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Separate Biology Edexcel GCSE > Topic 1 - Key Concepts ( Cells And Microscopy ) > Flashcards

Topic 1 - Key Concepts ( Cells And Microscopy ) Flashcards

1
Q

State the two types of cell

A

Eukaryotic

Prokaryotic

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2
Q

What if the difference between a eukaryotic and prokaryotic cell?

A

A eukaryotic cell contains a nucleus and a membrane bound organelles. A prokaryotic cell does not

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3
Q

List the components of both plant and animal cells

A

Nucleus
Cytoplasm
Cell membrane
Mitochondria
Ribosomes

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4
Q

How is genetic information stored in a eukaryotic cell?

A

Within the nucleus, arranged in chromosomes

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5
Q

Other than storing genetic information, what is the function of the nucleus ?

A

Controls cellular activities

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6
Q

Describe the structure of the cytoplasm

A

Fluid component of the cell

Contains organelles, enzymes and dissolved ions and nutrients

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7
Q

What is the function of the cytoplasm?

A

Site of cellular reactions e.g first stage of respiration

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8
Q

What is the function of the cell membrane?

A

Controls the entry and exit of materials into and out of the cell

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9
Q

What is the function of the mitochondria ?

A

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

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10
Q

What is the function of the ribosomes ?

A

Joins amino acids in a specific order during translation

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11
Q

Which organelles are found in plant cells only?

A

Large permanent vacuole
Cell wall
Chloroplasts

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12
Q

What is the cell wall made of ?

A

Cellulose

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13
Q

What is the function of the cell wall?

A

Provides strength
Prevents the cell bursting when water enters by osmosis

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14
Q

What does permanent vacuole contain?

A

A solution of salts , sugars and organic acids

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15
Q

What is the function of the permanent vacuole ?

A

Supports the cell, maintaining its turgidity

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16
Q

What is the function of the chloroplasts ?

A

Site of photosyntheses

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17
Q

When looking at a cell using a light microscope, why do chloroplasts appear green?

A

Contain chlorophyll , a green pigment

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18
Q

List the organelles found in prokaryotic cells

A

Chromosomal DNA
Plasmid DNA
Cell wall
Cell membrane
Ribosomes
Flagella

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19
Q

How is genetic information stored in a prokaryotic cell?

A

Found free within the cytoplasm as :

  • chromosomal DNA
  • plasmid DNA
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20
Q

What are plasmids?

A
  • small circular loops of DNA found free in the cytoplasm and separate from the main DNA
  • carry genes that provide genetic advantages - antibiotic resistance
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21
Q

What is the prokaryotic cell wall made of?

A

Peptidoglycan

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22
Q

What is a flagellum ?

A
  • long rotating whip like protrusion
    Enables bacteria to move
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23
Q

What is a haploid cell ?

A

A cell that contains a single copy of each chromosome ( half the number of chromosomes )
23 in humans

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24
Q

What is a diploid cell ?

A

A cell that contains two copies of each chromosome ( full set of chromosomes)
46 in humans

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25
Q

What are gametes ?

A

Reproductive cell ( egg and sperm )
Haploid

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26
Q

Describe sexual reproduction in terms of chromosome number

A

Two haploid gametes fuse
Resulting embryo has 2 chromosomes for each gene and 2 copies of each allele

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27
Q

Egg cell adaptations

A
  • haploid nucleus
  • mitochondria in cytoplasm - energy for developing embryo
  • cytoplasm- nutrients for developing embryo
  • cell membrane hardens after fertilisation, preventing the entry of other sperm and ensuring the zygote is diploid
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28
Q

Sperm cell adaptations

A
  • haploid nucleus carries genetic information
  • tail for movement
  • mitochondria provide energy for tail movement
  • acrosome enzymes that digest egg cell membrane
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29
Q

Where are ciliates epithelial cells found?

A

Found lining the surface of structures such as the respiratory tract and uterus

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30
Q

Function of ciliated epithelial cells lining the airways

A

Move in synchronised waves to beat mucus up to the back of the throat where it can be swallowed

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31
Q

What is magnification?

A

The number of times bigger an image appears compared to the size of the specimen

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32
Q

How can to total magnification of an image be calculated from lens powers ?

A

Eyepiece lens magnification x objective lens magnification

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33
Q

How can magnification of image be calculated?

A

Size of image / size of specimen

34
Q

What is resolution ?

A

The smallest distance between two objects that can be distinguished

35
Q

How does a light microscope work ?

A

Passes a beam of light through a specimen which travels through the eyepiece lens , allowing the specimen to be seen

36
Q

Advantages of a light microscope

A
  • inexpensive
  • easy to use
  • portable
  • observe both living and dead species
37
Q

What is the disadvantage of light microscope

A

Limited resolution

38
Q

How does an electron microscope work ?

A

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

39
Q

What is the advantage of electron microscopes?

A

Greater magnification and resolution

40
Q

Why do electron microscopes have a greater magnification and resolution ?

A

They use a beam of electrons which has a shorter wavelength than photons of light

41
Q

How have electron microscopes enabled scientists to develop their understanding of cells?

