SB1: Key Concepts In Biology Flashcards
1
Q
What are prokaryotic cells?
A
Small, simple cells without a nucleus
2
Q
What are prokaryotes?
A
Single-celled prokaryotic organisms
3
Q
What are eukaryotic cells?
A
Complex cells that contain nucleus and other sub cellular structures
4
Q
What is the role of the nucleus?
A
Controls activities of the cell
5
Q
Name the sub cellular structure where respiration takes place
A
Mitochondria
6
Q
Which stage of protein synthesis are ribosomes involved in?
A
Second stage (translation)
7
Q
What is the function of the cell wall?
A
A rigid structure that supports and strengthens plant cells
8
Q
What is cell sap made from?
A
Weak solution of sugar and salts dissolved in water
9
Q
What is the function of the solution contained inside the vacuole?
A
To maintain internal pressure of a cell, to provide support
10
Q
What is the function of the chlorophyll contained inside chloroplasts?
A
To absorb light energy needed for photosynthesis
11
Q
Name the parts of a bacterial cell
A
~ cytoplasm ~ cell membrane ~ cell wall ~ singular circular strand of chromosomal DNA ~ plasmid DNA ~ flagellum ~ ribosomes
12
Q
Name the part of a bacterial cell that controls the cells replication
A
Singular circular strand of chromosomal DNA
13
Q
Name the small loops of DNA found in many bacterial cells
A
Plasmids
14
Q
What type of information is contained within the plasmids?
A
Drug resistance
15
Q
Describe what a flagellum is
A
Long hair-like structures
16
Q
Give two reasons why bacterial cells find it beneficial to have a flagellum
A
(1) move towards areas of beneficial condition eg. Those high in nutrients and oxygen
(2) can move away from areas of harmful conditions eg. Chemicals, heat
17
Q
Explain why multicellular organisms contain many different types of cells
A
Each individual cell cannot carry out every life process so cells become specialised to do different jobs
18
Q
What word is used to describe these different types of cells?
A
Specialised
19
Q
What is the structure of each type of cell related to?
A
It’s specific function
20
Q
Name the four types of animal cells that you need to know how their structure s linked to their specific function
A
~ egg cell
~ sperm cell
~ small intestine cell
~ ciliated epithelial cell
21
Q
Name five adaptations of a sperm cell
A
~ long tail ~ streamlined shape ~ mitochondria concentrated area at base of tail ~ acrosome ~ haploid nucleus of male DNA
22
Q
Name the adaptation that propels a sperm cell forward
A
The tail
23
Q
Name the adaptation that provides the energy for the tail
A
Mitochondria concentrated area at base of tail
24
Q
Name the adaptation that makes it easier for a sperm cell to move
A
Streamlined shape
25
Name the part of the sperm cell that contains enzymes
Acrosome
26
What is the function of the enzymes found in the acrosome?
To digest the cell membrane of the egg
27
Where is the acrosome found?
In the front tip of the head
28
What is the function of a sperm cell?
To transport male DNA to female DNA found in the egg
29
Name three adaptations of the egg cell
~ high nutrient content
~ haploid nucleus
~ cell membrane can change structure
30
Name one adaptation that both sperm cells and egg cells share?
Haploid nucleus
31
Explain why both sperm and egg cells have a haploid nucleus?
So the zygote has correct number of chromosomes (46)
32
What adaptation happens straight after fertilisation (in egg cell)?
The cell membrane changes structure
33
Explain why egg cells are very large cells
They contain a large amount of nutrients in the cytoplasm to provide nourishment to developing embryo
34
Name two functions of an egg cell
(1) to carry the female DNA
| (2) to nourish developing embryo
35
Name two adaptations of an egg cell that ensure a resulting embryo has the correct number of chromosomes
(1) haploid nucleus
| (2) membrane that changes structure after one sperm has entered
36
Which cell is found in the airways?
Ciliated (epithelial) cells
37
What is the main adaptation of a ciliated (epithelial) cell?
Hair-like structures on the top surface of the cell
38
What is the function of the hair-like structures on a ciliated (epithelial) cell?
To move substances in one direction along the surface of the tissue
39
Explain why ciliated (epithelial) cells contain a high number of mitochondria
To provide enough energy to move the cilia
40
Where in a female body are ciliated (epithelial) cells found?
