Topic 1 - Key Concepts in Biology Flashcards
(183 cards)
1
Q
What can organisms be?
A
Eukaryotes and prokaryotes
2
Q
All living things are made up of tiny ____
A
All living things are made up of tiny cells
3
Q
What are eukaryotic cells?
A
Complex cells
4
Q
Give examples of types of organisms with eukaryotic cells
A
Plants and animals
5
Q
What are prokaryotic cells?
A
Smaller and simpler cells
6
Q
Give examples of types of organisms with prokaryotic cells
A
Bacteria
7
Q
What are eukaryotes?
A
Organisms made of eukaryotic cells
8
Q
What are prokaryotes?
A
Prokaryotic cells (single-celled organism)
9
Q
What are the differents parts of a cell?
A
Subcellular structures
10
Q
Give examples of subcellular structures in animals cells?
A
A nucleus Cytoplasm A cell membrane Mitochondria Ribosomes
11
Q
What is a nucleus?
A
A subcellular structure that contains genetic material that controls the activites of the cell
12
Q
What is cytoplasm?
A
A gel-like substance where most of the chemical reactions happen
13
Q
What can be found in the cytoplasm?
A
Enzymes
14
Q
What is the cell membrane?
A
The membrane around the cell which holds the cell together and controls what goes in and out of the cell
15
Q
What are mitochondria?
A
The place where most reactions for respiration take place
16
Q
What are ribosomes?
A
The structure involved in the translation of genetic material in the synthesis of proteins
17
Q
What are the subcellular structures found with plant cells?
A
A nucleus, cytoplasm, a cell membrane, mitochondria, ribosomes, a cell wall, a vacuole and chloroplasts
18
Q
What is the cell wall?
A
A wall around the cell made of cellulose which supports and strengthens the cell
19
Q
What is the vacuole?
A
A structure which contains cell sap, a weak solution of sugar and salts.
It also helps maintain internal pressure of the cell
20
Q
What are chloroplasts?
A
Structures where photosynthesis occurs which makes glucose for the plant
21
Q
What do chloroplasts have inside them?
A
A green substance called chlorophyll
22
Q
Bacterial cell’s have no _____
A
Bacterial cell’s have no nucleus
23
Q
Bacterial cell’s have ____ nucleus
A
Bacterial cell’s have no nucleus
24
Q
Compare the size of bacterial cells to animal and plant cells
A
Bacterial cells are a lot smaller than plant and animal cells
25
What are the subcellular structures found within bacterial cells
```
Chromosomal DNA
Ribosomes
A cell membrane
Plasmid DNA
A flagellum
```
26
What is chromosomal DNA?
One long circular chromosome which controls the cell's activities and replication
It floats free in the cytoplasm (not in a nucleus, as there is no nucleus)
27
What is plasmid DNA?
Small loops of extra DNA that aren't part of the chromosome
28
What does plasmid DNA contain genes for?
Drug resistance
29
True or False? Bacteria can't pass genes as there are no genes?
False, plasmid DNA can be passed between bacteria
30
What is a flagellum?
A long, hair-like structure that rotates to make the bacterium (enables cell movement)
31
What is the use of a flagellum for a bacterium?
To move the bacteria away from harmful substances like toxins and towards beneficial things like nutirents or oxygen
32
Describe the function of the nucleus
Contains the genetic material that controls the activity of the cell
33
Describe the function of the mitochondria
Where most of the reactions for respiration take place
34
Describe the function of ribosomes
The structure involved in the translation of genetic material in the synthesis of proteins
35
True or false? Multicellular organisms contain lots of different types of cells?
True
36
What are specialised cells?
Cells that have a structure which makes them adapated to their function
37
Give examples of specialised cells?
Egg, sperm and ciliated epithelial cells
38
What are sperm and egg cells specialised for?
Reproduction
39
Why is it important the egg and sperm clel have the right number of chromosomes?
