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Biology > SB1: Key concepts > Flashcards

SB1: Key concepts Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

State the two types of cells.

A

Eukaryotic and Prokaryotic

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2
Q

What is the difference between a prokaryotic and eukaryotic cells?

A

A eukaryotic cell contains a nucleus and membrane-bound organelles. A prokaryotic cell doesn’t.

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3
Q

List the components of both plant and animal cells [5 marks]

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.

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5
Q

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

A

Controls cell’s activities.

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6
Q

Describe the structure of the cytoplasm.

A

Jelly-like substance which contain organelles, enzymes and dissolved nutrients

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7
Q

What is the function of the cytoplasm?

A

The site of all cellular reactions.

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8
Q

What is the function of the cell membrane?

A

Controls what enters and exits the cell

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9
Q

What is the function of the mitochondria?

A

The site of aerobic respiration.

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10
Q

What is the function of ribosomes?

A

Produces proteins through protein synthesis.

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11
Q

Which organelles are found in plant cells only? [3 marks]

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

Strengthens cell.

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14
Q

What does the permanent vacuole contain?

A

A solution of salts and sugars.

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15
Q

What is the function of the permanent vacuole?

A

Supports the cell, maintaining its structure.

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16
Q

What is the function of chloroplasts?

A

The site of photosynthesis.

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17
Q

Why do chloroplasts appear green?

A

They contain chlorophyll, a green pigment.

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18
Q

List the organelles found in prokaryotic cells. [6 marks]

A

Chromosomal DNA
Plasmid DNA
Cell wall (Jelly Coat)
Cell membrane
Ribosomes
Flagellum

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19
Q

How is the genetic information stored in a prokaryotic cell?

A

They are found floating freely within the cytoplasm. 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. They carry genes that provide genetic advantages (e.g. 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 haploid cell?

A

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

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23
Q

What is a diploid cell?

A

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

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24
Q

What are gametes?

A

Reproductive cells (egg and sperm cells). They are haploid cells.

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25
Q

Describe sexual reprouction in terms of chromosome number. [2 marks]

A

Two haploid gametes fuse together this results in the formation of an embryo which now has two chromosomes for each gene and two copies of each allele (one from the father/sperm and one from the mother/ egg)

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26
Q

Describe how egg cells are adapted to their function. [4 marks]

A

Haploid nucleus contains genetic information. Mitochondria in cytoplasm produce energy for the developing embryo. Cytoplasm contains nutrients for the developing nutrients. Cell membrane hardens after fertilisation, preventing the entry of other sperm and ensuring the zygote (embryo) is diploid.

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27
Q

Describe how sperm cells are adapted to their function?

A

Haploid nucleus contains genetic information. The tail enables movement. Mitochondria provides energy for tail movement. Acrosome contains enzymes that digest the egg cell membrane so the sperm can enter the egg cell and fuse with it.

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28
Q

Where are ciliated epithelial cells found?

A

Found in the respiratory tract and uterus

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29
Q

Describe the function of ciliated epithelial cells lining in the airways.

A

They move mucus (which contain dirt and pathogens) out of the airways.

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30
Q

What is magnification?

A

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

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31
Q

How can total magnification be calculated from lens power?

A

total magnification = eyepiece lens x objective lens magnification

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32
Q

How can the magnification of an image be calculated?

A

magnification = Image size / Actual size of specimen

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33
Q

What is resolution?

A

The smallest distance between two objects that can be distinguished.

34
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 observed.

35
Q

What are the advantages of light microscopes? [4 marks]

A

Cheap. Easy to use.
Easy to carry around.
Can observe dead and living specimens.

36
Q

What is the disadvantage of light microscopes?

A

Limited resolution.

37
Q

How does an electron microscope work?

A

It uses a beam of electrons which are shot at the specimen. The electrons hit a fluorescent screen which emits visible light, producing an image.

38
Q

Name the two types of electron microscopes?

A

Transmission electron microscope (TEM) & Scanning electron microscope (SEM)

39
Q

What is the advantage of electron microscope?

A

Greater magnification and resolution.

40
Q

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

A

Allowed small sub-cellular structures to be observed in detail. Enabled scientists to develop more accurate explanations about how cell structure relates to function.

41
Q

What are the disadvantages of electron microscopes? [4 marks]

A

Expensive. Not easy to carry around. Requires training to use. ONLY dead specimens can be used/observed.

