyes
* blood
* heart
* liver
* bone marrow
* skin
* muscle

46
Q

Why are embryonic stem cells better than adult stem cells?

A

They can develop into any cell type unlike adult stem cells which can only develop into certain cell types

47
Q

What are plant stem cells called?

A

Meristem cells

48
Q

Where are plant stem cells found?

A

In the meristems of the plant-close to the tip of the shoot and the tip of the root

49
Q

How can cells from meristems in plants be cloned?

A

Tissue samples can be scraped from plants and grown in a culture medium as well as nutrients and plant hormones to stimulate growth and division

50
Q

What diseases can embryonic stem cells treat?

A
  • Type 1 diabetes
  • Multiple sclerosis
  • Spinal cord or brain injuries
51
Q

What diseases can adult stem cells treat?

A

Bone marrow transplants in cases of blood cell cancer or to replace white blood cells destroyed by cancer treatment

52
Q

What is Therapeutic cloning?

A

Therapeutic cloning is where a human egg cell has a nucleus replaced by one of the patient’s own. Then the cell is stimulated to divide and develops into an embryo. After 4-5 days stem cells are removed from the embryo. This means that as a result of having the same DNA of the patient, the stem cells can’t be rejected by the body.

53
Q

What are the clinical issues with using stem cells in medicine?

A
  • There is no guarantee how successful these therapies will be
  • It is currently difficult to find suitable stem cell donors
  • The difficulty in obtaining and storing a patient’s enbryonic stem cells
  • Mutations have been observed in stem cells cultured for a number of generations-this can cause cancerous cells
  • Cultured stem cells could be contaminated with viruses
54
Q

What are the ethical issues with using stem cells in medicine?

A
  • Is it right to destroy human embryos?
  • Embryos could be veiwed as a commodity and not as an embryo that could develop into a person
  • At what stage of its development should an embryo be regarded as, and treated as a person?
  • A source of embryonic stem cells is unused embryos produced by IVF
55
Q

What are the social issues with using stem cells in medicine?

A
  • Educating the public on the uses of stem cells is important
  • Whether the benefits outweigh the objections
  • Much of the research is being carried out by commercial clinics so reported successes are not subject to peer review
  • Patients could be exploited by paying for expensive treatments and being given false hope of a cure
56
Q

What is it called when particles in a liquid and a gas move from an area of high to low concentration?

A

Diffusion

56
Q

What is it called when particles in a liquid and a gas move from an area of high to low concentration?

A

Diffusion

57
Q

What is the definition of diffusion?

A

The net movement of particles from a high to a low concentration?

58
Q

What 4 factors increase diffusion?

A
  • A higher temperature
  • A larger surface area
  • Smaller particles
  • A larger concentration gradient
59
Q

What substances diffuse in our body?

A

Carbon dioxide, Oxygen, Glucose, Urea

60
Q

What is the definition of osmosis?

A

Osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane.

61
Q

What causes osmosis?

A

Differences in the concentrations of solution inside and outside a cell

62
Q

What 3 stages would a plant cell go through if it was placed in an increasingly more concentrated solution?

A
  • Turgid
  • Flaccid
  • Plasmolysed
63
Q

Finish the sentences:

If the concentration of solutes in the solution around the cell is the same as the internal concentration, the solution is ……………….. to the cell.
If the concentration of solutes in the solution around the cell is higher as the internal concentration, the solution is ……………….. to the cell.
If the concentration of solutes in the solution around the cell is lower as the internal concentration, the solution is ……………….. to the cell.

A

1) isotonic
2) hypertonic
3) hypotonic

64
Q

Why does osmosis have a drastic effect on animal cells?

A

There is no cell walls meaning that the animal cells have the potential to swell up and burst or shrivel up and die

65
Q

What is active transport?

A

Active transport is where minerals and nutrients move from a low to a high concentration gradient

66
Q

Why is energy needed for active transport?

A

Energy is needed to carry a molecule across the membrane and to then return to its original position

67
Q

What are 3 examples of active transport taking place?

A
  • Mineral ions moving from the soil into a plant
  • Salt transported out of the body into the sea in some marine animals
  • Sugar molecules to be absorbed by the gut
68
Q

What does an effective exchange surface need to have for effective exchange?

A
  • A large surface area to volume ratio
  • A thin membrane
  • A high concentration gradient
69
Q

Fill in the blanks:

As an organism gets bigger the surface area to volume ratio ……………….. .

A

Decreases

70
Q

How do larger organisms get around not having a large surface area to volume ratio?

A

By having specific transport systens-such as the circulatory system

Biology (7 decks)

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