So the fertilised egg has the normal amount for a human
| If not, the offspring will have a disabillity
40
What is the main function of an egg?
To carry the female DNA and to nourish the developing embryo in it's early stages
41
How is the human egg cell adapted to its function?
By containing nutrients in the cytoplasm to feed the embryo
By having a haploid nucleus
Straight after fertillisation its membrane changes structure to stop any more sperm getting in. This makes sure the offspring ends up with the right amount of DNA
42
What is the main function of a sperm cell?
To transport the male's DNA to the female's egg
43
How is the sperm cell adapted to its function?
By having a long tail so it can swim
By having a lots of mitochondria in the middle section to provide the energy needed to swim
By having an acrosome at the front of the head where it stores enzymes needed to digest through the membrane of the egg cell
By having a haploid nucleus
44
What are ciliated epithelial cells specialised for?
Moving materials
45
Where can ciliated epithelial cells be found?
On the lining of organs
46
What do ciliated epithelial cells often have on the surface?
Cillia
47
What are cillia?
Hair-like structures
48
How is ciliated epithelial cells adapted to its function?
The cillia beat to move substances in one direction
| Found in areas of high traffic (lining of the airways)
49
What are cells often studied using?
Microscopes
50
How do microscopes work?
They use lenses to magnify images
51
What are the main goals of microscopes?
To magnify and increase the resolution of the image
52
Define resolution
How well a microscope can distinguish between two points that are close together
53
How do light microscopes work?
By passing light through the specimen
54
What can you see with a light microscope?
Nuclei and chloroplasts
55
True or False? You can't look at living specimens through a light microscope because the light will kill them?
False, you can use it to view living specimens
56
How do electron microscopes work?
By firing electrons through the specimen
57
What can you see with an electron microscope?
The internal structure of mitochondria and chloroplasts
58
What can you see with an electron microscope?
The internal structure of mitochondria and chloroplasts
59
What are the rules of scientific drawing?
```
Use a sharp pencil
Draw outlines
Don't colour or shade
Label all the important features
Include the magnificaton used
Include the scale
```
60
What is magnification?
How many times bigger the image is
61
What is the total magnification equation?
Total magnification = Eyepiece lens magnification x Objective lens magnification
62
What is the magnification equation?
Magnification = Image size / Real size
63
State the way to remember the magnification formula?
I AM
| I = A x M
64
What is the standard form for milli?
x10^-3
65
What is the standard form for micrometre?
x10^-6
66
What is the standard form for micro?
x10^-6
67
What is the standard form for nano?
x10^-9
68
What is the standard form for pico?
x10^-12
69
Calculate the length of a cell which has an image size of 7 x 10^-1mm under a magnification of x400
Write you answer in μm
7 x 10^-1mm x 10^3 = 7 x 10^2
Actual size = Image size / Magnification
AS = 7 x 10^2 / 400
AS = 1.75 μm
70
What are enzymes?
Catalysts produced by living things
71
Why do organisms need enzymes?
Because the reactions need to be carefully controlled, to get the right amount of substances
And the reactions that need to take place require extremely high temperatures which would be impossible within the body
And if you were to raise the temperature, other less useful and sometimes harmful reactions would take place
72
Enzymes have _________ so they can catalyse reactions
Enzymes have special shapes so they can catalyse reactions
73
What do chemical reactions usually involve?
Things being split apart or joined together
74
What is the substrate?
The molecule changed in the reaction (reactant)
75
What does every enzyme have?
An active site
76
What is an active site?
The part where an enzyme joins onto its substrate to catalyse the reaction
77
Enzymes usually only work with ___ substrate
Enzymes usually only work with one substrate
78
What are enzymes said to have for their substrate?
A high specificity
79
Why do enzymes have a high specificity to its enzyme?
Because for the substrate to be catalysed it must fit into the unique enzymes' active site which means that the active site on the enzyme will only fit that substrate
80
What three factors affect the rate of reaction?
