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AQA Biology GCSE > B1- Cell Structure > Flashcards

B1- Cell Structure Flashcards

1
Q

Equation Magnification

A

magnification = image size/ real object size

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2
Q

Definition Magnification

A

The number of times bigger the image is compared to the real object.

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3
Q

Definition Resolution

A

Smallest distance between two objects that can be distinguished.

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4
Q

What is order of magnitude?

A

A power to the base 10 used to quantify and compare size.

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5
Q

How does a light microscope work?

A

It passes a beam of light through a specimen, which travels through an eyepiece lens to be seen.

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6
Q

Advantages of light microscope (4)

A
  • Inexpensive
  • Easy to use
  • Portable
  • Lets you observe dead and living specimens
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7
Q

Disadvantage of light microscopes

A

Limited Resolution

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8
Q

How does an Electron microscope work?

A

Uses a beam of electrons which are focused using a magnet. The electrons hit a fluorescent screen which emits visible light, producing an image.

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9
Q

Two types of Electron Microscope

A
  • Transmission Electron Microscope
  • Scanning Electron Microscope
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10
Q

Advantages of Electron Microscope (2)

A
  • Greater Magnification
  • Higher Resolution
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11
Q

Why do Electron Microscopes have higher magnification and resolution?

A

Use a beam of electrons which have a shorter wavelength than photons of light.

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12
Q

How have Electron Microscopes enabled scientists to develop their understanding of cells? (2)

A
  • Allows small sub-cellular structures to be observed in detail.
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13
Q

Disadvantages of Electron Microscope (4)

A
  • Expensive
  • Large making it less portable
  • Requires training to use
  • Only dead specimens can be seen
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14
Q

How many metres in a cm?

A

1 x 10^-2

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15
Q

How many metres in a mm?

A

1 x 10^-3

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16
Q

How many metres in a micrometre?

A

1 x 10^-6

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17
Q

How many metres in a nanometre?

A

1 x 10^-9

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18
Q

Differences between Prokaryotic and Eukaryotic (3)

A
  • Prokaryotes are much smaller
  • Prokaryotes contain free DNA (no nucleus)
  • Prokaryotes may contain plasmids
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19
Q

What is the prokaryotic cell wall made of?

A

Peptidoglycan

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20
Q

What is the eukaryotic cell wall made of?

A

Cellulose (plants only)

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21
Q

How is genetic information stored in prokaryotic cells? (2)

A
  • Plasmid DNA
  • Chromosomal DNA (single loops)
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22
Q

Definition Plasmid

A

Small circular loops of DNA found free in the cytoplasm. That carry genes with genetic advances (antibiotic resistance)

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23
Q

List components of both plant and animal cell (5)

A
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • Nucleus
  • Cell membrane
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24
Q

List components only in plant cell not human (3)

A
  • Chloroplasts
  • Cell wall
  • Permanent Vacuole
25
Q

Function of the Nucleus

A
  • Controls cellular reactions and activities
  • Stores genetic information
26
Q

Structure of the Cytoplasm

A

Fluid (gel-like) component of the cell that contains organelles, enzymes and dissolved ions and nutrients.

27
Q

Function of the Cytoplasm

A

Site of cellular reactions. Mode of transport in the cell.

28
Q

Function of the Cell Membrane

A

Controls the materials that come in and out of the cell

29
Q

Function of the Mitochondria

A

Site of later stages of aerobic respiration in which ATP is produced.

30
Q

Function of the Ribosomes

A

Site of protein synthesis

31
Q

Function of plant Cell Wall

A

Strengthens the cell and prevents the cell from bursting when water enters via osmosis.

32
Q

What is inside of the permanent vacuole?

