Topic 1 - Key Concepts Of Biology Flashcards
1
Q
What are all living organisms made of ?
A
cells
2
Q
What are cells ?
A
Cells are the basic unit of living organisms
3
Q
What are the two diferent types of cells called ?
A
Eukaryotic cells
Prokaryotic cells
4
Q
What are the size of prokaryotic cells ?
A
Prokaryotic cells are 0.1 - 5.0 micrometres in size.
5
Q
Whats a prokaryote ?
A
is an organism made up of prokaryotic cells.
6
Q
Whats an example of a prokaryote ?
A
Bacteria
7
Q
What is the size of eukaryotic cell ?
A
They are 10 - 100 micrometres in size.
8
Q
What is a eukaryote ?
A
A eukaryote is an organism made up of eukaryotic cells
9
Q
Where are eukaryotic cells found ?
A
plants, animals, fungi and protists (single-celled organisms that don’t fit other categories).
10
Q
What are the key features of prokaryotic cells ?
A
Plasmids
No mitochondria or chloroplasts
Single loop DNA - Prokaryotic cells do not have a nucleus (where DNA is stored).
Instead, most of their genetic material is stored in a single DNA loop in the cytoplasm (watery jelly that fills the cell).
11
Q
What are plasmids ?
A
Small rings of DNA - Prokaryotic cells may have one or more small rings of DNA, which are called plasmids.
These plasmids can replicate (have copies made) and move between cells so that genetic information can be shared.
12
Q
Where is the genetic material of prokaryotes found ?
A
is stored in a single DNA loop in the cytoplasm (watery jelly that fills the cell).
13
Q
A scientist finds cells with different diameters. What measurement is likely to be that of a prokaryotic cell?
A
0.1-5.0 micrometers
14
Q
What are Sub-cellular structures missing from prokaryotic cells that are found in eukaryotic cells ?
A
Nuclues
Mitochondria
Chloroplasts
15
Q
What are sub-cellular structures ?
A
Sub-cellular structures are things found in a cell
16
Q
What are the sub-cellular structures found in animal cells ?
A
Cell membrane Nucleus Ribosomes Mitochondria Cytoplasm
17
Q
What are the features of the cytoplasm ?
A
Cytoplasm is a jelly-like fluid that fills the cell.
It is where most of the cell’s chemical reactions take place
18
Q
What are the features of the mitochondria ?
A
Mitochondria produce energy.
Aerobic respiration (process which uses sugar and oxygen to release energy) releases energy in the mitochondria
19
Q
Whats the function of ribosomes ?
A
Ribosomes are responsible for synthesising (making) proteins.
Protein sythesis
20
Q
What is the function of the cell membrane in an animal cell ?
A
The cell membrane separates the interior (inside) of the cell from the environment outside.
It is selectively permeable (it can control substances moving in and out of the cell).
21
Q
What is the function of the nucleus in an animal cell ?
A
The nucleus is the control centre of the cell.
It contains chromosomes (which contain the cell’s genetic material)
22
Q
In addition to the sub-cellular structures found in an animal cell, a typical plant cell also has what sub-cellular structures ?
A
Permanent vacuole
Chloroplasts
Cell wall
23
Q
What is the function of the permanent vacuole ?
A
A permanent vacuole is a fluid-filled sac that stores water.
It is enclosed in a membrane (a wall that substances can pass through).
It can make up as much as 90% of a plant cell’s volume.
24
Q
What is the function of chloroplasts ?
A
Chloroplasts contain chlorophyll, which is needed for the process of photosynthesis
25
What is function of the cell wall ?
The cell wall surrounds the cell and is made of cellulose.
The cell wall increases the structural strength of the cell.
26
How many more sub-cellular structures do plant cells have then animal cells ?
3
27
What sub-cellular structures are found in bacteria cells ?
```
Flagella
Cell wall
Cell membrane
Ribosomes
Cytoplam
Plasmids
```
28
What is the function of the flagella ?
These are whip-like structures used for movement
29
What are sperm cells specialised to do ?
Sperm cells are specialised to fertilise egg cells.
30
What do sperm cells do ?
To do this, they need to travel long distances relative to their size.