Temperature
pH
Substrate concentration
81
How does temperature affect the rate of reaction?
Heating it at first increases the rate, however, too high of temperature will denature the enzyme
82
How does pH affect the rate of reaction?
Too high or too low of a pH will break the bonds holding the enzyme together
There will be an optimum pH at which the enzymes rate is at its fastest
83
How does substrate concentration affect the rate of reaction?
As you increase the concentration of the substrates, the rate of reaction also increases, however, there will be a point where the limiting factor is no longer substrate concentration instead it is now number of open active sites
84
Explain why enzymes have an optimum pH?
If the pH is too high or too low, it can interfere with the bonds holding the enzyme together. This changes the shape of the active site leading to the denaturing of the enzyme
85
When investigating the effect of pH on enzyme activity, what enzyme is used?
Amylase
86
What is amylase?
An enzyme which catalyses the breakdown of starch to maltose (sugar)
87
How do you test for starch?
By using iodine solution
88
What is the colour change when testing for starch?
Browny-orange to blue-black
89
When investigating the effect of pH on enzyme activity, what temperature should you use?
Around 35*c
90
When investigating the effect of pH on enzyme activity, what must you add to a test tube?
```
Amylase solution
Buffer solution (pH of 5)
```
91
When investigating the effect of pH on enzyme activity, why shouldn't you use the same syringe?
Some of the previous chemicals may of not fully left the syringe meaning the reaction will begin early if you were to mix the reactants causing in accurate results
92
When investigating the effect of pH on enzyme activity, what is the main method used?
Continous sampling
93
When investigating the effect of pH on enzyme activity, how do you know when all the starch has been converted?
The iodine solution doesn't change (remains browny-orange)
94
When investigating the effect of pH on enzyme activity, how do you know when all the starch has been converted?
The iodine solution doesn't change (remains browny-orange)
95
When investigating the effect of pH on enzyme activity, what do you change when doing repeats?
The pH of the buffer solution
96
When investigating the effect of pH on enzyme activity, what is the independent variable?
The pH of the buffer solution
97
When investigating the effect of pH on enzyme activity, what is the dependent variable?
Time taken for amylase to break down all of the starch
98
What is the rate of reaction equation?
1000/time
99
What are the units of rate of reaction?What are the units of rate of reaction?
s^-1
100
What is a rate?
A measure of how much something changes over time
101
Examples of big molecules that the body use are ____, ____ and ____
Examples of big molecules that the body use are carbohydrates, lipids and proteins
102
Why is it important that organisms break the larger molecules into smaller molecules?
So they can be used for growth and other life processes
| And some are too big to be moved around the body
103
Give an example of a use that a plants uses starch for
Storage of energy
104
What does a plant do when it needs stored energy?
It's enzymes break down the starch into sugar which can be respired to release
105
What enzymes break down carbohydrates?
Carbohydrases
106
What do carbohydrases break down?
Carbohydrates
107
What do carbohydrates get broken down into?
Simple sugars
108
Give an example of a carbohydrase
Amylase
109
What enzymes break down proteins?
Proteases
110
What do proteases break down?
Proteins
111
What do proteins get broken down into?
Amino Acids
112
What enzymes break down lipids?
Lipases
113
What do lipases break down?
Lipids
114
What do lipids break down into?
Glycerol and fatty acids
115
An enzyme-controlled reaction was carried out at pH 4
After 60 seconds 33cm^3 had been released
Calculate the rate of reaction cm^3 s^-1
33/60=0.55 cm^3 / s^-1
116
Name the molecules that result from the breakdown of carbohydrates
Simple sugars
117
Name the molecules that result from the breakdown of proteins
Amino Acids
118
What do you use to test for sugars?
Benedicts reagent
119
How do you test for sugars?