Fallopian tubes/oviduct
41
What is the role of specialised cells found in the small intestine?
To absorb molecules through intestinal wall
42
Name the sub cellular structures that increase the rate that small intestine cells absorb molecules through the intestinal walls
Microvilli
43
Explain how the microvilli in small intestine cells are adapted to their function
They increase the surface area of the cell
44
When was the first microscope (light microscope) developed?
1590s
45
What can we see using a microscope?
Individual cells and large sub cellular structures
46
What is the maximum magnification of a light microscope?
x 1500
47
What is the maximum resolution (in mm) of a light microscope?
0.0001mm
48
How would you write 0.0001mm in standard form?
1 x 10^-4m
49
How would you write 0.0001mm in nanometres?
100nm
50
How do light microscopes form an image?
Using light and lenses
51
Write one picometre in standard form
1 x 10^-12m
52
Write one nanometre in standard form
1 x 10^-9m
53
Write 6 micrometres in standard form
6 x 10^-6m
54
Convert 6mm into nanometres
6,000,000nm or 6 x 10^6nm
55
When was the electron microscope developed?
1930s
56
How does the electron microscope form an image?
Uses beams of electrons passing through a specimen
57
What is the maximum resolution (in mm) of an electron microscope?
0.0000002mm
58
What is the maximum magnification of an electron microscope?
x 2,000,000
59
Explain why electron microscopes show more detail than light microscopes
Greater magnification and greater resolution
60
When preparing a slide, what is first placed on a clean slide?
Drop of water
61
Explain the function of putting a drop of water on a slide
To secure the specimen in place
62
What stain would you use when preparing a slide of onion skin?
Iodine
63
What stain would you use when preparing a slide of cheek cells?
Methyl blue
64
Which objective lens should be chosen first?
Lowest magnification
65
What part of the microscope would you use first to move the stage?
Coarse adjustment knob
66
Where should the stage be placed before looking down the eyepiece?
Just below objective lens
67
Which part of the microscope should be used to bring the image roughly into focus?
Coarse adjustment knob
68
What direction should the coarse adjustment knob be moved in to bring the image roughly into focus?
Downwards
69
What should be moved to bring the image into clear focus?
Fine adjustment knob
70
What should you do if you want to see the image at a higher magnification?
Swap to higher powered objective lens and refocus
71
Compare today’s light microscope with Hooke’s
Modern light microscope: contains barrel with two lenses, uses light, magnification up to x1500, resolution down to 0.0001mm
Hooke’s microscope: contains barrel with two lenses, uses light, magnification up to x30, resolution down to 0.002mm
72
What do enzymes act as?
Biological catalysts
73
What type of molecule are enzymes?
Proteins
74
What gives each type of enzyme a unique shape?
The way the chain of amino acids folds up
75
What are the molecules that interact with the enzyme called?
Substrate
76
What is the uniquely shaped section of an enzyme called?
The active site
77
What happens at the active site?
The substate fits into the active site
78
What does ‘high specificity’ for a substrate mean?
The enzyme will only interact with the specific substrate that matches the shape of it’s active site
79
Explain why increasing temperature will usually increase the rate of an enzyme-catalysed reaction
The reactants have more energy, so they move around more and collide more often with enough energy for a reaction to take place
80
Explain why enzymes will stop working if they get too hot
Some bonds holding the protein structure of the enzyme in place will break and change the shape of the enzyme. If the shape of the active site is changed it will stop working because the substrate will no longer fit into the active site
81
What temperature do human enzymes work at?
37-38˚C
82
At what temperatures do most human enzymes stop working?
45˚C
83
Explain why the higher the concentration of a substrate, the quicker the reaction
The higher the concentration, the more likely that the enzyme will collide with and interact with the substrate molecule
84
When does the concentration of a substrate no longer affect the rate of reaction?
When the number of substrate molecules is greater than the number of enzyme active sites/when all enzyme active sites are full
85
How does pH affect an enzyme if it is too high or too low??
pH affects bonds holding enzymes together therefore changing their shape and active site. The enzyme becomes denatured.
86
When investigating the effect of pH on the action of the enzyme amylase, what equipment would you need?
