Biology Section 1 Flashcards
1
Q
What is the main function of palisade mesophyll cells?
A
To capture energy transferred by light
2
Q
Describe the shape of palisade cells.
A
Cylindrical shaped
3
Q
Where are palisade mesophyll cells located?
A
In the upper part of a leaf
4
Q
What do palisade cells contain to aid photosynthesis?
A
Many chloroplasts
5
Q
What role does the large vacuole play in palisade cells?
A
Helps to keep the cell and leaf structure rigid
6
Q
Where are root hair cells found?
A
In the epithelium near the root tip
7
Q
What is the function of root hair cells?
A
To absorb water and dissolved minerals from the soil
8
Q
How do root hair cells increase their efficiency in absorbing water?
A
They have a large surface area to volume ratio
9
Q
What type of wall do root hair cells have?
A
Thin cell wall
10
Q
Why do root hair cells contain many mitochondria?
A
To help supply energy for active transport of minerals
11
Q
Fill in the blank: Palisade cells are found in leaf tissue and mainly function to _______.
A
[capture energy transferred by light]
12
Q
True or False: Root hair cells have a thick cell wall to aid in water absorption.
A
False
13
Q
What are mammalian gametes?
A
Sperm and egg
Gametes are specialized cells involved in reproduction.
14
Q
What is the function of the undulipodium in sperm?
A
Movement to swim to the egg
15
Q
What type of nucleus does a sperm cell have?
A
Haploid nucleus containing one set of chromosomes
16
Q
What happens when the sperm nucleus fuses with the egg cell nucleus?
A
Full number of chromosomes is restored at fertilisation
17
Q
What is the role of cortical granules in an egg cell?
A
Contain substances that prevent more than one sperm fertilising the egg
18
Q
What provides energy for movement in an egg cell?
A
Mitochondria in the mid region
19
Q
What is the function of the acrosome in sperm?
A
Contains enzymes to digest the outer layers of the egg
20
Q
What is the zona pellucida?
A
Jelly layer that stops more than one sperm fertilising the egg
21
Q
What is the primary function of white blood cells?
A
Fight pathogens
22
Q
Where are white blood cells made?
A
Bone marrow and lymph nodes
23
Q
What are the two types of white blood cells mentioned?
A
Phagocytes and lymphocytes
24
Q
What is the shape of red blood cells?
A
Biconcave discs
25
Do mature red blood cells have a nucleus?
No
26
What is contained in the cytoplasm of red blood cells?
Haemoglobin
27
Why do red blood cells lack a nucleus?
To allow more room for haemoglobin
28
What structural feature of red blood cells optimizes their surface area?
Biconcave shape
29
Fill in the blank: Phagocytes and _______ are types of white blood cell.
Lymphocytes
30
True or False: Red blood cells can divide.
False
31
What allows red blood cells to squeeze through narrow blood vessels?
Their size and shape
32
Describe three structural differences between a human sperm cell and a human egg cell.
1. Sperm has a tail (undulipodium), egg does not
2. Sperm has a haploid nucleus, egg has a larger cytoplasm
3. Egg has cortical granules, sperm has acrosome
33
What are mammalian gametes?
Sperm and egg
## Footnote
Gametes are specialized cells involved in reproduction.
34
What is the function of the undulipodium in sperm?
Movement to swim to the egg
35
What type of nucleus does a sperm cell have?
Haploid nucleus containing one set of chromosomes
36
What happens when the sperm nucleus fuses with the egg cell nucleus?
Full number of chromosomes is restored at fertilisation
37
What is the role of cortical granules in an egg cell?
Contain substances that prevent more than one sperm fertilising the egg
38
What provides energy for movement in an egg cell?
Mitochondria in the mid region
39
What is the function of the acrosome in sperm?
Contains enzymes to digest the outer layers of the egg
40
What is the zona pellucida?
Jelly layer that stops more than one sperm fertilising the egg
41
What is the primary function of white blood cells?
Fight pathogens
42
Where are white blood cells made?
Bone marrow and lymph nodes
43
What are the two types of white blood cells mentioned?
Phagocytes and lymphocytes
44
What is the shape of red blood cells?
Biconcave discs
45
Do mature red blood cells have a nucleus?
No
46
What is contained in the cytoplasm of red blood cells?
Haemoglobin
47
Why do red blood cells lack a nucleus?
To allow more room for haemoglobin
48
What structural feature of red blood cells optimizes their surface area?
Biconcave shape
49
Fill in the blank: Phagocytes and _______ are types of white blood cell.
