B4 - The Processes of Life Flashcards
1
Q
What are cells?
A
The building blocks of all living things.
2
Q
What do all cells contain? (2 things)
A
- DNA
- Organelles
3
Q
What are DNA molecules in the form of?
A
A double helix
4
Q
What does DNA contain?
A
Genetic code
5
Q
What are organelles?
A
The different parts of the cell’s structure. They do different jobs within the cell and work together to allow the cell to perform a specific function.
6
Q
What parts do human cells (and most animal cells) contain? (4 things)
A
- Cytoplasm
- Mitochondria
- A nucleus
- A cell membrane
7
Q
What is the cytoplasm?
A
It’s where most chemical reactions take place, including anaerobic respiration, the production of enzymes and other proteins.
8
Q
What is the mitochondria?
A
It contains the DNA that carries the genetic code for making enzymes and other proteins used in all chemical reactions in the cell.
9
Q
What is the nucleus?
A
It contains the DNA that carries the genetic code for making enzymes and other proteins used in all chemical reactions in the cell.
10
Q
What is the cell membrane?
A
It allows chemicals like gases and water to pass in and out freely but prevents other chemicals from leaving or entering the cell.
11
Q
What parts do plant cells have that human and animal cells don’t have?
A
- A cell wall
- A permanent vacuole
- Chloroplasts
12
Q
What is the cell wall of a plant made of?
A
Cellulose
13
Q
What is the purpose of the cell wall of a plant?
A
To strengthen the cell
14
Q
What is the purpose of a permanent vacuole?
A
To help support the cell
15
Q
What do chloroplasts contain?
A
Green pigment chlorophyll (that absorbs light energy), and some enzymes needed for photosynthesis
16
Q
What features do most microbial cells (e.g. bacteria) have?
A
- Cell wall
- DNA
17
Q
What is the difference between the cell wall of a microbial cell and the cell wall of a plant cell?
A
The cell wall of a microbial cell is not made of cellulose but of other material, e.g. protein.
18
Q
What is the difference between DNA of a microbial cell and DNA of a plant cell?
A
The DNA in a microbial cell is in a circular structure and not in a nucleus and not as chromosomes
19
Q
Why is it strange that yeast are referred to as microbial cells?
A
Because yeast cells are much more similar to higher organisms than microbial cells.
20
Q
What happens within the cytoplasm of a bacteria cell?
A
Proteins, including enzymes used in aerobic and anaerobic respiration, are made.
21
Q
Where can the DNA be found in a bacteria cell?
A
Circular DNA can be found floating freely in the cytoplasm
22
Q
What about the cell membrane of bacteria?
A
It allows gases and water to enter and leave the cell freely while acting as a barrier to other, larger chemicals.
23
Q
What happens in the mitochrondia?
A
Aerobic respiration
24
Q
What are enzymes?
A
Protein molecules that speed up the rate of chemical reactions in cells - they are catalysts in living things
25
Cells produce enzymes according to instructions from where?
The instructions carried in genes (DNA code)
26
Enzymes need a specific temperature to do what?
To work at their optimum
27
True or False?
All enzymes have the same optimum temperatures.
False - different enzymes have different optimum working temperatures.
28
At low temperatures, small increases in temperatures cause an _____a)_______ in the frequency and _____b)______ of collisions between reactants and enzymes, so the rate of reaction ____c)_____.
a) increase
b) energy
c) increases
29
a) What happens after the optimum enzyme activity is reached?
b) What is this called? (HT)
a) The enzymes start to get damaged so the reaction starts to slow down. Eventually the enzyme's structure is permanently destroyed and it stops working
b) The enzyme has become denatured.
30
What does the 'lock and key' model represent?
Only a molecule with the correct shape can fit into an enzyme, similar to the way a key (the molecule) fits into a lock (the enzyme).
31
Once the enzyme and molecule are linked, what happens?
- The reaction takes place
- The products are released
- The process is able to start again
32
What is the active site? (HT)
The place where the molecule fits into the enzyme.
33
How can the shape of the active site be changed irreversibly? (2 things) (HT)
- Heating the enzyme above a certain temperature
| - Altering the pH level
34
When the shape of the active site is irreversibly changed, what does it mean? (HT)
That the molecule can no longer fit and the reaction can't take place.
35
What is respiration?
The release of energy from food chemicals in all living cells.
36
What are the two types of respiration?
- Aerobic respiration
| - Anaerobic respiration
37
What does aerobic respiration do?
