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AQA GCSE Biology > Cell biology > Flashcards

Cell biology Flashcards

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1
Q

Features of an animal cell

A

Cell membrane- to control what enters and exists the cell
Nucleus- to control cell activity
Cytoplasm- the site of most chemical reactions
Ribosomes- the site of protein synthesis
mitochondria- the site of respiration

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2
Q

Features of a plant cell

A

{same as animal cells}
Cell wall- a cellulose structure that supports and strengthens the cell
Vacuole- contains cell sap, a weak sugar and salt solution
Chloroplast- the site of photosynthesis

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3
Q

Eukaryotic Cells

A

A type of cell which has a cell membrane and genetic information enclosed within the nucleus
(e.g. plant and animal cells)

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4
Q

Prokaryotic Cells

A

A type of cell that is much smaller then a Eukaryotic and have a cytoplasm, cell membrane and cell wall
the genetic information is enclosed within a DNA loop and plasmid rings
(e.g. bacterial cells)

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5
Q

Sperm cell: function & adaptions

A

Function: to swim to the egg cells
- long tail and streamlined head to help it swim
-large amount of mitochondria at the tip to provide more energy
-enzymes in it’s head to digest the egg cell membrane

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6
Q

Nerve cell: function & adaptions

A

Function: to carry electrical signals through the body
-long to be able to cover a larger distance
- branched connections at the end of them to connect to other cells

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7
Q

Muscle cell: function & adaptions

A

Function: to contract repeatedly and quickly
-large amount of mitochondria to be able to release more energy
-cells are long to have more space to contract

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8
Q

Root hair cell: function & adaption

A

Function: to absorb water and minerals from the surface of plant roots
-long hairs stick out from the cell to increase surface area to absorb plants and minerals

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9
Q

Xylem cells: function & adaption

A

Function: to carry water and minerals ions upwards through the plant
- strengthened by lignin
- hollow in the centre to allow dissolved substances to flow

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10
Q

Phloem cells: function and adaption

A

Function: transport food substances around the plant (in two directions)
-small pores in the ends of elongated living cells allow for cell sap to flow

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11
Q

Specialised cell

A

Cells that have specific features adapted to carry out it’s function

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12
Q

Cell Differentiation

A

The process of a cell changing to become specialised for it’s function: often including a cell changing its sub-cellular structures to enable it to carry out it’s function. It becomes a specialised cell

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13
Q

Binary fission

A

A type of cell division that occurs in prokaryotic. cells (bacteria) which involves the cell making copies of it’s DNA before splitting into two daughter cells
(Bacterial cells can multiply every 20mins if they have the suitable nutrients and temp)

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14
Q

The process of Binary fission

A

-The DNA ring and plasmid replicate
-As the cell gets larger the DNA strands move to opposite ends of the cell
-Cytoplasm begins to divide and new cell walls begin to form
-Two daughter cells are produced, each with one copy of the DNA strand but a variable no. of plasmid rings

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15
Q

Antibiotic

A

medicine that destroys microorganisms or inhibits their growth

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16
Q

Disinfect

A

A chemical liquid that destroys bacteria (applied to none living surfaces)

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17
Q

Antiseptic

A

a microbial substance applied to tissue or skin

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18
Q

Microbiology RP

A
  • Culture the microbe by pouring hot agar into a shallow round plastic dish (petri dish)
  • Once cooled heat an inoculating loop and transfer the paper disc (that’s been dipped in antiseptic) into the bacterial culture
  • immediatly put the lid onto the Petri dish and seal with two pieces of tape before incubating the culture at 25’ to promote microbial growth
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19
Q

Calculating the zone of inhibition

A

π r2

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20
Q

Chromosomes

A

Coiled up molecules of DNA found in the nucleus that carry many genes

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21
Q

Mitosis

A

A type of cell division in where a cell reproduces to form two identical offspring

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22
Q

Why do cells divide?

A
  • growth
  • to replace worn out cells
  • to repair damaged tissue
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23
Q

The cell cycle

A

The series of stages in which a cell multiplies to produce two genetically identical daughter cells

24
Q

The stages of the cell cycle

A
  1. Growth and DNA replication
  2. Mitosis (cell division)
  3. Mitosis ends and the cells rest
25
Q

The process of Mitosis

A

-The cell starts off as a normal (parent) cell

1- The DNA replicates to form two copies of each chromosome
1- Simultaneously the other organelle in the cell duplicate
2- One set of chromosomes is pulled to each end of the cell as the spindle fibres pull them apart
2- membranes form around each set of chromosomes (these are the new nuclei)
2- Finally the cytoplasm and cell membrane divide to produce two genetically identical daughter cells
3- Cell division stops, and the genetically identical daughter cells rest

26
Q

Stem cells

A

An undifferentiated cell that can become one of many different types of cells or produce more stem cells
- Embryos (that can turn into ANY type of cell)
- Adult bone marrow (where they can turn into SOME types of cells)
- Meristems (can turn into ANY type of cell)