Lymphocytes
50
True or False: Red blood cells can divide.
False
51
What allows red blood cells to squeeze through narrow blood vessels?
Their size and shape
52
Describe three structural differences between a human sperm cell and a human egg cell.
1. Sperm has a tail (undulipodium), egg does not
2. Sperm has a haploid nucleus, egg has a larger cytoplasm
3. Egg has cortical granules, sperm has acrosome
53
What type of tissue lines surfaces in contact with the external environment?
Epithelial tissue
## Footnote
Epithelial cells also line internal organs such as the lungs.
54
What are the two types of epithelial tissue found in the lungs?
* Squamous epithelium
* Columnar epithelium
55
What type of epithelial cells line the upper airway (trachea and bronchi)?
Ciliated columnar epithelium cells
## Footnote
These cells are rich in mitochondria.
56
What is the function of cilia on epithelial cells in the lungs?
Move mucus away from the lungs
57
What type of cells produce mucus in the respiratory system?
Goblet cells
58
What is the role of the mucus layer in the airways?
Trap unwanted particles present in the air
59
Describe the structure of squamous epithelium.
Very flat and thin with egg-shaped nuclei, often only one cell thick
60
Why is squamous epithelium particularly suited for the lungs?
It is very good for surfaces where diffusion occurs.
61
What is Chronic Obstructive Pulmonary Disease (COPD)?
A condition that includes several diseases more common in smokers
62
How does cigarette smoke affect ciliated columnar epithelium in the lungs?
Slows and stops cilia beating, leading to mucus buildup
63
What happens to the alveolar epithelial cells due to mucus buildup from smoking?
They can rupture, reducing the surface area for gas exchange
64
What is a consequence of reduced surface area for gas exchange in the lungs?
It provides a good environment for pathogens to grow
65
Fill in the blank: Cilia are tiny hairs on the outer surface of epithelial cells that ______.
waft back and forth to move surface mucus out of lungs
66
Explain why ciliated columnar cells contain many mitochondria.
To provide energy for the movement of cilia
67
What lines the inside of blood vessels?
Endothelial tissue
## Footnote
Endothelial tissue is made up of a single layer of flat, long cells oriented lengthways in the direction of blood flow.
68
What is the function of endothelial tissue in blood vessels?
To provide a smooth surface for easy blood flow
## Footnote
This smooth surface minimizes friction as blood flows over it.
69
What are the three types of blood vessels?
* Artery
* Vein
* Capillary
## Footnote
Arteries and veins have similar structures but differ in proportions of tissue.
70
What tissue type is thicker in veins and why?
Connective and elastic tissue to prevent collapse
## Footnote
This thicker outer layer helps veins maintain their shape under varying blood pressure.
71
What is thicker in arteries compared to veins?
Middle layer of smooth muscle, connective and elastic tissue
## Footnote
This thickness is necessary to maintain higher blood pressure in arteries.
72
What is atherosclerosis?
A disease process leading to coronary disease and strokes
## Footnote
Atherosclerosis involves the buildup of fatty deposits in arteries.
73
What can cause blood clots to form in an artery?
Damage to tissue and formation of clots
## Footnote
Such clots can lead to serious health problems, including heart attacks and strokes.
74
What are fatty deposits in arteries called?
Atheroma
## Footnote
Atheroma can block arteries directly or increase the risk of thrombosis.
75
What are the steps in the development of atherosclerosis?
* Damage to endothelial tissue
* Accumulation of LDL cholesterol
* Inflammation and white blood cell movement
* Narrowing of artery and loss of elasticity
## Footnote
These steps restrict blood flow and increase the risk of clotting.
76
What effect does cigarette smoke have on the blood?
Increases thickness of blood
## Footnote
This thickening leads to fatty deposits on artery walls, increasing clotting risk.
77
True or False: Smoking decreases blood pressure and heart rate.
False
## Footnote
Smoking actually increases both blood pressure and heart rate, contributing to endothelial damage.
78
Fill in the blank: Atherosclerosis can lead to _______ and strokes.
Coronary disease
## Footnote
These cardiovascular diseases are serious and often life-threatening.
79
What are the two types of muscle fibers?
Slow twitch and fast twitch
## Footnote
Slow twitch fibers are suited for endurance, while fast twitch fibers are suited for high-intensity, short-duration activities.
80
What is the basic unit needed for muscle contraction?
Sarcomere
## Footnote
Sarcomeres are repeated units of actin and myosin filaments.
81
What are muscle fibers made up of?
