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GCSE biology > Topic 1: Key Concepts > Flashcards

Topic 1: Key Concepts Flashcards

1
Q

What are the two types of cells?

A

Eukaryotic (animals and plants) and prokaryotic

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2
Q

What is the difference between an eukaryotic and prokaryotic cell?

A

An eukaryotic cell contains a nucleus and membrane-bound organelles, a prokaryotic cell doesn’t

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3
Q

What are the components of both plant and animal cells?

A

Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes

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4
Q

How is genetic information stored in an eukaryotic cell?

A

Within the nucleus, arranged in chromosomes

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5
Q

What is the function of the nucleus?

A

Storing genetic information and controls cellular activities

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6
Q

What is the structure of the cytoplasm?

A

Fluid component of the cell and contains organelles, enzymes dissolved ions and nutrients

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7
Q

What is the function of the cytoplasm?

A

Site of cellular reactions

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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

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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 and chloroplast

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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 and prevents the bursting when water enters by osmosis

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14
Q

What does the 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 photosynthesis

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17
Q

Why do chloroplast appear green?

A

Contain chlorophyll which is a green pigment

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18
Q

What organelles are found in prokaryotic cells?

A

Chromosomal DNA, plasmid DNA, cell wall, cell membrane, ribosomes and 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 or plasmid DNA

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20
Q

What are plasmid?

A

Small, circular loops of DNA found free in the cytoplasm and separated from the main DNA, they also carry genes that provide genetic advantages

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21
Q

What is the prokaryotic cell wall composed of?

A

Peptidoglycan

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22
Q

What is a flagellum?

A

Long, rotating ‘whip-like’ protrusion and 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

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24
Q

What is a diploid cell?

A

A cell that contains two copies of each chromosome

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25
What are gametes?
Reproductive and haploid cells
26
What is sexual reproduction in terms of chromosome number?
Two haploid gametes fuse resulting embryo has two chromosomes for each gene and two copies of each allele
27
How are egg cells 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 and cell membrane hardens after fertilisation, preventing the entry of other sperm and ensuring the zygote is diploid
28
How are spermicide cells adapted to their function?
Haploid nucleus contains genetic information, tail enables movement, mitochondria provide energy for tail movement and acrosome contains enzymes that digest the egg cell membrane
29
Where are ciliated epithelial cells found?
Found lining the surface
30
What is the function of ciliated epithelial cells lining the airways?
Move in synchronised waves to beat mucus (containing dirt and pathogens) up to the back of the throat where it can be swallowed
31
What is magnification?
The number of times bigger an image appears compared to the size of the specimen
32
How can the total magnification of an image be calculated from lens powers?
Total magnification = eyepiece lens magnification x objective lens magnification
33
How can the magnification of an image be calculated?
Size of image / size of specimen
34
What is resolution?
The smallest distance between two objects that can be distinguished
35
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
36
What are the advantages of light microscopes?
Inexpensive, easy to use, portable and observe both dead and living specimens
37
What is the disadvantage of light microscopes?
Limited resolution
38
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
39
What are the two types of electron microscope?
Transmission electron microscope (TEM) and scanning electron microscope (SEM)
40
What are the advantages of electron microscopes?
Greater magnification and resolution
41
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
42
How have electron microscopes enabled scientists to develop their understanding of cells?
Allow small sub-cellular structures to be observed in detail and enable scientists to develop more accurate explanations about how cell structures relates to function
43
What are the disadvantages of electron microscopes?
Expensive, large so less portable, require training to use and only dead specimens can be observed
44
How do you convert meters to millimetres?
x 1000
45
How do you convert meters into micrometers?
x 1,000,000
46
How do you convert meters to nanometers?
x 1,000,000,000
47
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
48
What molecules enter and leave cells via simple diffusion through the cell membrane?
Small molecules e.g oxygen, water, glucose and amino acids
49
What factors affect the rate of diffusion?
Temperature, concentration gradient and surface area of cell membrane
50
What is 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
51
What is active transport?
The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration, again the concentration gradient, using energy
52
How is the percentage change in mass calculated?
Percentage change = (final mass - initial mass) / initial mass x 100
53
What are enzymes?
Biological catalysts that increase the rate of a chemical reaction with being permanently altered themselves
54
What is an advantage of enzymes in the body?
They enable cellular reactions to take place at lower temperatures
55
What is the active site of an enzyme?
The region of an enzyme to which a substrate molecule binds and the reaction takes place
56
Why are enzymes described as having a ‘high specific’ for their substrate?
Only substrates with a specific, complementary shape can fit into an enzyme’s active site
57
What is the ‘lock and key’ model?
Substrate collides 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
58
What factors affect the rate of an enzyme-controlled reaction?
Temperature, pH and substrate concentration
59
How does increasing temperature initially affect the rate of an enzyme-controlled reaction?
As temperature increases molecules have more KE, movement of molecules increases, probability of a successful collision increases, more enzyme-substrate complexes form and rate of reaction increase
60
How does increasing temperature above the optimum affects the rate an enzyme-controlled reaction?
Temperature increases above the optimum, increased vibration break bonds in enzyme’s structure, active site changes shape, enzyme is denatured, no more enzymes-substrate complexes can form and rate of reaction decreases
61
Explain how pH affects the rate of an enzyme-controlled reaction?
Enzymes have an optimum pH, pH shifts from the optimum, bonds in the enzyme’s structure are altered, active site change shape, enzyme is denatured, rate of reaction decreases
62
How does the substrate concentration affects the rate of an enzyme-substrate?
Substrate concentration increases, number of substrate molecules in the same volume increases, probability of a successful collision increases, more enzymes-substrate complexes form, rate of reaction increases and once all the active sites become full, the rate of reaction plateaus
63
How can the rate of an enzyme-controlled reaction be calculated when given a value for time?
1/time
64
What are the units for rate?
S-1
65
Why must large organic molecules broken down into smaller, simpler molecules in the body?
Large molecules are too big to be absorbed across the surface of the gut wall and large molecules are broken down into smaller molecules for absorption into the bloodstream
66
What type of molecules are proteins and carbohydrates?
Polymers
67
What are the monomers of carbohydrates?
Simple sugars
68
Which group of enzymes catalysts the breakdown of carbohydrates?
Carbohydrases
69
Which type of carbohydrases catalysts the breakdown of starch?
Amylase
70
What are the monomers of proteins?
Amino acids
71
Which group of enzymes catalysts the breakdown of protein?
Proteases
72
What is the function of lipases?
Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol
73
Why are small molecules synthesised into larger organic molecules in the body?
Large molecules are used for storage or are used to build structures
74
Which group of enzymes catalysts the formation of glucogen from glucose?
Glycogen synthase
75
How can the amount of energy contained in food be measured?
Measured using calorimetry
76
What is calorimetry?
A method of measuring the heat transfer during a chemical reaction
77
What is the method used to measure the amount of energy in a sample of food?
Add a set volume of water to a boiling tube, record initial temperature, record the mass of a small sample of food, stick the sample onto a mounted needle, using a bunsen burner light the food sample. Hold the sample under the boiling tube until it burns up, record the maximum temperature reached by the water and record the final mass of the food sample
78
How can the amount of energy in the food sample be calculated?
Energy in food = mass of water x temperature change of water x 4.2

GCSE biology (9 decks)

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