42
Q

How do you convert m to mm?

A

x1000

43
Q

How do you convert m to μm?

A

x 1,000,000

44
Q

How do you convert m to nm?

A

x 1,000,000,000

45
Q

How do you convert nm to m?

A

÷ 1,000,000,000

46
Q

How do you convert form m to pm (picometre)?

A

x 1,000,000,000,000

47
Q

Write 0.005 in standard form.

A

5 x 10^-3

48
Q

Write 10300 in standard form.

A

1.03 x 10^4

49
Q

What are enzymes?

A

Biological catalysts that increase the rate of chemical reactions.

50
Q

What is an advantage of enzymes in the body?

A

They enable cell reactions to take place at lower temperatures.

51
Q

What is the active site of an enzyme?

A

The region where the substrate binds to the enzyme.

52
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.

53
Q

Describe the ‘lock and key’ theory. [4 marks]

A

Substrate collides with the active site of an enzyme. Substrate binds, enzyme-substrate complex forms. Substrates are converted to products. Products made by the active site which is now free to bind to another substrate

54
Q

Which factors affect the rate of an enzyme’s reaction?

A

Temperature, pH & Substrate concentration.

55
Q

Explain how increasing temperature initially affects the rate of an enzyme controlled reaction.

A

As temperature increases molecules have more kinetic energy. So the movement of molecules increases. Therefore the probability of a successful collision increases. More enzyme-substrate complexes form. As a result rate of reaction increases.

56
Q

Explain how increasing temperature above the optimum affects the rate of an enzyme controlled reaction.

A

Temperature increases above the optimum. Increased vibrations break bonds in the enzyme’s structure. Active site of the enzyme denatures. So no more enzyme-substrate complexes form. As a result the rate of reaction decreases.

57
Q

Explain how pH affects the rate of an enzyme controlled reaction.

A

Enzymes have an optimum pH. pH shifts from the optimum. Bonds in the enzyme’s structure are altered. Active site changes shape, enzyme is denatured. As a result the rate of reaction decreases.

58
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. So more enzyme-substrate complexes form. As a result the rate of reaction increases but once all the active sites become full, the rate of reaction plateaus.

59
Q

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

A

rate = 1/time

60
Q

What are the units for rate?

A

s^-1

61
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 intestines. Therefore large molecules are broken down into smaller molecules for absorption into the bloodstream.

62
Q

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

A

Starch is broken down by enzymes into simpler sugars which are respired to release energy.

63
Q

What type of molecules are protein and carbohydrates?

A

Polymers.

64
Q

What are the monomers of carbohydrates?

A

Simple sugars.

65
Q

Which group of enzymes catalyses the breakdown of carbohydrates?

A

Carbohydrases.

66
Q

Which type of enzyme catalyses the breakdown of starch?

A

Amylase.

67
Q

What are the monomers of proteins?

A

Amino acids.

68
Q

Which type of enzyme catalyses the breakdown of proteins?

A

Proteases.

69
Q

What is the function of lipases?

A

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

70
Q

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

A

Large molecules are used for storage or are used to build structures (e.g. organelles)

71
Q

Which enzyme catalyses the formation of glycogen from glucose?

A

Glycogen synthase.

72
Q

How can amount of energy contained in food be measured?

A

Measured using a calorimeter.

73
Q

What is a calorimeter?

A

A method of measuring the heat transfer during a chemical reaction.

74
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, record initial temperature.
  2. Record the mass of a sample of food.
  3. Stick the sample onto a mounted needle.
  4. Using a bunsen burner light the food sample.
  5. Hold the sample under the boiling tube until it burns up.
  6. Record the maximum temperature reached by the water.
  7. Record the final mass of the food sample.
75
Q

How can energy in the food sample be calculated?

A

Energy in food (J) = Mass of Water (g) x Temperature change of water (°C) x 4.2
OR
Energy (J/g) = Energy in food (J) / Mass of food burnt (g)

76
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.

77
Q

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

A

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

78
Q

What factors affect the rate of diffusion? [3 marks]

A

Temperature, Concentration gradient & Surface area of cell membrane

79
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.

80
Q

What is active transport?

A

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

81
Q

How is percentage change in mass calculated?

A

% change = (final mass - intial mass/ initial mass) x 100

Biology (3 decks)

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