Key Concepts In Biology Flashcards
(177 cards)
1
Q
A
2
Q
What are the two main types of cells?
A
Eukaryotes and Prokaryotes
Eukaryotic cells are complex and include all animal and plant cells, while prokaryotic cells are smaller and simpler, such as bacteria.
3
Q
What is the definition of a prokaryote?
A
A single-celled organism with prokaryotic cells
Prokaryotes are characterized by their lack of a nucleus and simpler structure.
4
Q
List the subcellular structures found in most animal cells.
A
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
- Ribosomes
Subcellular structures are also known as organelles.
5
Q
What is the function of the nucleus in a cell?
A
Contains genetic material that controls the activities of the cell
Genetic material is arranged into chromosomes.
6
Q
What is the role of mitochondria in a cell?
A
Where most of the reactions for respiration take place
Respiration transfers energy that the cell needs to work.
7
Q
What are ribosomes involved in?
A
Translation of genetic material in the synthesis of proteins
Ribosomes are essential for protein production within the cell.
8
Q
What additional structures do plant cells have compared to animal cells?
A
- Rigid cell wall
- Large vacuole
- Chloroplasts
These structures support the cell, maintain internal pressure, and are involved in photosynthesis.
9
Q
What is the function of chloroplasts in plant cells?
A
Where photosynthesis occurs
Chloroplasts contain chlorophyll, which is essential for capturing light energy.
10
Q
What is unique about bacterial cells compared to plant and animal cells?
A
They have no nucleus
Bacterial cells have chromosomal DNA that floats freely in the cytoplasm.
11
Q
What is the structure of chromosomal DNA in bacterial cells?
A
One long circular chromosome
This DNA controls the cell’s activities and replication.
12
Q
What is the purpose of plasmid DNA in bacterial cells?
A
Contain genes for traits like drug resistance
Plasmids can be passed between bacteria, facilitating genetic variation.
13
Q
What is a flagellum?
A
A long, hair-like structure that helps bacteria move
Flagella can help bacteria move towards nutrients or away from toxins.
14
Q
Fill in the blank: All living things are made of _______.
A
cells
Cells are the basic building blocks of all organisms.
15
Q
A
16
Q
What are specialised cells?
A
Cells that are adapted for a particular function.
17
Q
What is the role of egg cells and sperm cells in reproduction?
A
They are specialised for reproduction.
18
Q
What happens during sexual reproduction involving egg and sperm cells?
A
The nucleus of an egg cell fuses with the nucleus of a sperm cell to create a fertilised egg.
19
Q
What type of nucleus do egg cells and sperm cells contain?
A
Haploid nucleus.
20
Q
Why is the haploid nature of egg and sperm cells important?
A
It ensures the resulting fertilised cell has the right number of chromosomes.
21
Q
What does the cytoplasm of an egg cell contain?
A
Nutrients to feed the embryo.
22
Q
What is the primary function of a sperm cell?
A
To transport the male’s DNA to the female’s egg.
23
Q
What adaptation allows sperm cells to swim to the egg?
A
A long tail.
24
Q
What is the role of mitochondria in sperm cells?
A
To provide energy needed for swimming.
25
What is stored in the acrosome of a sperm cell?
Enzymes needed to digest the egg cell membrane.
26
What is the function of ciliated epithelial cells?
To move substances along the surface of tissues.
27
Where are ciliated epithelial cells commonly found?
In the lining of the airways.
28
What do cilia help to move in the airways?
Mucus and trapped particles.
29
Fill in the blank: The nuclei of egg and sperm cells are _______.
haploid.
30
True or False: Both egg and sperm cells contain the full number of chromosomes found in body cells.
False.
31
Name one structural feature of sperm cells that aids in their function.
Long tail.
32
List two functions of ciliated epithelial cells.
* Move substances
* Beat to move mucus in one direction
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What are specialised cells?
Cells that have different structures adapted to their functions.
## Footnote
Examples include muscle cells, nerve cells, and blood cells.
35
What is the role of the nucleus in a cell?
Contains the genetic material and controls the cell's activities.
36
What is the acrosome?
A structure in the head of a sperm cell that contains enzymes to help penetrate the egg cell.
37
What is meant by resolution in microscopy?
The ability of a microscope to distinguish between two points that are close together.
38
True or False: Higher resolution means a clearer and more detailed image.
True.
39
What do light microscopes use to magnify specimens?
Light.
40
What are electron microscopes known for?
Higher magnification and resolution than light microscopes.
## Footnote
They can reveal smaller structures like mitochondria and chloroplasts.
41
Fill in the blank: To view a specimen using a light microscope, your specimen needs to let light through it, so you'll need to take a _______.
thin slice.