A
  • allow small sub-cellular structures to be observed in detail
  • enable scientists to develop more accurate e plan out how cell structures relate to their function
42
Q

Disadvantages of an electron microscope?

A
  • Expensive
  • large so less portable
  • require training to use
  • only dead specimens can be observed
43
Q

How do you covert from m to mm

A

X 1000

44
Q

How do you convert from m to micrometres?

A

X 10^6

45
Q

How do you convert from m to nm ?

A

X 10^9

46
Q

How do you convert from nm to m?

A

X 10^-9

47
Q

How do you convert from m to pm?

A

X10^12

48
Q

What are enzymes?

A

Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves

49
Q

What is an advantage of enzymes in the body?

A

The enable cellular reactions to take place at lower temperatures

50
Q

What is the active site of an enzymes?

A

The region of an enzyme to which a substrate molecule binds and the reaction takes place

51
Q

Why are enzymes described as having a high specificity for their substrate?

A

Only substrates with a specific complementary shape can fit into an enzyme’s active site

52
Q

Describe lock and key model

A
  • substrate binds with the active site of an enzyme
  • substrate binds, enzyme substrate complex forms
  • substrate converted to products
  • products released from the active site which is now free to bind to another substrate
53
Q

What factors affect the rate of an enzyme controlled reaction?

A
  • temp
  • pH
  • substrate concentration
54
Q

How does increasing temp initially affect the rate of an enzyme controlled reaction?

A
  • as temp increases molecules have more KE
  • movement of molecules increases
  • probability of a successful illusion increases
  • more enzyme substrate complexes from
  • rate of reaction increases
55
Q

How does increasing temp above the optimum affect the rate of an enzyme controlled reaction

A

-increased vibrations break bonds in enzyme’s structure
- active site changes shale, enzymes structure
- active site changes shape , enzyme is denatured

  • no more enzyme substrate complexes can form
  • rate of reaction decreases
56
Q

How does pH affect the rate of an enzyme controlled reaction?

A
  • enzyme shave an optimum pH
  • pH shifts from the optimum
  • bonds in the enzyme’s structure are altered
  • active site changes shape
    Enzyme is denatures
  • rate of reaction decreases
57
Q

Explain how the substrate concentration affects the rate of an enzyme controlled reaction

A
  • substrate concentration increases
  • number of substrate molecules in the same volume increases
  • probability of a successful collision increases
  • more enzyme substrate complexes form
  • rate of reaction increases
  • once all active sites become full, the rate of reaction plateaus
58
Q

How can rate of an enzyme controlled reaction be calculated when given a value for time?

A

Rate = 1/ time

59
Q

What are the units for rate?

A

S^-1

60
Q

Why must large organic molecules be broken down into smaller, simpler molecules in the body?

A
  • large molecules are too big to be absorbed across the surface of the gut wall
  • large molecules are broken down into smaller molecules for absorbtion into the bloodstream
61
Q

Give an example of the breakdown of large molecules into smaller molecules in plants

A

Starch is broken down by enzymes into simp,e sugars which are repaired to release energy

62
Q

What type of molecules are proteins and carbohydrates?

A

Polymers

63
Q

What are the monomers of carbohydrates?

A

Simple sugars

64
Q

Which group of enzymes catalyses the breakdown of carbohydrates?

A

Carbohydrases

65
Q

Which type of carbohydrase catalyses the breakdown of starch?

A

Amylase

66
Q

What are the monomers of proteins ?

A

Amino acids

67
Q

Which type of enzymes catalyses the breakdown of proteins ?

A

Proteases

68
Q

What is the function of lipases?

A

Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol

69
Q

Why are small organic molecules synthesised into larger organic molecules in the body?

A

Large molecules are used for stargaze (glycogen) or are used to build structures ( organelles)

70
Q

Which enzyme catalyses the formation of glycogen from glucose?

A

Glycogen synthase

71
Q

How can the amount of energy in food be measured?

A

Calorimetry

72
Q

What is calorimetry ?

A

A method of measuring the heat transfer during a chemical reaction

73
Q

Describe the method used to measure the amount of energy in a sample of food

A
  1. Add a set volume of water to a boiling tube and record initial temperature
  2. Record the mass of a small sample of food
    £. Stick the sample onto a mounted needle
  3. Using a Bunsen burner light the food sample
  4. Hold the sample under the boiling tube until it burns up
  5. Record the maximum temperature reached by the water
  6. Record the final mass of the food sample
74
Q

How can the amount of energy in the food sample be calculated?

A

Energy in food = mass of water(g) x temp change of water x 4.2

Energy = energy in food/ mass of food burnt

75
Q

What is simple diffusion?

A
  • the net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
76
Q

What molecules enter and leave cells via simple diffusion through the cell membrane?

A

Small molecules e.g oxygen, water, glucose, amino acids

77
Q

What factors affect the rate of diffusion

A
  • temperature
  • concentration gradient
  • surface area of cell membrane
78
Q

Define osmosis

A

The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane

79
Q

What is active transport?

A

The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration, against the concentration gradient using energy

80
Q

How is a percentage change in mass calculated?

A

% change = final mass - initial mass / initial mass x 100

Separate Biology Edexcel GCSE (5 decks)

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