They then break through to the egg cell and fertilise it (combine the sperm DNA with the egg DNA).
31
What are the adaptations sperm cells have made to perform thir function ?
The middle part of the cell contains lots of mitochodria
They have a tail
Has a head
The head contains acrosome
32
Why does the middle section of a sperm cell contain lots of mitochondria ?
to provide the sperm with the energy it needs to travel a long distance to reach the egg cell
33
Why has a sperm cell got a tail ?
The ‘tail’ is used for the cell’s motion - this allows sperm cells to travel towards the egg cell.
34
What does the ‘head’ of the sperm cell contain ?
The ‘head’ contains the sperm cell’s nucleus.
35
What does the nucleus of a sperm cell contain ?
The nucleus carries one half of an organism’s genetic material.
36
What does the nucleus of a sperm cell combine with to fertilise the egg cell ?
This combines with the egg cell's half of genetic material to fertilise the egg cell.
37
Why does the tip of the sperm cells ‘head’ contain acrosome ?
The acrosome at the tip of the head contains an enzyme needed to penetrate (break into) an egg cell.
38
What does magnification tell us ?
how many times larger an image seen through a microscope is compared to the real object.
39
What is resolution ?
The ability to distinguish between (tell apart) two or more objects that are close together.
40
What is a magnification of x240 000 in standard form?
2.4 x 10^5
41
What do enzymes do ?
Enzymes increase the speed of reactions
42
What are enzymes known as ?
They are often called biological catalysts
43
To catalyse (speed up) a reaction what must the reacting chemical (substrate) bind to ?
To catalyse (speed up) a reaction, the reacting chemical (substrate) must bind to the enzyme's active site.
The active site will only fit specific substrates
44
Fact
The active site is like a lock and the substrate is like a key.
In the same way, there is usually only one enzyme for every substrate (or one key for each lock).
45
What are factors that affect the rate (speed) of enzyme action ?
Temperature
pH (measure of acidity)
Substrtae concentration
46
How does temperature affect enzyme action .
Increasing the temperature of a working enzyme initially increases the reacting activity.
Enzymes have an optimum temperature. After this temperature, the activity decreases.
Past a certain temperature, the active site changes shape, and the enzyme is denatured (loses its catalytic activity).
47
How does pH affect enzyme action ?
Enzymes have an optimum pH (measure of acidity).
If the pH changes away from the optimum pH, then the enzyme activity decreases.
If the pH is too low or too high, then the enzyme is denatured and will not function.
48
How does substrate concentration affect enzyme action ?
Increasing the substrate concentration will increase the rate of activity to a certain point until it levels off.
This is because if there are more substrate molecules available for the enzyme to bind to, the rate increases.
But once there are enough substrate molecules for all the enzymes to bind to, increasing the
substrate concentration any more will have no effect on the rate of activity.
49
How do you calculate rate of reaction ?
The rate of reaction is equal to the gradient of the graph, which shows the mass of the product plotted against the reaction time.
The gradient is calculated by picking two points on the graph, then dividing the change in the value on the y-axis (mass) by the change in the x-axis value (time), between those two points.
In the example above, the rate of reaction = 10g ÷ 60s = 0.17 g/s.
50
Rate of reaction = ? ÷ ?
Rate of reaction = change in mass (g) ÷ change in time (h)
51
A small plant produces (makes) 10g of a substance in 5 hours. What is the rate of reaction?
Remember the equation for reaction rate
Rate of reaction = change in mass (g) ÷ change in time (h)
Substitute the values in
Rate of reaction = 10g ÷ 5h
Work out the answer, remembering to include the appropriate units
Rate of reaction = 2 g/h
52
What is the effect of pH on amalyse ?
Amylase breaks down starch, which can be detected using iodine solution
53
How can you find amylase's optimal pH ?
Add amylase to starch solution.
Every 30 seconds, take a drop of the mixture and add a drop of iodine solution.
Record the total time taken for the iodine solution to stop turning blue when added (which indicates that all the starch has been broken down).
Repeat this experiment using starch solutions with different pHs.
The shorter the time taken for the iodine to stop changing colour, the faster the amylase has broken down the starch and the closer this pH is to amylase's optimal pH.