```
~ spotting tile
~ dropping pipette
~ iodine solution
~ (Bunsen burner, tripod, gauze, heatproof mat) or (water bath)
~ 250ml beaker
~ boiling tube
~ 5ml syringes
~ test tube holder
~ stopwatch
```
87
What chemicals are used when investigating the effect of pH on the action of the enzyme amylase?
~ iodine solution
~ pH buffers - pH 1 - pH 12
~ starch solution
~ amylase solution
88
Why is it important to repeat the investigation of the effect of pH on the action of the enzyme amylase three times?
To produce a more accurate average time after removing outliers
89
Name the independent variable when investigating the effect of pH on the action of the enzyme amylase
The pH of buffer solutions
90
Name the dependent variable when investigating the effect of pH on the action of the enzyme amylase
The time taken for starch to be digested/ iodine solution to stay brown
91
State the control variables when investigating the effect of pH on the action of the enzyme amylase
~ the same temperature of water in beaker/water bath
~ same volume of amylase solution, pH buffer and starch solution
~ same concentration of amylase solution, starch solution and iodine solution
92
State the equation to calculate the rate of reaction of the enzymes when investigating the effect of pH on the action of the enzyme amylase
Rate of reaction = 1000 / time
93
At pH6, it takes amylase 90 seconds to digest a starch solution. Calculate the rate of reaction
1000 / 90 = 11s^-1
94
State the equation used to calculate the rate of reaction of an enzyme
Rate of reaction = change / time
95
An enzyme produces 24cm^3 of a gas over 50 seconds. Calculate the rate of reaction
24 / 50 = 0.48cm^3
96
What is the function of a pH buffer?
To maintain constant pH throughout the reaction, therefore maintain constant conditions in the boiling tube
97
Name three main groups of big biological molecules that are essential for life
Carbohydrates, proteins, lipids
98
What do organisms need to do to use carbohydrates, proteins and lipids for life processes such as growth?
Break them down into their smaller components
99
Name the type of enzyme that digests carbohydrates
Carbohydrases
100
Name the type of enzyme that digests carbohydrates found in saliva
Amylase
101
What big molecule is digested by amylase?
Starch
102
What is starch broken down into?
Maltose and other simple sugars e.g. glucose
103
Describe the molecules produced by digestion
Small and soluble
104
Name the type of enzyme that digests proteins
Proteases
105
Where are proteases found in the body?
In the stomach/ gastric juices
106
What are proteins broken down into when they are digested?
Amino acids
107
What are lipids broken down into by lipase?
Three fatty acids and one glycerol
108
Where are lipase and carbohydrase found together in the body?
Intestines
109
In addition to breaking down molecules, name another function of enzymes in the body
Synthesis of new molecules
110
Name the two groups of sugars that can be tested for
~ reducing sugars (eg. Glucose)
| ~ non-reducing sugars (eg. Sucrose)
111
Describe how you would prepare a solid food sample for testing its content of sugars, starch and proteins (4 marks)
1. Break up food in a pestle and mortar
2. Transfer the ground up food into a beaker and add some distilled water
3. Stir the mixture vigorously
4. Let mixture to settle and pipette out some of the liquid to use as the sample
112
Name the test for reducing sugars
Benedict’s test
113
What is a positive result for reducing sugars?
Solution changes from normal blue colour to green, yellow to red. The higher the concentration of reducing sugar, the further the colour change goes
114
Explain why the water bath is set at 75˚C for the Benedict’s test for reducing sugars
To speed up the rate of reaction and therefore any colour change
115
Explain why each food sample should be heated for the same amount of time in the Benedict’s test for reducing sugars?
So the results can be compared - to make it a fair test
116
Name the test for starch
Iodine solution
117
Describe a positive result for the food test for starch
Solution turns blue/black colour
118
What colour is a negative result for the iodine solution test for starch?
Yellow/brown colour
119
Name the test for proteins
Biuret test
120
Name two chemicals used to test food for protein
Potassium hydroxide and copper (II) sulfate solution
121
Describe a positive result for protein in food
Changes from blue to purple/lilac/pink
122
Describe a negative result for protein in food
Remains blue
123
Name the test for lipids
Emulsion test
124
How do you prepare a sample of solid food to be tested for lipids?
Grind it up in a pestle and mortar
125
What substance is added to the food sample in a test tube?
Ethanol
126
After shaking, what is added to the food sample in a test tube after ethanol?
