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Cell biology Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is the difference between eukaryotic and prokaryotic cells?

A

Eukaryotic cells are complex and have a nucleus
Prokaryotic cells are simpler and smaller

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2
Q

What is a eukaryote?

A

An organism made up of eukaryotic cells

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3
Q

Name all the organelles in an animal cell

there are 5

A

1. Nucleus
2. Cytoplasm
3. Cell membrane
4. Ribosomes
5. Mitochondria

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4
Q

Name all the extra organelles in a plant cell

not including those in an animal cell

A

1. Cell wall
2. Permanent vacuole
3. Chloroplasts
4. + those in an animal cell

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5
Q

What is a prokaryote and an example

A

It is a prokaryotic cell (single-celled organism)
Example: bacteria

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6
Q

Name the organelles in a bacterial cell

A

1. Cytoplasm
2. Cell membrane
3. Cell wall
4. Plasmids
5. Single strand of DNA

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7
Q

Name the 2 types of microscopes

A

Light microscopes
Electron Microscopes

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8
Q

How do electron microscopes work? What do they let us see?

A

They use electrons to form an image. They have much higher magnification and resolution.
They let us see smaller things in more detail (e.g. internal structure of mitochondria)

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9
Q

How do light microscopes work? What can they let us see?

A

They use light and lenses to form an image of a specimen and magnify it.
They let us see individual cells and large subcellular structures (e.g. nuclei)

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10
Q

What is the formula for magnification?

A

magnification = image size / real size

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11
Q

How do you prepare a slide for onion cells?

A
  1. Add a drop of water to the middle of a clean slide
  2. Cut up an onion + seperate its layers. Use tweezers to peel off some epidermal tissue from the bottom of one of the layers
  3. Using the tweezers, place the epidermal tissue into the water on the slide
  4. Add a drop of iodine solution (a stain) which will highlight the object
  5. Place a cover slip on top. Try to avoid air bubbles - they’ll obstruct the view.
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12
Q

How do you use a light microscope to observe a slide?

A
  1. Clip the slide onto the stage
  2. Select the lowest-powered objective lens
  3. Adjust mirror and turn on the light
  4. Use the coarse adjustment knob to move the stage up to just below the objective lens
  5. Slide must not touch lens
  6. Look down eyepiece. Use coarse adjustment knob to move stage downwards until the image is roughly in focus
  7. Adjust focus with fine adjustment knob, until you get a clear image,
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13
Q

How do you work out the total visual magnification from a microscope?

A

magnification of objective lens x magnification of eyepiece = total visual magnification

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14
Q

Define differentiation

A

the process by which a cell changes to become specialised for its job

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15
Q

Can cells always differentiate?

A

most animal cells lose the ability at an early stage
most plant cells retain the ability to differentiate throughout their life

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16
Q

What is an undifferentiated cell called?

A

stem cell

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17
Q

Name 5/6 specialised cells and what they’re specialised for

A

sperm cells - reproduction
nerve cells - rapid signalling
muscle cells - contraction
root hair cell - absorbing water + minerals
phloem + xylem cells - transporting substances

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18
Q

How is a sperm cell specialised?

A

lots of mitrochondria - provides energy from glucose
flagella + streamline head - mobility + movement
enzymes - digest through egg cell membrane
nucleus - contains DNA of father

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19
Q

How is a nerve cell specialised?

A

many endings - to connect with other adjacent nerve cells
myelin sheath - insulating cover
axon - (the extension of a nerve cell along which electrical impulses travel) to cover more distance

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20
Q

How is a muscle cell specialised?

A

lots of mitochondria - to generate energy for muscle contractions
(protein filaments - to determine shape and movement)

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21
Q

How is a root hair cell specialised?

A

Small thin extension - to increase surface area or root allowing plant to absorb more water + minerals from soil

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22
Q

How is a xylem cell specialised?

A

long cells and joined end to end - to form the xylem tube
hollow - so water can flow through

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23
Q

How is a phloem cell specialised?

A

long cells and joined end to end - to form the tube
few subcellular structure - so food substances (mainly sugars) can flow through

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24
Q

Where is genetic material found?

A

In the nucleus, in the form of a chromosome

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25
Q

Define chromosome

A

coiled up strands of DNA containing large numbers of genes

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26
Q

Define haploid cell/nucleus

A

A cell or nucleus of a gamete that has unpaired sets of chromosomes

they only have 23 single chromosomes not 23 pairs

27
Q

Define diploid cell/nucleus

A

A cell or nucleus that has a paired set of chromosomes

28
Q

Define gene

A

a section of a chromosome made from DNA that carries the code to make proteins

29
Q

Define allele

A

two versions of the same gene
one from mother, one from father

30
Q

How many chromosomes are there in a human cell?

A

46 - 23 pairs

31
Q

What do multicellular organisms use mitosis for?

A

to grow or replace cells that have been damaged

32
Q

What are the steps for mitosis?

A
  1. Chromosomes duplicate
  2. The chromosomes line up and the duplicates are then pulled apart to the opposite ends of the cell
  3. Two new nuclei form because membrane forms around the chromosomes
  4. The cytoplasm and cell membrane divide to form two cells
  5. Two identical daughter cells form with identical chromosomes
33
Q

What happens in stage 1 - before mitosis?