Bundles of cells called muscle fibers
## Footnote
These fibers are composed of myofibrils, which contain actin and myosin filaments.
82
What happens to the sarcomere during muscle contraction?
Shortening of the sarcomere
## Footnote
This occurs as thin actin filaments move between thick myosin filaments.
83
Fill in the blank: Slow twitch muscle fibers are characterized by _______.
sustained contractions
## Footnote
These fibers are used for long-duration activities and do not tire easily.
84
Fill in the blank: Fast twitch muscle fibers are characterized by _______.
rapid contractions
## Footnote
These fibers are suited for short bursts of intense activity.
85
True or False: Fast twitch muscle fibers have many mitochondria.
False
## Footnote
Fast twitch fibers have few mitochondria and primarily rely on anaerobic respiration.
86
What type of respiration do slow twitch muscle fibers use?
Aerobic respiration
## Footnote
This type of respiration requires oxygen and is used for endurance activities.
87
What type of respiration do fast twitch muscle fibers use?
Anaerobic respiration
## Footnote
This type of respiration does not require oxygen and is suited for short bursts of activity.
88
Which type of muscle fiber is advantageous for marathon runners?
Slow twitch fibers
## Footnote
These fibers allow for endurance and longer periods of activity without fatigue.
89
What is the primary energy source for fast twitch muscle fibers?
Glucose from anaerobic respiration
## Footnote
Fast twitch fibers primarily use glucose for quick bursts of energy.
90
How do the proportions of slow and fast twitch muscles affect athletic performance?
Higher fast twitch proportions favor sprinting; higher slow twitch proportions favor endurance events
## Footnote
Athletes may have different muscle fiber compositions that suit their sports.
91
What are nerves made up of?
Cells called neurones
## Footnote
Neurones carry messages in the form of electric signals.
92
What do neurones carry?
Messages in the form of electric signals
## Footnote
These messages are also known as nerve impulses.
93
What are the two main divisions of the nervous system in mammals?
Central nervous system (CNS) and peripheral nervous system
## Footnote
The CNS includes the brain and spinal cord.
94
What is the function of the axon in a neurone?
Conduct nervous impulses
## Footnote
The axon is adapted for this role.
95
What is the role of the cell body in a neurone?
Contains the nucleus and produces materials needed by the cell
## Footnote
The nucleus is a key component of the cell body.
96
What is an action potential?
An electric impulse
## Footnote
It travels along the axon of a neurone.
97
What is the myelin sheath?
An electrically insulating layer around the axon
## Footnote
It helps speed up the transmission of impulses.
98
What are the gaps in the myelin sheath called?
Nodes of Ranvier
## Footnote
They allow the electrical impulse to pick up speed.
99
What is the difference between myelinated and non-myelinated nerve cells?
Non-myelinated do not have a myelin sheath; myelinated do have a myelin sheath
## Footnote
This affects the speed of impulse transmission.
100
What type of neurone connects sensory receptors to the central nervous system?
Sensory neurone
## Footnote
It plays a crucial role in sensory perception.
101
Where are motor neurones found?
In the central nervous system
## Footnote
They communicate from the CNS to effectors.
102
What does 'progressive' mean in the context of multiple sclerosis?
Increases over time
## Footnote
This refers to the worsening of the disease symptoms.
103
What does 'de' before a word generally signify?
Removal of
## Footnote
In multiple sclerosis, it refers to the removal of the myelin sheath.
104
What is multiple sclerosis known as?
'Progressive de-myelinating disease'
## Footnote
It affects the nervous system.
105
Fill in the blank: Nerve cells that transmit pain and temperature changes are usually _______.
Non-myelinated
## Footnote
These cells are typically smaller in diameter.
106
True or False: Myelinated nerve cells transmit impulses slower than non-myelinated cells.
False
## Footnote
Myelinated nerve cells transmit impulses very fast.
107
What is the term for the electrical signal transmitted between nerve cells?
Action potential
## Footnote
An action potential is triggered by changes in the polarity of the nerve cell.
108
What is the threshold potential?
The minimum potential difference required to trigger an action potential
## Footnote
If the threshold potential is not reached, no action potential occurs.
109
What happens during depolarization?
Na+ gates open, Na+ diffuses into the cell
## Footnote
This causes the inside of the nerve cell to become more positive.
110
What is repolarization in nerve cells?
K+ gates open, K+ diffuses out of the cell
## Footnote
This helps restore the negative charge inside the cell.
111
What is the typical resting potential of a nerve cell?
Between -60 and -70 mV
## