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Biology Paper 1 > B1: Cells > Flashcards

B1: Cells Flashcards

1
Q

What are features of a light microscope?

A

Cheaper to make
Allow you to see the outline of cells
Uses light to form images
Living samples can be viewed
Low magnification
Low resolution

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2
Q

What are features of electron microscopes?

A

Can visualise finer details including organelles
Higher magnification
Higher resolution
Samples cannot be living
Use beam of electrons to form images
Expensive

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3
Q

What is the equation for magnification?

A

Magnification = image size / object (cell) size

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4
Q

How big are cells?

A

A few micrometers long
1 micrometer = 1x10^-6

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5
Q

How to you convert micrometers to mm?

A

Divide by 1000

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6
Q

Where is DNA found in eukaryotic cells?

A

In the nucleus

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7
Q

What are 2 examples of eukaryotic cells?

A

Animal cells
Plant cells

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8
Q

What are organelles?

A

Sub-cellular structures

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9
Q

Where is DNA in prokaryotic cells found?

A

A single loop of DNA
As plasmids (small loops of DNA)

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10
Q

What is an example of a prokaryotic cell?

A

Bacteria

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11
Q

What is the cell membrane?

A

Semi-permeable
Controls movement of substances in and out of a cell

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12
Q

What is the cell wall made of and what is it’s function?

A

Cellulose
Strengthens the cell

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13
Q

What takes place within the mitochondria?

A

Respiration to release energy

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14
Q

What is the function of ribosomes?

A

Site of protein synthesis

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15
Q

What are chloroplasts?

A

Made of chlorophyll that absorbs light energy for photosynthesis

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16
Q

What is stored within the permanent vacuole?

A

Cell sap

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17
Q

How do bacteria reproduce?

A

By binary fission
They divide every 10 minutes

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18
Q

How do we make cultures with aseptic technique?

A

-Lift lid of petri dish towards flame (to sterilise air by moving microbes away/killing them)
-Put drop of culture on agar/spread evenly
-Put drops/discs of antibiotics on culture if needed
-Few bits of tape (to allow aerobic respiration), incubate at 25 degrees celsius
-Measure size of cultures/areas with no bacteria with pi x r^2 or pi x d / 4

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19
Q

How many pairs of chromosomes do diploid cells have?

A

23

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20
Q

How many chromosomes are in gametes?

A

23

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21
Q

What is a haploid cell?

A

A cell with 23 singular chromosomes

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22
Q

Which process happens amongst cells for growth and repair?

A

Mitosis

23
Q

What is the process of mitosis?

A
  • Nucleus dissolves and genetic material is duplicated
  • The two sets of chromosomes move to different sides
  • Mitochondria, ribosomes & other organelles are duplicated
  • The cell divides, producing two genetically identical diploid cells
    (New nuclei are formed, or “the nucleus divides”)
24
Q

What are stem cells?

A

Cells that can specialise to perform specific functions. They are found in animal embryos and plant meristems

25
Q

Where are adult stem cells made?

A

In bone marrow

26
Q

What type of cell can adult stem cells differentiate into?

A

Blood cells

27
Q

What can embryo clones be used for?

A

To harvest stem cells
These can be used to treat conditions without them being rejected by the person’s body
Can differentiate into any type of specialised cell in the body

28
Q

What can cloning plants be used for?

A

To preserve species
To produce crops with desired traits

29
Q

What is diffusion?

A

The movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient) through a partially permeable membrane
This is passive as it requires no energy

30
Q

What is osmosis?

A

The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
This is a passive process

31
Q

How can the rate of diffusion and osmosis be increased?

A
  • Increasing the difference in concentrations (steeper concentration gradient)
  • Increasing the temperature
  • Increasing the surface area of the membrane
32
Q

What is the practical for osmosis?