Add benedicts reagant to the sample and heat it in a water bath thats set to 75*C
If the test is positive a coloured precipitate will form
120
What colour is benedicts reagant before contact with sugar?
Blue
121
State the colour change order for benedicts reagent?
Blue -> Green -> Yellow -> Orange -> Red
122
What is the test for starch?
Iodine
123
How do you test for starch?
Add iodine to the sample
124
Describe the colour change for a positive iodine starch test
From browny orange to bluey black
125
What is the name of the test for lipids?
The emulsion test
126
How do you test for lipids?
Shake the test substance with ethanol for about a minute until it dissolves then pour the solution into water
If lipids are present there will be a milky emulsion
127
Describe the positive test for lipids
Milky precipitate
128
What solutions do you add to proteins?
Potassium hydroxide and copper(ii) sulfate
129
How do you test for proteins?
Add drops of potassium hydroxide to make the solution alkaline
Then add some copper sulfate solution
130
Describe the positive result for the biuret test
If protein is present, solution will turn purple
| If protein not present, solution will remain blue
131
What colour is copper(ii) sulfate?
Blue
132
During the biueret test why do you add potassium hydroxide?
To make the solution alkaline
133
A solution was mixed with potassium hydroxide and copper(ii) sulfate solution turns purple
What conclusion do you draw from this test?
Proteins are present
134
When calculating energy in food, what type of food must you have?
Dry
135
When calculating energy in food, what must you do first?
Weigh the food
136
When calculating energy in food, after weighing the food what must you do?
Add a set volume of water
137
When calculating energy in food, what must you measure?
The temperature of the water before and after
138
When calculating energy in food, where do you hold the burning food?
Underneath the water in the tube with the thermometer
139
How do you calculate the energy in food?
```
E = M x T x 4.2
Energy = Mass x Temperature x 4.2
Joules = g x *c x 4.2
```
140
How do you calculate the energy per gram of food?
Energy per gram of food = Energy in food / Mass of food
| J/g = J / g
141
A student burned 0.2g of popcorn under 20cm^3
During the experiment the temperature of the water increased by 28.6*C when the popcorn was burnt
Calculate the energy per gram of food?
```
E = M x T x 4.2
E = 0.2 x 28.6 x 4.2
E = 2,402.4 J
```
Energy per gram = 2402.4 / 0.2
Energy per gram = 12,012 J/g
142
A student burned 0.5g of popcorn under 20cm^3
During the experiment the temperature of the water increased by 38.7*C when the popcorn was burnt
Calculate the energy per gram of food?
```
E = M x T x 4.2
E = 0.5 x 28.6 x 4.2
E = 3250.8 J
```
Energy per gram = 3250.8 / 0.5
Energy per gram = 6,501.6 J/g
143
A student performed a calorimetry experiement on a small piece of bread
Why is it important to record the increase in temperature as soon as possible after the bread is burnt in this experiment?
To minimise the amount of energy loss to the surroundings
144
Define diffusion
The net movement of particles from an area of higher concentration to an area of lower concentration
145
Diffusion happens in both ______ and ____
Diffusion happens in both liquids and gases
146
Define osmosis
The net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
147
What is a partially permeable membrane?
A membrane with very small holes in it
148
Define active transport
The movement of particles across a semi-permable membrane from an area of lower concentration to an area of higher concentration through the use of energy
149
True or False? All three; diffusion, active transport and osmosis are passive?
False, active transport requires energy
150
Give two differences between the processes of diffusion and active transport
Diffusion is passive whilst active transport requires energy (is active)
Diffusion goes down a concentration gradient, whereas, active transport goes up a concentration gradient
151
When investigating osmosis, what do you put in the sucrose?
Potato cylinders
152
When investigating osmosis, how long do you leave the cylinders in the solution?
For atleast 40 minutes
153
When investigating osmosis, what do you record?
The mass of the potatoes before and after
154
When investigating osmosis, what is the independent variable?