54
What are the dependent and independent variables in the experiment investigating the effect of pH on amylase?
The independent variable is the pH
The dependant variable is the time taken for the starch to be broken down
55
Using a starch solution with a pH closer to the optimum pH of amylase, how long will it take for the iodine to no longer turn blue when added?
More time
The same length of time
Less time
Less time
56
Gradient = ? / ?
Gradient = change in y / change in x
57
reaction rate= ? / ?
|
reaction rate= change in mass / change in time
58
How are digestive enzymes produced ?
Digestive enzymes are produced by specialised cells (perform a specific function) in the glands and the lining of the gut
They are then secreted (released) out of the body cells and into the cavity of the digestive system
59
What are digestive enzymes used for ?
Breaking down large food molecules
60
How do digestive enzymes break down large food molecules ?
The digestive enzymes catalyse (speed up) the breakdown of large, insoluble food molecules into smaller, soluble (can be dissolved) molecules that are then small enough to be absorbed into the bloodstream.
Digested molecules can be used to construct new carbohydrates, proteins and lipids in the body.
Some glucose produced by digestion is used for respiration
61
What are the three main digestive enzymes ?
Amylase
Protease
Lipase
62
What do carbohydrases do ?
Carbohydrases break carbohydrates down into sugars.
63
Amylase is a type of what that breaks down starch in our bodies ?
Amylase is a type of carbohydrase that breaks down starch in our bodies
64
What is the purpose of amalase ? (What does Amylase breaks down starch into)
Amylase breaks down starch into its constituent simple sugars (predominantly maltose).
Starch → Maltose (+ other sugars).
65
Where is amylase produced ?
Small intestine
Pancreas
Salivary glands
66
Where are The sites of action for amylase ?
The small intestine
| The mouth
67
Proteases are digestive enzymes that break down proteins into what ?
Proteases are digestive enzymes that break down proteins into amino acids.
68
Where are Proteases produced ?
small intestine
pancreas
stomach
69
Where are the action sites for proteases ?
small intestine
| stomach
70
What is the purpose of proteases ?
Proteases break down proteins into amino acids.
| Protein → Amino acids.
71
Amylase breaks starch down mainly into what ?
Maltose
72
Lipase is a type of digestive enzyme that breaks down lipids into what ?
Lipase is a type of digestive enzyme that breaks down lipids into glycerol and fatty acids.
73
Where is lipase produced ?
Small intestine
| Pancreas
74
Whats the purpose of lipase ?
Lipase breaks down lipids into a molecule called glycerol and fatty acids.
Lipid → Glycerol + Fatty Acids.
75
What can be used to test for the presence of various food substances ?
Reagents can be used to test for the presence of various food substances.
76
What is the first step for the reagents test ?
The first step is to grind up the food and add distilled water to dissolve some of the food. You can then test for the food substances
Lipids
Proteins
Starch
Sugar
77
How can you test for lipids ?
To test for lipids, add ethanol and water and shake.
If lipids are present, a white emulsion (cloudy liquid) will form.
78
What do we use to test the calorie content of foods ?
Calorimetry
79
How does caloimetry work
Burn a known mass of the food under a boiling tube filled with a known volume of water.
Calculate the change in temperature of the water.
80
How do we test for proteins ?
To test for proteins, add Biuret solution.
It will turn mauve or purple if proteins are present.
81
How do you test for starch ?
To test for starch, add iodine solution.
It will turn blue-black if starch is present.
82
How do you test for sugars ?
To test for sugar, add Benedict’s reagent and heat for about two minutes.
It will turn any of green, yellow or red if sugar is present.
The colour depends on the concentration.
83
What does the small intestine do?
Produces digestive enzymes
Digests food
Absorbs soluble food molecules
84
Which part of the enzyme binds with the substrate?
Active site
85
What is diffusion
Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration.
It describes the movement of particles in fluids (liquids and gases).
86
How can Substances move in and out of cells across cell membranes ?
Substances can move in and out of cells across cell membranes via diffusion.
87
Fact
Urea, a waste product of cells, diffuses out of cells and into the blood for excretion by the kidneys.