It releases energy inside living cells by breaking down glucose and combining the products with oxygen.
38
What is the word equation for aerobic respiration?
glucose + oxygen = carbon dioxide + water + energy released
39
What does aerobic respiration need in order to occur?
Oxygen
40
Where does aerobic respiration occur?
Animal cells, plant cells, and many microbial cells.
41
The energy released as a result of aerobic respiration is used in many chemical reactions. Give 3 examples of these reactions.
- Movement, e.g. the contraction of muscles when running
- The synthesis/making of large molecules from smaller ones, e.g. chlorophyll from glucose
- Active transport of some chemical molecules across a cell membrane (HT)
42
What is the symbol equation for aerobic respiration?
C[6]H[12]O[6] + 6O[2] = 6CO[2] + 6H[2]O + energy released
43
What does anaerobic respiration do?
It releases energy inside the cytoplasm of living cells by breaking down glucose molecules without the use of oxygen.
44
What is the word equation for anaerobic respiration:
a) in plant cells and in some microbial cells (e.g. yeast)?
b) in animal cells and in some bacteria?
a) glucose = carbon dioxide + ethanol + energy released
| b) glucose = lactic acid + energy released
45
In what sort of conditions does anaerobic respiration occur?
In conditions of very low oxygen or where no oxygen is present.
46
Give some examples of where anaerobic respiration could occur.
- When plant root cells are in waterlogged soil, e.g. rice plants
- In human muscle cells during vigorous exercise, e.g. a 100m sprint
- In bacterial cells inside a puncture wound
47
Which method of respiration is more efficient? Why?
Aerobic respiration is much more efficient than anaerobic respiration because it releases much more energy per glucose molecule.
48
How much more energy per glucose molecule does aerobic respiration release than anaerobic respiration?
19 times more
49
What is the function of mitochondria in a cell?
They contain the enzymes for aerobic respiration
50
What are the three structures found in plant cells but not in animal cells?
Cell wall, chloroplasts, permanent vacuole.
51
Give some examples of uses of anaerobic respiration. (4)
- It provides a little more energy to cells when very necessary (e.g. to limb muscles when running away from danger)
- In sewage farms, anaerobic microbes can be added to solid matter, and they can break down the sewage and release methane gas, which is collected. This gas (now called biogas) is burned to heat water to turn electricity generators. Biogas can also be used as a fuel to replace petrol in vehicles.
- Anaerobic respiration in yeast is used in baking. Yeast in bread dough releases carbon dioxide gas, which makes the dough rise before baking
- Anaerobic respiration in yeast is also used in brewing to produce alcohol (ethanol) in wines and beers = fermentation. If oxygen gets in, the yeast stops respiring anaerobically and the alcohol turns to vinegar (ethanoic acid), which ruins the product.
52
How can anaerobic respiration be used in sewage farms?
In sewage farms, anaerobic microbes can be added to solid matter, and they can break down the sewage and release methane gas, which is collected. This gas (now called biogas) is burned to heat water to turn electricity generators. Biogas can also be used as a fuel to replace petrol in vehicles.
53
How can anaerobic respiration be used in baking?
Anaerobic respiration in yeast is used in baking. Yeast in bread dough releases carbon dioxide gas, which makes the dough rise before baking
54
How can anaerobic respiration be used in brewing?
Anaerobic respiration in yeast is also used in brewing to produce alcohol (ethanol) in wines and beers = fermentation. If oxygen gets in, the yeast stops respiring anaerobically and the alcohol turns to vinegar (ethanoic acid), which ruins the product.
55
How is glucose produced?
Through photosynthesis in plants
56
Glucose can be built up into a ___________ as cellulose or as starch
polymer
57
Glucose can be built up into a polymer as what two things?
Cellulose or starch
58
What is the use of a glucose polymer in cellulose?
To build up cell walls
59
What is the use of a glucose polymer in starch?
For storage in roots
60
What is a polymer?
A long-chain molecule made from copies of the same unit
61
What two things can be joined together to make larger molecules called amino acids?
Glucose and nitrates
62
What can amino acids be joined together to create?
Proteins (polymers of amino acids) in plant, animal, and bacterial cells
63
In what three stages does photosynthesis take place?
- Light energy is absorbed by chlorophyll in green plants
- Within the chlorophyll molecule, the light energy is used to rearrange the atoms of carbon dioxide and water to produce glucose (a sugar)
- Oxygen is produced as a waste product
64
How is light energy absorbed into plants during photosynthesis?