42
What is the purpose of adding a drop of stain to a transparent specimen?
To make the specimen easier to see.
43
What is the function of the coarse adjustment knob?
To move the stage up and down for initial focusing.
44
How do you ensure no air bubbles are trapped under the cover slip?
Lower it at an angle and press it down gently.
45
What should you do after selecting the lowest-powered objective lens?
Use the coarse adjustment knob to move the stage up until the slide is just underneath the lens.
46
What does FOV stand for?
Field of View.
47
How do you calculate the new field of view when changing to a higher magnification?
Divide the old FOV by the magnification increase.
48
What features should be included in a scientific drawing of a specimen?
Clear outlines, labels, and the magnification used.
## Footnote
Drawings should not include coloring or shading.
49
What is the importance of keeping all parts in proportion in a scientific drawing?
To accurately represent the specimen.
50
What is the purpose of using a pipette to place a drop of water on a slide?
To secure the specimen in place.
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52
What is the formula for total magnification of an image?
total magnification = eyepiece lens magnification x objective lens magnification
53
If the eyepiece lens magnification is x 10 and the objective lens magnification is x 40, what is the total magnification?
x 400
54
How can you calculate magnification if you don't know which lenses were used?
magnification = image size / real size
55
What should both measurements have in order to use the magnification formula?
the same units
56
What is a useful method for estimating magnification?
Round the numbers to 1 significant figure and perform the division
57
Convert 0.017 into standard form
1.7 x 10^-2
58
What does moving the decimal point to the left represent in standard form?
a positive power of 10
59
What does moving the decimal point to the right represent in standard form?
a negative power of 10
60
How can you express 0.0007 m in different units?
0.7 mm
61
What is the standard form of a millimetre (mm)?
1 mm = 1 x 10^-3 m
62
What is the standard form of a micrometre (um)?
1 um = 1 x 10^-6 m
63
What is the standard form of a nanometre (nm)?
1 nm = 1 x 10^-9 m
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What is the standard form of a picometre (pm)?
1 pm = 1 x 10^-12 m
65
How do you calculate the image size using magnification and real size?
image size = magnification * real size
66
If a specimen is 5 x 10^6 m wide and viewed under a magnification of x 100, what is the width of the image in standard form?
image size = 5 x 10^8 m
67
What is the equivalent of 0.0005 m in millimetres?
0.5 mm
68
How can you input standard form numbers into a scientific calculator?
Using the 'EXP' or 'x 10^' button
69
Calculate the real width of a cheek cell if it is viewed under a microscope with x 40 magnification and the image is 2.4 mm wide.
real width = image width / magnification = 2.4 mm / 40
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71
What is magnification?
The process of enlarging the image of an object
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What does a magnification of x 10 mean?
The image appears 10 times larger than the real size
73
What is the significance of significant figures in measurements?
They indicate the precision of a measurement
74
What is standard form in scientific notation?
A way to express numbers as a product of a number between 1 and 10 and a power of 10
75
What are the units of measurement for tiny objects in standard form?
Examples include 10^-3 m, 10^-9 m, 10^-12 m
76
What role do enzymes play in biological reactions?
They catalyze reactions by lowering the activation energy
77
What is meant by the term 'substrate' in enzyme reactions?
The molecule upon which an enzyme acts
78
What is the active site of an enzyme?
The region where substrate molecules bind and undergo a chemical reaction
79
What happens to an enzyme when the temperature is too high?
The enzyme becomes denatured, altering its shape and function
80
At what temperature do most enzymes exhibit peak activity?
At their optimum temperature, often around 37°C
81
What effect does pH have on enzyme activity?
Extreme pH levels can denature enzymes by disrupting bonds in their structure
82
What is the optimum pH for most enzymes?
Often around pH 7, but can vary; e.g., pepsin works best at pH 2
83
How does substrate concentration affect the rate of enzyme reactions?
Higher substrate concentration typically increases the reaction rate until all active sites are occupied
84
What occurs when all active sites of an enzyme are full?
The reaction rate levels off as adding more substrate does not increase the reaction rate
85
What is the 'lock and key' mechanism in relation to enzymes?
A model explaining how substrates fit perfectly into the active site of an enzyme
86
True or False: Enzymes can function at any temperature.
False
87
Fill in the blank: Enzymes are said to have a high _______ for their substrate.
specificity
88
What is the 'lock and key' model in relation to enzymes?
The substrate ties into the enzyme just like a key fits into a lock.
89
What happens to the rate of an enzyme-catalysed reaction when temperature changes?
Changing the temperature changes the rate of an enzyme-catalysed reaction.
90
What occurs to enzymes at high temperatures?