A

Cell Sap

33
Q

Function of Permanent Vacuole

A

Supports the cell and keeps it turgid

34
Q

Function of Chloroplasts

A

Site of photosynthesis

35
Q

Adaptations of Sperm cell (4)

A
  • Haploid nucleus (contains the genetic information)
  • Tail that enables movement
  • Mitochondria provides energy for tail movement
  • Acrosome contains enzymes that digest the eggs cell membrane to fertilise the egg.
36
Q

Adaptations of Nerve cells (3)

A
  • Lots of dendrites that make connections to other cells
  • Axons that carry the impulse from one place to another
  • Synapses are adapted to pass the impulse to another cell or between a nerve cell and a muscle cell
37
Q

Adaptations of Muscle cells (3)

A
  • Contain proteins that slide over each other and make the fibres contract
  • Contain many mitochondria to transfer energy needed for chemical reactions to take place
  • Store glycogen, which can be broken down and used in cellular respiration by the mitochondria to provide energy needed for the fibres to contract.
38
Q

Adaptations of Root Hair Cells (3)

A
  • Increased surface area for water to move into the cell
  • Permanent vacuole that speeds up movement of water by osmosis from the soil across the root hair cell
  • Many mitochondria to transfer energy needed for active transport
39
Q

Adaptations of Xylem Cells (2)

A
  • Alive at first but die and form long hollow tubes to allow water and mineral ions to move easily through them
  • Spirals is lignin make them very strong and help them to withstand pressure of water. Also help support phloem.
40
Q

Adaptations of Phloem Cells

A
  • Cell walls between the cells break down to form special sieve plates. Allow water carrying dissolved food to move freely
  • Supported by companion cells which transfer energy and support them.
41
Q

What is cell differentiation?

A

Process where cells become specialised

42
Q

Why is cell differentiation important?

A

Allows production of different tissues and organs that perform various vital functions in the human body.

43
Q

At what point in the the life cycle to cells differentiate in animal cells?

A

Early in their life cycle

44
Q

How long to plants retain the ability to differentiate?

A

Throughout their whole life cycle.

45
Q

What is the purpose of cell division in mature animals?

A

Repair and replacement of cells

46
Q

What changes does a cell go through when differentiating?

A

It becomes specialised by acquiring different sub-cellular structures to enable the cell to carry out a specialised function.

47
Q

How do bacteria multiply?

A

Binary Fission

48
Q

How often do bacteria multiply?

A

If all factors aren’t limited then once every 20 minutes

49
Q

Two ways bacteria can be grown

A
  • Nutrient broth solution
  • Colonies on an agar plate
50
Q

What nutrients make up a nutrient broth?

A

All nutrients required for bacterial growth i.e. Nitrogen- protein synthesis, Carbohydrates- energy and other minerals

51
Q

What are uncontaminated cultures of microorganisms needed for?

A

Investigating disinfectant and antibiotic action

52
Q

Describe Aseptic technique needed for preparing an uncontaminated culture (6)

A

1- Use pre-sterilised plastic Petri dishes or sterilise glass Petri dishes and agar gel before using an autoclave.
2- Pour the sterile agar gel into the Petri Dish and allow time to set.
3- Sterilise the inoculating loop by passing it through a Bunsen burner flame.
4- Dip the inoculating loop into the solution of microorganisms and make streaks using the loop along the surface of the agar.
5- Put the lid on the the Petri Dish and secure it with tape. Label it accordingly then turn and store upside.
6- Incubate the culture at 25 Degrees Celsius in the labs.

53
Q

Why must the Petri Dish be sterilised before use?

A

To kill any bacteria already present.

54
Q

How do you kill any bacteria on the inoculating loop? (2)

A
  • Pass it through the Bunsen burner flame
  • Dip it into acid (HCL)
55
Q

Why tape the lid down on the Petri dish?(2)

A
  • To Stop bacteria in the air contaminating the culture.
  • The lid isn’t fully sealed to avoid the growth of anaerobic bacteria in a lack of oxygen.
56
Q

Why do we store the Petri Dish upside down?

A

To prevent condensation from forming and dripping down into the colonies.

57
Q

Why incubate at 25 Degrees Celsius?

A

Harmful pathogens are less likely to grow at this temperature.

58
Q

What is the inhibition zone?

A

Uniformly circular zone of no bacteria growth in an area contaminated with bacterium.

59
Q

How to calculate effectiveness of antiseptic?

A

Area of circle = PI x r^2

AQA Biology GCSE (7 decks)

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