Distilled water
127
Describe a positive result for the Emulsion test for lipids
Precipitate is seen as a milky emulsion
128
Name the type of experiments that can be used to work out the energy in different foods
Calorimetry
129
Some foods were burnt to find out how much energy they contained. Explain how this experiment shows how much energy a food contains (2 marks)
The higher the temperature rise of the water, the more energy is contained within the food
130
State the equation to calculate the total amount of energy in the burned food
Energy in food (J) = mass of water (g) x temperature change of water (˚C) x 4.2
131
Explain why it is important to calculate the energy per gram of food when burning it to test the energy
To be able to compare the results of each food - food samples are not exactly the same mass
132
Explain why results from burning foods to find their energy is only an estimation
Energy is lost to the surroundings and the test tube instead of being transferred to the water
133
How do substances pass into and out of cells?
Diffusion, osmosis and active transport
134
How do smells spread?
Diffusion
135
Cells have partially permeable membranes. What does this mean?
The membranes only let some molecules through but not others
136
What type of molecules can move through partially permeable membranes?
Very small molecules
137
Describe the movement of particles in fluids
Random
138
Give a definition of osmosis
The net movement of water molecules across a partially permeable membrane from an area of higher water concentration to an area of lower water concentration
139
State the net movement of water molecules across a partially permeable membrane separating distilled water on one side and sucrose solution on the other side
From distilled water into the sucrose solution
140
If a cell is short of water what happens to the concentration of the solution inside?
It becomes more concentrated
141
What happens to animal cells that gain too much water?
They burst
142
What happens to plant cells that gain too much water?
They become turgid (swollen)
143
State the name for the process where particles can move against a concentration gradient
Active transport
144
Explain how cells can absorb ions from dilute solutions
Energy transferred from respiration is used to move ions from an area of lower concentration to an area of higher concentration/ against a concentration gradient
145
Name a plant cell that relies on active transport to absorb minerals
Root hair cell
146
Name an animal cell that relies on active transport to absorb glucose
Small intestine epithelial cell
147
Using three different concentrations of sucrose solution, describe how you could investigate their effect on parsnip cells (6 marks)
1. Use a cork borer to cut a parsnip into the same sized pieces eg. 1cm x 2cm cylinders
2. Divide the cylinders into groups of three and use a balance to measure the mass of each group
3. Place 100cm^3 of each sucrose solution into separate beakers, and place a group of cylinders into each solution
4. Leave the cylinders in the solutions for one hour
5. Remove the cylinders and gently pat dry with paper towels
6. Use the balance to measure the new mass of each group
148
Name the dependent variable when testing the effect on parsnip cells in three different concentrations of sucrose solution
The cylinder mass
149
Name the control variables when testing the effect on parsnip cells in three different concentrations of sucrose solution
```
~ same volume of solution
~ amount cylinders are dried
~ size of cylinders
~ age + type of parsnips
~ time cylinders are left in sugar solutions
```
150
State the equation to calculate percentage change in mass when testing the effect on parsnip cells in three different concentrations of sucrose solution
((Final mass - initial mass) / initial mass) x 100
151
A group of cylinders weighed 14.3g at the start of an osmosis experiment and 17.4g at the end. Calculate the percentage change in mass
((Final mass - initial mass) / initial mass) x 100
| ((17.4 - 14.3) / 14.3) x 100 = 21.7%
152
How do you find the concentration of a parsnip cell after plotting the percentage change in mass against the concentration of sucrose solution in an osmosis experiment? (2 marks)
1. Draw line of best
| 2. Find point at which the line of best fit crosses the x-axis
153
Describe an adaptation of a fat cell
Large amount of fat stored in droplets in the cell
154
Explain how red blood cells are specially adapted to carry oxygen around the body
No nucleus makes more room for haemoglobin which combines with oxygen
155
Describe the special feature of muscle cells that allow them to contract
Contains proteins that contract to shorten the cell
156
Describe how the cells that line the gut are specialised to absorb nutrients
~ microvilli increase their surface area
| ~ contain mitochondria to provide energy for active transport
157
Explain how nerve cells are adapted to their function
~ long fibre that carries electrical impulses around the body
~ many short connections to link to other nerve cells
~ myelin sheath to insulate impulse as it travels along the axon
