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Topic 1 - Key concepts Flashcards

1
Q

What are enzymes?

A

Biological catalysts

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2
Q

What is an advantage of enzymes in the body?

A

They enable cellular reactions to take place at lower temperatures

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3
Q

What is the active site of an enzyme?

A

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

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4
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

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5
Q

Describe the lock and key model

A
  1. Substrate collides with the active site of an enzyme
  2. Substrate binds, enzyme substrate complex forms
  3. Substrate converted to products
  4. Products released from the active site which is now free to bind to another substrate
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6
Q

What factors affect the rate of an enzyme-controlled reaction?

A

Temperature
pH
Substrate concentration

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7
Q

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

A

As temperature umolecules have more KE so their movement increases
The probability of a successful collision increases
More enzyme-substrate complexes form
The rate of reaction increases

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8
Q

How does increasing temperature above the optimism affect the rate of an enzyme-controlled reaction?

A

The increased vibrations break bonds in the enzyme’s structure
The active site changes shape so the enzyme is denatured
No more enzyme-substrate complexes can form
The rate of reaction decreases

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9
Q

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

A

They have an optimum pH when it moves from that the bonds in the enzyme’s structure are altered so the enzyme is denatured and the rate of reaction decreases

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10
Q

How does substrate concentration affect 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 the active sites become full, the rate of reaction plateaus

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11
Q

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

A

Rate = 1/time

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12
Q

What are the units for rate?

A

S^-1

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13
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
They are broken down into smaller molecules for absorption into the bloodstream

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14
Q

What type of molecules are proteins and carbohydrates?

A

Polymers

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15
Q

What are the monomers of carbohydrates?

A

Simple sugars

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16
Q

Which group of enzymes catalysed the breakdown of carbohydrates?

A

Carbohydrates

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17
Q

Which type of carbohydrase catalyses the breakdown of starch?

A

Amylase

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18
Q

What are the monomers of proteins?

A

Amino acids

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19
Q

Which type of enzyme catalysts the breakdown of proteins?

A

Proteases

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20
Q

What is the function of lipases?

A

Enzymes whichCatalyse the breakdown of lipids into fatty acids and glycerol

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21
Q

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

A

Large molecules are used for storage or to build structures

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22
Q

Which enzyme catalysts the formation of glycogen from glucose?

A

Glycogen synthase

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23
Q

How can the amount of energy contained in food be measured?

A

Using calorimetry

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24
Q

What is calorimetry?