A
  • Weigh, and place identical cylinders from a potato in sugar solutions of varying concentrations
  • After set time, remove excess water and reweigh
  • Calculate % change in mass = (final mass - initial mass / initial mass) x 100
  • Plot % change in mass against concentration. Using the line of best fit, the concentration at 0% change in mass is the same as inside the vegetable
33
Q

What is active transport?

A

The movement of particles from a more dilute solution to a more concentrated solution
This requires energy (from respiration), and so can move them against the concentration gradient

34
Q

What is the cytoplasm?

A

Jelly-like substance
Where chemical reactions happen

35
Q

What is the function of sperm cells?

A

To fertilise an ovum (egg)

36
Q

What are adaptations of sperm cells?

A
  • Tail to swim to the ovum and fertilise it
  • Lots of mitochondria to release energy from respiration, enabling the sperm to swim to the ovum
37
Q

What is the function of red blood cells?

A

To transport oxygen around the body

38
Q

What are adaptations of red blood cells?

A
  • No nucleus so more room to carry oxygen
  • Contains a red pigment called haemoglobin that binds to oxygen molecules
  • Flat bi-concave disc shape to increase surface area-to-volume ratio
39
Q

What is the function of muscle cells?

A

Contract and relax to allow movement

40
Q

What are adaptations of muscle cells?

A
  • Contains protein fibres, which can contract to make the cells shorter
  • Contains lots of mitochondria to release energy from respiration, allowing the muscles to contract
41
Q

What is the function of nerve cells?

A

Carry electrical impulses around the body

42
Q

What are adaptations of nerve cells?

A
  • Branched endings, called dendrites, to make connections with other neurones or effectors
  • Myelin sheath insulates the axon to increase the transmission speed of the electrical impulses
43
Q

What is the function of root hair cells?

A

Absorb mineral ions and water from the soil

44
Q

What are adaptations of root hair cells?

A
  • Long projection speeds up the absorption of water and mineral ions by increasing the surface area of the cell
  • Lots of mitochondria to release energy for the active transport of mineral ions from the soil
45
Q

What is the function of palisade cells?

A

Enable photosynthesis in the leaf

46
Q

What are adaptations of palisade cells?

A
  • Lots of chloroplasts containing chlorophyll to absorb light energy
  • Located at the top surface of the leaf where it can absorb the most light energy
47
Q

What are advantages of adult stem cells?

A
  • Fewer ethical issues - adults can consent to have their stem cells removed and used
  • An established technique for treating diseases such as leukaemia
  • Relatively safe to use as a treatment and donors recover quickly
48
Q

What are disadvantages of adult stem cells?

A
  • Requires a donor, potentially meaning a long wait time to find someone suitable
  • Can only differentiate into certain types of specialised cells, so can be used to treat fewer diseases
49
Q

What are advantages of embryonic stem cells?

A
  • Can treat a wide range of diseases as can form any specialised cell
  • May be possible to grow whole replacement organs
  • Usually no donor needed as they are obtained from spare embryos from fertility clinics
50
Q

What are disadvantages of embryonic stem cells?

A
  • Ethical issues as the embryo is destroyed and each embryo is a potential human life
  • Risk of transferring viral infections to the patient
  • Newer treatment so relatively under researched - not yet clear if they can cure as many diseases as thought
51
Q

What can plant meristems do?

A

Differentiate into all cell types - they can be used to create clones of whole plants

52
Q

What are advantages of plant meristems?

A
  • Rare species of plants can be cloned to prevent extinction
  • Plants with desirable traits, such as disease resistance, can be cloned to produce large numbers of identical plants
  • Fast and low-cost production of large numbers of plants
53
Q

What are disadvantages of plant meristems?

A
  • Cloned plants are genetically identical
  • A whole crop is at risk of being destroyed by a single disease or genetic defect
54
Q

What is the process of therapeutic cloning?

A
  • Cells from a patient’s body are used to create a cloned early embryo of themselves
  • Stem cells from this embryo can be used for medical treatments and growing new organs
  • These stem cells have the same genes as the patient, so are less likely to be rejected when transplanted

Biology Paper 1 (4 decks)

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