Some of the bonds holding the enzyme together break, changing the shape of the enzyme's active site.
91
What is meant by an enzyme being 'denatured'?
The enzyme's active site changes shape, preventing the substrate from fitting.
92
What is the optimum temperature for enzymes?
The temperature at which the enzyme is most active.
93
How does pH affect enzymes?
If pH is too high or too low, it interferes with the bonds holding the enzyme together.
94
What is the optimum pH for most enzymes?
Often neutral pH 7, but not always.
95
Give an example of an enzyme with a specific optimum pH.
Pepsin, which works best at pH 2.
96
How does substrate concentration affect the rate of reaction?
Higher substrate concentration increases the reaction rate until all active sites are full.
97
What happens when all active sites of an enzyme are full?
Adding more substrate makes no difference to the reaction rate.
98
Fill in the blank: The rate of reaction shows a steady increase as more _______ molecules are available.
[substrate]
99
True or False: Enzymes function best at temperatures above 100°C.
False.
100
What key terms should be used when discussing enzyme function?
Active site and denatured.
101
Explain why enzymes have an optimum pH.
Enzymes have an optimum pH because it is the pH at which they are most active and stable.
102
What is the enzyme amylase responsible for?
The breakdown of starch to maltose.
103
How can you detect the presence of starch?
Using iodine solution, which changes from browny-orange to blue-black.
104
What is the first step in investigating the effect of pH on amylase activity?
Put a drop of iodine solution into every well of a spotting tile.
105
What temperature should the water be heated to during the experiment?
35 °C.
106
What is the purpose of using a buffer solution in the experiment?
To maintain a constant pH during the reaction.
107
What should you do immediately after adding starch solution to the boiling tube?
Mix the contents and start a stop clock.
108
How often should you sample the contents of the boiling tube?
Every ten seconds.
109
What indicates that starch is no longer present in the experiment?
When the iodine solution remains browny-orange.
110
What should be controlled to ensure a fair test in the experiment?
Variables such as concentration and volume of amylase solution.
111
What is the formula to calculate the rate of reaction?
1000/time.
112
If the time taken for amylase to break down starch at pH 6 is 50 seconds, what is the rate of the reaction?
20 g1.
113
What does the rate of reaction measure?
How much something changes over time.
114
What enzyme catalyses the breakdown of hydrogen peroxide?
Catalase.
115
In an investigation, if 24 cm³ of oxygen was released in 50 seconds, how do you calculate the rate of reaction?
Rate = change/time.
116
Fill in the blank: The enzyme catalase breaks down hydrogen peroxide into ______ and ______.
water; oxygen.
117
True or False: The rate of reaction can be calculated by dividing the amount changed by the time taken.
True.
118
What is the purpose of enzymes in biological processes?
Enzymes facilitate the breakdown of large molecules into smaller components for growth and life processes.
119
What are the big molecules mentioned that need to be broken down?
* Proteins
* Lipids
* Carbohydrates
120
What do lipids consist of?
Fats and oils
121
Why do digestive enzymes break down large molecules?
To convert them into smaller, soluble molecules that can be absorbed into the bloodstream.
122
What do plants store energy as?
Starch
123
What happens to starch when plants need energy?
Enzymes break down the starch into smaller molecules (sugars) for respiration.
124
What type of enzyme converts carbohydrates into simple sugars?
Carbohydrases
125
What is an example of a carbohydrase enzyme?
Amylase
126
What does amylase break down?
Starch into maltose and other sugars
127
What do proteases convert proteins into?
Amino acids
128
What do lipases convert lipids into?
* Glycerol
* Fatty acids
129
What happens to the pH of the solution when lipids are broken down?
The fatty acids lower the pH of the solution.
130
What is the role of enzymes in synthesizing carbohydrates?
Enzymes join together simple sugars to form carbohydrates.
131
What enzyme synthesizes glycogen from glucose?
Glycogen synthase
132
How are proteins synthesized?
By joining amino acids together
133
What is the role of enzymes in lipid synthesis?
They are involved in synthesizing lipids from fatty acids and glycerol.
134
Fill in the blank: Enzymes called ________ convert carbohydrates into simple sugars.
carbohydrases
135
True or False: Enzymes are only involved in the breakdown of molecules.
False
136
What do proteases convert proteins into?
Amino acids
## Footnote
Proteases are enzymes that catalyze the breakdown of proteins.
137
What do lipases convert lipids into?
Glycerol and fatty acids
## Footnote
Lipases are enzymes that facilitate the breakdown of lipids.
138
What effect do fatty acids have on the pH of a solution?
Lower the pH
## Footnote
This occurs when lipids are broken down.
139
What is the role of enzymes in the synthesis of carbohydrates?
