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GCSE AQA Combined Science- Biology > Topic 1: Cell Biology > Flashcards

Topic 1: Cell Biology Flashcards

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1
Q

What microscope has the highest magnification?

A

Electron microscope

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2
Q

What microscope is used in schools?

A

Light microscope

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3
Q

What is the formula for magnification?

A

Magnification= image size/real size

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4
Q

What are studied using microscopes?

A

Cells

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5
Q

What are eukaryotes?

A

Organisms made up of eukaryotic cells

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6
Q

What are prokaryotes?

A

A prokaryotic cell

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7
Q

What is the function of the nucleus?

A

Contains genetic material of the cell

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8
Q

What is the function of the mitochondria?

A

Where aerobic respiration takes place

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9
Q

What is the function of the cytoplasm?

A

Where chemical reactions happen

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10
Q

What is the function of the cell membrane?

A

Controls what goes in and out of the cell

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11
Q

What is the function of the ribosomes?

A

Where proteins are made

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12
Q

What is the function of the cell wall?

A

Supports the cell/strengthens it

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13
Q

What is the function of the permanent vacuole?

A

Contains cell sap

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14
Q

What is the function of the chloroplasts?

A

Where photosynthesis occurs

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15
Q

What are bacteria?

A

Prokaryotes

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16
Q

What do bacteria cells not have?

A

A ‘true’ nucleus only a single circular strand of DNA in the cytoplasm, chloroplasts or mitochondria

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17
Q

What are the rings of DNA called?

A

Plasmids

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18
Q

What is the process of differentiation?

A

Differentiation is the process by which a cell changes to become specialised for it’s job

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19
Q

What is the function of a sperm cell?

A

To get male DNA to the female DNA

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20
Q

How are sperm cells specialised?

A
  • long tail to help swim to the egg
  • lots of mitochondria to provide energy needed
  • carries enzymes in head to digest through egg cell membrane
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21
Q

What is the function of nerve cells?

A

To carry electrical signals from one part of the body to another

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22
Q

How are nerve cells specialised?

A
  • long so can cover long distances

- branched connections to connect to other nerve cells and form a network around the body

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23
Q

What is the function of muscle cells?

A

To contract quickly

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24
Q

How are muscle cells specialised?

A
  • long so have space to contract

- lots of mitochondria to generate energy needed for contraction

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25
Q

What is the function of root hair cells?

A

Absorb water and minerals

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26
Q

How are root hair cells specialised?

A
  • long hairs that stick into soil which gives plant big surface area for absorbing water and mineral ions from soil
27
Q

What is the function of phloem and xylem cells?

A

xylem- transports water around the plant

phloem- transports food and minerals around plant

28
Q

How are phloem and xylem cells specialised?

A
  • cells joined end to end to make the tubes

- phloem cells have very few subcellular structures, so stuff can flow through them

29
Q

Where are stem cells found?

A

In early human embryos

30
Q

What can embryonic stem cells do?

A

Turn into ANY type of cell

31
Q

What could stem cells do?

A

May be able to cure many diseases

32
Q

Why are some people against stem cell research?

A

some people feel it’s potential human life

33
Q

How do stem cells produce identical plants?

A
  • stem cells found in meristems
  • cells in meristems can differentiate into any type of cell
  • stem cells can be used to produce clones
  • prevent a species being wiped out
  • grow crops for farmers
34
Q

What do chromosomes contain?

A

Genetic information

35
Q

Where are chromosomes found?

A

In the nucleus

36
Q

What do chromosomes do?

A

Carries large number of genes, different genes control different characteristics

37
Q

How many copies of chromosomes does everyone have?

A

Two copies, one from the mother and one from the father, we have 23 pairs of chromosomes

38
Q

What does the cell cycle do?

A

Makes cells for growth, development and repair

39
Q

What is mitosis?

A

The stage in the cell cycle when the cell divides

40
Q

What is the 2nd stage of the cell cycle?

A

Growth and DNA replication

41
Q

What happens at the end of the cell cycle?

A

Results in 2 new cells identical to the original cell, same number of chromosomes

42
Q

What is growth and DNA replication?

A
  • In a cell that’s not dividing, DNA splits out into long strings
  • Before it divides, the cell has to grow and increase the number of subcellular structures
  • DNA is duplicated and is copied into chromosomes, each ‘arm’ is a duplicate copy
43
Q

Describe mitosis

A
  • chromosomes line up and cell fibres pull them apart
  • membranes form around each set of chromosomes, these become nuclei of the two new cells- nucleus divided
  • cytoplasm and cell membrane divide
  • two new daughter cells are produced, exactly the same DNA and identical
44
Q

Define diffusion

A

the spreading out of particles from an area of high concentration to an area of low concentration

45
Q

What factors affect diffusion rate?

A
  • bigger concentration gradient: faster diffusion rate

- higher temperature: faster diffusion rate (particles have more energy)

46
Q

How do dissolved substances move in and out of cells?

A

by diffusion

47
Q

What can only diffuse through cell membranes?

A

Very small molecules such as oxygen, glucose, amino acids and water

48
Q

How does the surface area of the membrane affect diffusion rate?

A

The larger the surface area of the membrane, the faster the diffusion rate because more particles can pass through at once

49
Q

What is the definition of osmosis?

A

Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of a lower water concentration

50
Q

Why is osmosis a different type of diffusion?

A

movement of water particles from an area of higher water concentration to an area of lower water concentration

51
Q

How do root hairs take in minerals and water?

A
  • each branch of root covered in millions of microscopic hairs
  • gives plant large surface area for absorbing water + mineral ions from soil
52
Q

Why do plants need mineral ions?

A

For healthy growth

53
Q

Why can’t root hair cells use diffusion to take up minerals from the soil?

A

concentration of minerals usually higher in the root hair cells than in the soil around them

54
Q

How do root hair cells take up minerals?

A

Using active transport

55
Q

What is active transport?

A

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

56
Q

What does active transport allow?

A

allows the plant to absorb minerals from a very dilute solution, against a concentration gradient- essential for growth

57
Q

What does active transport need to work?

A

energy from respiration

58
Q

Why do humans need active transport?

A

it is used in the gut when lower concentration of nutrients in gut but higher concentration of nutrients in blood

59
Q

How does active transport in humans work?

A
  • when lower concentration of nutrients in gut compared to blood
  • means concentration gradient is wrong way
  • use active transport
  • allows nutrients to be taken in the blood despite fact concentration gradient is wrong way
60
Q

What are some examples of exchanging substances?

A
  • oxygen and carbon dioxide transferred between cells and the environment during gas exchange
  • in humans, urea diffuses from cells into blood plasma for removal of the body by the kidneys
61
Q

Why do organisms need to exchange substances?

A

to get rid of waste products

62
Q

Why do multicellular organisms need exchange surfaces?

A

they have smaller surface area compared to their volume- not enough substances can diffuse from their outside surface to supply their entire volume- need some sort of exchange surface for efficient diffusion

63
Q

How have exchange surfaces adapted to maximise effectiveness?

A
  • thin membrane: substances only have short distance to diffuse
  • large surface area : lots of substance can diffuse at once
  • lots of blood vessels: (animals) to get stuff into and out of the blood quickly
  • gas exchange surfaces: (animals) often ventilated- air moves in and out
64
Q

How does gas exchange happen in the lungs?

A
  • lungs transfer oxygen to the blood and remove CO2 from it
  • lungs contain millions of alveoli where gas exchange takes place
  • alveoli are specialised: an enormous surface area, good blood supply, very thin walls, moist lining for dissolving gases

GCSE AQA Combined Science- Biology (1 decks)

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