A
  • The chromosomes duplicate
  • Increase in amount of subcellular structures
  • cell growth
34
Q

What happens in stage 2 - during mitosis?

A
  • two nuclei form
  • chromosomes pulled to each end of cell
35
Q

What happens in stage 3 - after mitosis?

A
  • two identical cells form
  • cytoplasm / membrane divides
36
Q

Define stem cells

A

an undifferentiated cell that can develop into one or more types of specialised cell

37
Q

Where can stem cells be found in humans? What cells can they turn into?

A
  • in early human embryos (can turn into any cell in the body)
  • in bone marrow (can only turn into certain cells e.g. blood cells)
38
Q

How can bone marrow cure disease?

A

stem cells from a healthy person’s bone marrow can replace faulty blood cells in the patient

39
Q

How can embryonic stem cells cure disease? + example

A

embryonic stem cells can replace faulty cells
e.g. making insulin-producing cells for type 1 diabetic people
e.g. nerve cells for people paralysed by spinal injuries

40
Q

What is a pro of therapeutic cloning?

A

the cell wouldn’t be rejected by the patients body because the embryo would have the same genetic information as patient meaning stem cells produced contain the same genes

41
Q

What is are the risks of using stem cells?

A
  • stem cells grown in a lab may become contaminated with a virus which could be passed on
  • they could be rejected by the patient’s body (they would need to use immunosuppressant drug)
  • chance of tumor forming due to rapid divison
42
Q

Why are some people against stem cell research?

A

They believe that human embryos shouldn’t be experimented on because they’re a potential human life

43
Q

What are reasons for stem cell research?

A
  • curing existing patients who are suffering is more important than the rights of embryos
  • embryos are usually from fertility clinics and would’ve probably been destroyed anyway
44
Q

Define meristem

A

an area of a plant in which rapid cell division occurs - normally in the tip of the root or shoot

45
Q

Where are stem cells found in plants?

A

in the meristem

46
Q

What can stem cells, from plants, do?

A
  • produce clones of whole plants quickly and cheaply
  • grow crops of identical plants that have desired features (e.g. disease resistant)
  • differentiate into any type of plant for their whole life
  • used to grow more plants of rare species
47
Q

Define diffusion

A

the net movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached

48
Q

What increases the rate of diffusion?

A
  • high temperatures (because there is more energy)
  • bigger concentration gradients
49
Q

When a gas moves down the concentration gradient, does it move from high to low or low to high?

A

from high to low

50
Q

How do dissolved substances move in and out of cells?

A

through the cell membrane via diffusion

50
Q

Can starch and proteins diffuse through the cell membrane?

A

no, only small molecules

51
Q

What does a large surface area of the membrane increase?

A

increases the rate of diffusion

52
Q

Define osmosis

A

the net diffusion of water molecules from an area of higher water concentration to an area of lower water concentration across a partially permeable membrane

53
Q

Define partially permeable

A

allowing only substances of certain size through

54
Q

Do strong sugar solutions get more or less dilute during osmosis?

Is it up or down the concentration gradient?

A

more dilute because it has fewer water molecules

Down

55
Q

How do you observe the effect of sugar solutions on plant tissue?

osmosis practical

A
  1. Peel a potato and cut it into 3 identical cylinders (using a cork borer) or rectangles - each 3cm in length
  2. Place test tubes with the different sugar solutions: 0.5 mol/dm^3, 0.25 mol/dm^3, distilled water
  3. Weigh the mass of each potato and place into a test tube for 24 hrs
  4. Take them out and dry with a paper towel
  5. Measure mass and length
  6. The highest sugar solution should shrink the potato and the distilled water should have expanded the potato
56
Q

Define active transport

A

the movement of particles from an area of low concentration to an area of high concentration using energy

57
Q

Is active transport a passive process?

A

No, it requires energy.
Diffusion and osmosis are passive processes

58
Q

Where does the energy for active transport come from?

A

From respiration

59
Q

Where does active transport take place in a plant? Why?

A

The root hair cells - the concentration of minerals is usually higher in the plant than the soil

60
Q

Where does active transport take place in a human? Why?

A

In the small intestine/gut
When there is a lower concentration of nutrients in the gut than the blood.
Allowing glucose and amino acids to be transported to cells.

61
Q

How are your lungs/alevoli adapted for gas exchange?

A
  • large surface area
  • having moist membranes allowing substances to diffuse across them
  • having thin walls
  • having rich blood supply
  • breathing - providing a regular supply of fresh air
62
Q

How is your small intestine adapted for absorption of glucose?

A
  • they have villi which increase surface area
  • the villi have thin walls
  • they have a good blood supply
63
Q

How is a gill adapted for gas exchange?

A
  • has a large surface area due to gill filaments which are also covered in lamellae
  • lamallae have lots of blood capillaries
  • they have thin surface layer
  • blood flows in one direction whilst the water flows in the opposite - maintains a large concentration gradient

biology (4 decks)

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