27
Q

Using Stem cells to cure diseases

A
  • Embryonic cells could be used to replace faulty cells within sick people (e.g. insulin for diabetes)
  • When replacing faulty cells, therapeutic cloning can create an embryo with the same genetic information as the patient so the patients body is less likely to reject the new cells
28
Q

Stem Cells in plants

A
  • Produce clones of plants quickly and cheaply
  • Grow more rare species of plants (to prevent extinction
  • Grow identical plants with a desirable quality (e.g. disease resistant)
29
Q

Pro’s of Stem Cells

A
  • Curing diseases
  • Prevent extinction
  • Produce disease resistant crops
30
Q

Con’s of Stem Cells

A
  • Expensive
  • Religious reasons
  • Could be killing potential life
31
Q

Resolution

A

The ability to distinguish between two points
(a higher resolution would give a sharper image)

32
Q

Electron Microscopes

A

Use electrons which pass through the object to generate an image

33
Q

Pro’s of Electron microscopes

A
  • Higher magnification
  • They have a higher resolution (so a sharper image)
  • Allow us to see the insides of some sub cellular structures (mitochondria and chloroplasts)
  • Allow us to see smaller sub cellular structures (ribosomes and plasmids)
34
Q

Con’s of Electron microscopes

A
  • The specimen must be dead to allow electrons to pass through and produce an image
  • relatively expensive
  • large
35
Q

Light microscopes

A

Use light and lenses to form an image of a specimen and then magnify it
They allow us to see cells and large sub cellular structures (like nuclei)

36
Q

Pro’s of Light microscopes

A
  • Relatively cheaper
  • smaller then light microscopes
37
Q

Con’s of light microscopes

A
  • Lower magnification
  • Lower resolution
  • Smaller
38
Q

Calculating magnification

A

I = A*M

I= image size
A= actual size
M= magnification

39
Q

A slide

A

A strip of clear glass/plastic onto which a specimen is mounted

40
Q

Using a stain

A

A stain is used to highlight objects within a cell by adding colour to them (often iodine)

41
Q

Preparing a slide

A
  • Add a drop of water to the centre of a clean slide
  • Separate the layers of an onion and use tweezers to pull now epidermal tissue from the bottom of one of the layers
  • Place the tissue into the water on the slide
  • Add a drop of iodine solution (as a stain)
  • Place a cover slip (square shaped glass/plastic) onto by carefully tilting the slip from an upright position onto the specimen without getting any air bubbles
42
Q

Drawing observations

A
  • Use a pencil WITH a sharp point
  • Clear, Unbroken lines
  • Must take up at least half of the space provided
  • NO colouring OR shading
  • Sub cellular structures must be drawn in proportion
  • Include a tittle AND the magnification
  • Label the important features WITH straight uncrossed lines
43
Q

concentration gradient

A

the difference in concentration between two areas

44
Q

diffusion

A

the movement of a substance from a higher concentration to a region of lower concentration
(occurs in liquids and gases)

45
Q

Factors affecting diffusion

A
  • concentration gradient
  • heat
  • surface area
46
Q

Osmosis

A

the movement of water molecules from a region go higher concentration to a region of lower concentration across a semi permeable membrane
(osmosis will continue to take place till the concentration is equal on both sides of the membrane)

47
Q

Partially permeable membrane

A

a membrane with tiny holes to allow tiny molecules (like water) to pass through but not larger ones (like sucrose)

48
Q

Osmosis RP

A
  • Full 2 cylinders, one with pure water and one with 1mol of sugar solution)
  • cut and weigh two cylinders of potato (record the mass)
  • remove the potato from the solution and dry if before weighing it again
  • use the mass to calculate the percentage change in mass
  • (the percentage change should be higher in the lower concentrated solution as more water can enter the cell)
49
Q

Calculating percentage change in mass

A

(change in mass/start mass) *100

50
Q

Osmosis RP, causes for error

A
  • potato may not be fully dried
  • water may have evaporated from the beaker (concentration changes)
    (repeat the study and calculate the mean)
51
Q

Active transport

A

substances moving from a lower concentration to an area of higher concentration using metabolic energy AGAINST the concentration gradient

52
Q

Why active transports needed

A

to allow mineral ions and sugar molecules to be absorbed from the soil into plants to allow healthy growth in the plant (and respiration)

53
Q

Lungs & alveoli adaptions

A
  • Large surface area
  • thin walls
  • good blood supply
54
Q

Small intestine/villi adaptions

A
  • thin walls
  • good blood supply
  • large surface area
55
Q

Fish gills adaptions

A

Oxygen in the water is diffused into the gills which are made up of gill filaments which are covered in tiny structures (lamellae)
- thin membrane
- large concentration gradient
-large surface area

56
Q

Plant leaf adaptions

A
  • flat shape increases surface area
  • guard cells control the size of the stomata
57
Q

Stomata

A

A hole in the surface of the leaf which allows gas exchange to take place

AQA GCSE Biology (1 decks)

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