88
The rate of diffusion can speed up or slow down based on what factors ?
Concentration gradient
Temperature
Membrane surface area
89
How does concentration gradient affect rate of diffusion ?
The concentration gradient is linked to the difference in concentration between two areas.
The bigger the difference in concentration between two areas, the greater the concentration gradient and the faster the rate of diffusion
90
How does temperature affect rate of diffusion ?
The higher the temperature, the faster the rate of diffusion.
91
How does membrane surface area affect rate of diffusion ?
The larger the surface area of the membrane that a substance is diffusing through (e.g. the membrane around a cell), the faster the rate of diffusion.
92
Small organisms normally have a higher surface area to what ratios than large organisms ?
Small organisms normally have a higher surface area to volume ratios than large organisms.
This means that diffusion can happen through a large area of small organisms.
This makes diffusion useful for transporting molecules through a small organism.
93
How does surface area to volume ratio affect the rate of diffusion ?
The higher the surface area to volume ratio, the higher the rate of diffusion.
94
What is a waste product removed during diffusion at the lungs?
CO2
95
Whats am example of surface are to volume ratio ?
A fennec fox has a large surface area to volume ratio, allowing it to lose heat quickly in the desert.
96
What is osmosis ?
Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high concentration of water) to a concentrated solution (low concentration of water).
97
Why is a partially permeable membrane needed for osmosis ?
A partially permeable membrane allows water through, but won't let larger molecules dissolved in water pass through
98
During osmosis what will move to make the concentrations the same on both sides of the membrane ?
Water will move to make the concentrations the same on both sides of the membrane
99
When there are lots of water molecules (in a dilute solution) on one side of a partially permeable membrane, but not many on the other side (in a concentrated solution) what will the water do ?
water will move from the dilute to the concentrated solution.
100
How do water molecules move during osmosis ?
It is important to remember that water molecules will move through the membrane in both directions, but the net (overall) movement of water will be from the dilute solution to a concentrated solution.
101
What is a specialised plant tissue that uses osmosis to absorb water?
Root hair cell
102
Whats an independent variable ?
A variable that you control - it is changed to see how the dependent variable will change
103
Whats a dependent variable ?
A variable that you measure as an outcome of an experiment
104
In osmosis what is the independent variable ?
The concentration of the sugar solution
105
In osmosis what is the dependent variable ?
Mass of the object being used
106
What is the experiment to show the effect of water concentration on osmosis ?
Cut discs of raw potato and measure their mass.
Put discs in different concentrations of sugar or salt solution.
After 30 minutes, measure the mass of each disc again
Subtract the final mass by the initial mass of each disc.
Divide this number by the initial mass and then multiply by 100 to give a percentage change in mass.
The concentration in which the potato's mass changed the least is closest to the water concentration of the potato (because the least water has moved into or out of the potato by osmosis).
107
The mass of a potato cylinder is 80g before being left in a solution and 100g afterwards. What is the percentage change in mass of the cylinder?
% change in mass = ((final mass - initial mass) ÷ initial mass) x 100
% change in mass = ((100-80) ÷ 80 ) x100
% change in mass= (20 ÷ 80) x 100
% change in mass= (0.25) x 100
% change in mass= 25%
108
The change of mass in the osmosis experiment is worked out by which equation?
Final mass - initial mass
109
What is active transport used in ?
Sugar absorption in human gut
Mineral absorption in plants
110
How is active transport used in Sugar absorption in human gut ?
Active transport allows sugar molecules, which are needed for cell respiration, to be absorbed into the blood from the gut, even when the sugar concentration of the blood is higher.
111
How is actove transport used in Mineral absorption in plants ?
Active transport in the root hairs of plants allows plants to absorb mineral ions, which are necessary for healthy growth, even though the concentration of minerals is usually lower in the soil than in the root hair.
112
What is active transport ?
The process where dissolved molecules move from less concentrated solutions to more concentrated solutions.
As the net movement of molecules is against the concentration gradient, energy is required.
This energy is provided by respiration
113
What are the three main forms of transport in cells ?
Diffusion
Osmosis
Active transport
114
What are forms of active transport ?
Diffusion
| Osmosis