Join together simple sugars
## Footnote
Enzymes catalyze the reactions needed for carbohydrate synthesis.
140
What enzyme is responsible for synthesizing glycogen from glucose?
Glycogen synthase
## Footnote
Glycogen is a molecule used to store energy in animals.
141
What are the smaller components that make up carbohydrates, proteins, and lipids?
Simple sugars, amino acids, fatty acids, and glycerol
## Footnote
Understanding these components is essential for studying biomolecules.
142
Fill in the blank: Enzymes are used in the process of _______ carbohydrates, proteins, and lipids from their smaller components.
Synthesizing
## Footnote
Enzymes catalyze both the breakdown and synthesis of larger biomolecules.
143
True or False: Enzymes only play a role in the breakdown of larger biomolecules.
False
## Footnote
Enzymes are involved in both the breakdown and synthesis of larger biomolecules.
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146
What is diffusion?
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
## Footnote
It is the natural tendency for substances to spread out.
147
In which states of matter does diffusion occur?
Diffusion occurs in both liquids and gases.
## Footnote
Particles in these substances are free to move about randomly.
148
What types of molecules can diffuse through cell membranes?
Only very small molecules such as glucose, amino acids, water, and oxygen can diffuse through cell membranes.
## Footnote
Big molecules like starch and proteins cannot fit through the membrane.
149
What is osmosis?
Osmosis is 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.
## Footnote
It can also be described as movement from lower solute concentration to higher solute concentration.
150
What is a partially permeable membrane?
A partially permeable membrane is one with very small holes that allow tiny molecules (like water) to pass through, but not bigger molecules (e.g., sucrose).
## Footnote
This selective permeability is crucial for osmosis.
151
During osmosis, how do water molecules move?
Water molecules move both ways through the membrane, but there is a net flow of water into the region with fewer water molecules.
## Footnote
This is due to the higher concentration of water on one side.
152
What happens to the solute solution as water moves in during osmosis?
The solute solution gets more dilute as water moves in.
## Footnote
The water is trying to 'even up' the concentration on either side of the membrane.
153
What is active transport?
Active transport is the movement of particles across a membrane against a concentration gradient.
## Footnote
It involves moving substances from an area of lower concentration to an area of higher concentration.
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155
What is the net movement of water molecules across a membrane called?
Osmosis
## Footnote
Osmosis is the movement of water into the region with fewer water molecules.
156
What happens to the solute solution during osmosis?
It becomes more dilute
## Footnote
The water acts like it's trying to even up the concentration either side of the membrane.
157
What is active transport?
The movement of particles across a membrane against a concentration gradient using energy
## Footnote
Active transport moves particles from an area of lower concentration to an area of higher concentration.
158
How does active transport differ from diffusion?
Active transport requires energy and moves particles up a concentration gradient
## Footnote
Diffusion is a passive process that moves particles down a concentration gradient.
159
Provide an example of active transport in the digestive system.
Nutrients are taken into the blood from the gut against the concentration gradient
## Footnote
This occurs when there is a lower concentration of nutrients in the gut than in the blood.
160
True or False: Active transport is a passive process.
False
## Footnote
Active transport requires energy, while passive processes do not.
161
Fill in the blank: A sodium ion moves from inside a nerve cell to outside the cell where the concentration is higher. This movement is called _______.
Active transport
## Footnote
The sodium ion is moving against the concentration gradient.
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What is the purpose of the experiment described?
To investigate the effect of different sucrose concentrations on the mass of potato cylinders.
164
What is the relationship between sucrose concentration and water concentration?
The higher the concentration of the sucrose solution, the lower the water concentration.
165
What should the diameter of the potato pieces be for the experiment?
About 1 cm in diameter.
166
What is the concentration of pure water in molarity (M)?
0.0 M.
167
What is the first step in preparing for the osmosis experiment?
Prepare sucrose solutions of different concentrations.
168
How long should the potato cylinders be left in the sucrose solution?
At least 40 minutes.
169
What is the purpose of patting the potato cylinders dry?
To remove excess water for a more accurate measurement of their final masses.
170
What must remain constant in the experiment to ensure valid results?
Everything else, such as volume of solution, size of potato cylinders, type of potatoes, and amount of drying.
171
What unit of concentration is used in the experiment?
M (mol dm⁻³).
172
Fill in the blank: The only variable that should change in the experiment is the _______.
sucrose solution concentration.
173
What is the final step after removing the potato cylinders from the solution?
Weigh each group again and record your results.
174
True or False: All potato pieces should be cut from different potatoes.
False.
175
What do you need to calculate after conducting the experiment?
The percentage change in mass for each potato cylinder.
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