A

A method of measuring the heat transform during a chemical reaction

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25
Describe the method used to measure the amount of energy in a sample of food
1. Add a set volume of water to a boiling tube, record initial temperature 2. Record mass of a small sample of food 3. Stick the sample onto 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
26
How can’t he amount of energy in the food sample be calculated?
Energy in food = mass of water x temperature change of water x 4.2
27
State the two types of cell
Eukaryotic and prokaryotic
28
What is the difference between a eukaryotic and prokaryotic cell?
A eukaryotic contains a nuclear study and membrane-bound organelles. A prokaryotic cell does not
29
List the components of both plant and animal cells
``` Nucleus Cytoplasm Cell membrane Mitochondria Ribosomes ```
30
How is genetic information stored in a eukaryotic cell?
Within the nucleus, arranged in chromosomes
31
Other than storing genetic information, what is the function of the nucleus?
To control cellular activities
32
Describe the structure of the cytoplasm
Fluid component of the cell | Contains organelles, enzymes and dissolved ions and nutrients
33
What is the function of the cytoplasm?
It is the site of cellular reactions
34
What is the function of the cell membrane?
Controls the entry and exit of materials into and out of the cell
35
What is the function of the mitochondria?
This site of later stages of aerobic respiration in which ATP is produced
36
What is the function of ribosomes?
Joins amino acids in a specific order during translation
37
Which organelles are found in plant cells only?
Large, permanent vacuole Cell wall Chloroplasts
38
What is the cell wall made of?
Cellulose
39
What is the function of the cell wall?
Provides strength | Prevents the cell bursting when water enters by osmosis
40
What does the permanent vacuole contain?
A solution of salts, sugars and organic acids
41
What is the function of the permanent vacuole?
Supports the cell, maintaining this turgidity
42
What is the function of the chloroplasts?
They ar the site of photosynthesis
43
When looking at a cell sousing a light microscope, why do chloroplasts appear green?
They contain chlorophyll
44
List the organelles found in prokaryotic cells
``` Chromosomal DNA Plasmid DNA Cell wall Cell membrane Ribosomes Flagella ```
45
How is genetic information stored in a prokaryotic cell?
Free in the cytoplasm as chromosomal DNA and plasmid DNA
46
What are plasmids?
Small circular loops of DNA found free in the cytoplasm and separate from the main DNA that carry genes that provide genetic advantages
47
What is the prokaryotic cell wall composed of?
Poptidoglycan
48
What is a flagellum?
A long, rotating, whip like profusion that enables bacteria to move
49
What is a haploid cell?
A cell that contains a single copy of each chromosome (half)
50
What is a diploid cell?
A cell that contains two copies of each chromosome (full set)
51
What are gametes?
Repreductive cells | They are haploid
52
Describe the sexual reproduction in terms of chromosome number
Two haploid gametes fuse | Results in and embryo which has two chromosomes for each gene
53
Describe how egg cells are adapted to their function
Haploid nucleus contains genetic material Mitochondria in cytoplasm produce energy for the developing embryo Cytoplasm contains nutrients for the developing embryo Cell membrane hardens after fertilisation, preventing the entry of other sperm and ensuring the zygote is diploid
54
Describe how sperm cells are adapted to their function
Haploid nucleus contains genetic information Tail enables movement Mitochondria provide energy for tail movement Acrosome contains enzymes that digest the egg cell membrane
55
Where are ciliates epithelial cells found?
Lining the surface of structures such as the uterus and respiratory tract
56
Describe the function of ciliates epithelial cells lining the airways
They move in synchronised waves to beat mucus up to the back of the throat where is can be swallowed
57
What is magnification?
The number of times bigger an imag appears compared to the size of the specimen
58
How can the total magnification of an image be calculated from lens powers?
Total magnification = eyepiece lens magnification x objective lens magnification
59
How can the magnification of an image be calculated?
Magnification = size of image / size of specimen
60
What is resolution?
The smallest distance between two objects that can be distinguished
61
How does a light microscope work?
Passes a beam of light through a specimen which travels through the eyepiece lens, allowing the specimen to be observed
62
What are the advantages of light microscope?
Inexpensive Easy to use Portable Observe both dead and living specimens
63
What is the disadvantage of light microscopes?
Limited resolution
64
How does an electron microscope work?
It uses a beam of electrons which are focused using magnets. The electrons hit a fluorescent screen which emits visible light, producing an image
65
Name the two types of electron microscope
Transmission electron microscope | Scanning electron microscope
66
What is the advantage of electron microscopes?
Treated magnification and resolution
67
Why do electron microscopes have a greater magnification and resolution?
They use a beam of electrons which has a shorter wavelength than photons of light
68
How have electron microscopes enabled scientists to develop their understand of cells?
Allow small sub-cellular structures to be observed in detail | Enable scientists to develop more accurate explanations about how cell structure relates to function
69
What are the disadvantages of electron microscopes?
Expensive Large so less portable Require training to use Only dead specimens can be observed
70
How do you convert m to me?
X 1000
71
How do you convert from m to um?
X 1000000
72
How do you convert from m to nm?
X q000000000
73
How do you convert from nm to m?
Divide by 1 000 000 000
74
How do you convert from m to pm
X 1000000000000
75
What is simple diffusion?
The net movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
76
What molecules enter and leave cells via simple diffusion through the cell membrane?
Small molecules
77
What factors affect the rate of diffusion?
Temperature Concentration gradient Surface area of cell membrane
78
Define osmosis
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
What is active transport?
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
How is a percentage change in mass calculated?
(Final mass - initial mass / initial mass) x 100

Biology (8 decks)

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