The sucrose solution concentration
155
When investigating osmosis, what is the dependent variable
The mass of potato cylinders lost
156
When investigating osmosis, what are some examples of control variables?
Volume of the sucrose, size of the potato cylinders and type of the potatoes
157
What do we call it when both solutions have the same concentration of water?
Isotonic
158
When investigating osmosis, on the graph what does a positive percentage change in mass represent?
The sucrose solutions concentration is higher than in the cylinders so the chips gain mass as water through osmosis
159
When investigating osmosis, on the graph what does a negative percentage change in mass represent?
The sucrose solutions concentration is lower than in the cylinders so the chips lose mass as water through osmosis
160
When investigating osmosis, on the graph what does no percentage change in mass represent?
That the solutions are isotonic (same water concentration)
161
A group of potato cubes were placed in a sucrose solution and left for one hour
The cube weighed 13.3g at the start and 11.4g at the end
Calculate the percentage change in mass
```
% = (Change / Original) x 100
% = (11.4-13.3 / 13.3) x 100
% = -14.3%
```
162
What is the function of the cell membrane?
Hold the cell together and control what goes in and out
163
Give three structures found in plant cells but not in animal cells
Vacuole
Cell Wall
Chloroplasts
164
Name the subcellular strucutre in plant cells where photosynthesis takes place
Chloroplasts
165
Name two structures that are found in both prokaryotic cells and eukaryotic cells
Ribosomes and cell membrane
166
What does the term haploid mean?
Half the number of chromosomes of that respective organism
167
Give three way in which a human egg cell is adapated to its function
Membrane locks after fertilisation to ensure offspring has correct number of chromosomes
Contains nutrients to nourish early stages of embryo
Haploid nucleus to ensure offspring has correct number of chromosomes
168
What are cilia?
Hair-like structures on the top surface of ciliated epithelial cells
169
Give an advantage of an electron microscope over a light microscope
An electron has a bigger magnification than a light one whilst also having a better resolution
170
Why is it necessary to use thin samples with a light microscope?
The light microscope relies on shining light through the specimen
Therefore, if the specimen is too thick the light won't be able to get through the specimen
171
Write the equation you would use to find the size of a specimen using the magnification used and the size of the image seen through a microscope lens
Image Size / Magnification = Actual Size
172
Describe how you would convert mm to μm?
x 1000
173
What part of an enzyme makes it specific to a particular substrate?
It's active site
174
Why can denatured enzymes no longer catalyse chemical reactions?
Because the substrate will no longer be able to fit into the enzyme
175
Explain how temperature affects enzyme activity
As temperature increases enzyme activity increases until the bonds between the enzyme begin to break further denaturing the enzyme
176
Describe how you could investigate the effect of pH on the rate of amylase activity?
Every 10 seconds add a sample of a solution mixed with a buffer solution with a pH, amylase and starch.
Time how long it takes for the starch to be broken down fully
Repeat with different pH solutions
177
Which two molecules are produced when lipids are broken down?
Fatty and glycerol molecules
178
Name a big molecule that's formed from simple sugars
Starch
179
Describe the colour change that occurs when benedicts reagent is added to a substance containing sugars
Blue -> Green -> Yellow -> Orange -> Red
180
What chemical reagent is used to test for the prescence of starch?
Iodine
181
How would you test for the presence of lipids in a sample?
Shake the substance whilst pouring ethanol until it dissolves then pour the solution into water
Milky water as positive
182
Describe briefly how you could use calorimetry to measure the energy content of a peanut
Add a set volume of water to a test tube
Heat dry food
Calculate temperature change of water
Use equation: E=MxTx4.2
183
If a potato cylinder is placed in a solution with a very high sucrose concentration, what will happen to the mass of the potato cylinder over time?
Explain why?
Mass of potato will decrease
As there will be higher concentration of water in potato than the solution so the water will move down the concentration gradient