Through chlorophyll in green plants
65
What is light energy used to do in the process of photosynthesis?
Light energy is used to rearrange the atoms of carbon dioxide and water to produce glucose (a sugar)
66
What is produced as a waste product in the process of photosynthesis?
Oxygen
67
What is the word equation for photosynthesis?
carbon dioxide + water (through light energy and chlorophyll) = glucose + oxygen
68
What is the symbol equation for photosynthesis? (HT)
6CO[2] + 6H[2]O (through light energy and chlorophyll) = C[6]H[12]O[6] + 6O[2]
69
What are the three factors that can affect/limit the rate of photosynthesis?
- Temperature
- Carbon dioxide concentration
- Light intensity
70
a) Why can it be hard to obtain accurate measurements of the rate of photosynthesis?
b) So what CAN the measurements tell us?
a) Because it's difficult to measure without altering one of the limiting factors. Factors that affect photosynthesis are difficult to control, e.g. wind or moisture levels.
b) Measurements only INDICATE the rate of photosynthesis rather than give a definite rate
71
How does temperature affect the rate of photosynthesis?
- As the temperature rises, so does the rate of photosynthesis. So, temperature is limiting the rate of photosynthesis.
- As the temperature reaches 45 degrees celsius, the enzymes controlling photosynthesis start to be destroyed (denatured) and the rate of photosynthesis drops to zero
72
How does carbon dioxide concentration affect the rate of photosynthesis?
- As the carbon dioxide concentration rises, so does the rate of photosynthesis. So, carbon dioxide is limiting the rate of photosynthesis.
- Once the carbon dioxide levels reach a certain amount, they will no longer have any effect. Carbon dioxide is no longer the limiting factor - it must either be light or temperature.
73
How does light intensity affect the rate of photosynthesis?
- As the light intensity increases, so does the rate of photosynthesis. So, light intensity is limiting the rate of photosynthesis.
- Once the light intensity levels reach a certain amount, they will no longer have any effect. Light intensity is no longer the limiting factor - it must either be carbon dioxide or temperature.
74
a) How can data be collected in the field to investigate how light can affect plants?
b) What are these techniques used to ensure?
a) - Light levels can be measured using a light meter
- Plants can be identified using an identification key
- Plants are chosen at random by using a quadrat and transect
b) To ensure that the data produced is representative of the area but is also random to avoid any bias in the findings.
75
What is a quadrat?
Anything with a defined, e.g. a half metre square, which is placed at intervals along the transect line randomly to sample the area.
76
What is a transect?
A random section across an area, e.g. a line or measured band, which is used to represent the entire area.
77
What is diffusion?
The overall movement of substances from regions of high concentration, to regions of low concentration.
78
How are oxygen and carbon dioxide exchanged in the leaf?
By diffusion of the gases in and out.
79
Substances that move in and out of cells by diffusion can include what?
Oxygen, carbon dioxide and dissolved food
80
What two gases are exchanged in the leaf by diffusion of the gases in and out?
Oxygen and carbon dioxide.
81
What do plants need to absorb from the soil for healthy growth? (HT)
Nitrates
82
Why do plants need to absorb nitrates from the soil? (HT)
For healthy growth
83
a) How do plants normally absorb nitrates from the soil?
b) Why is this a problem?
c) So what actually happens as a result? (HT)
a) Diffusion
b) Because the concentration of nitrates outside the plant is lower than the inside (whereas diffusion is movement of substances from high concentration to low concentration)
c) Therefore a plant has to use energy from respiration to absorb nitrates from active transport
84
What is active transport? (HT)
The movement of a substance against a concentration gradient (i.e. from a region of low concentration to a region of high concentration).
85
What does active transport require in order to happen? (HT)
Energy from respiration
86
Explain what would happen in this example of active transport. (HT)
If the concentration of glucose inside a cell is higher than the concentration outside the cell...
...the glucose would diffuse out of the cell along the concentration gradient, so cells use active transport to bring all of the glucose back inside the cell.
87
What is osmosis a type of?
Diffusion
88
What is osmosis?
It's the overall movement of water from a dilute solution to a more concentrated solution through a partially permeable membrane.
89
a) What does a membrane allow to pass through?
b) What does it not allow to pass through?
c) Why can't b) pass through?
a) Water molecules
b) Solute molecules
c) Because they are too large
90
Water moving due to osmosis gradually __________ the concentrated solution.
Dilates
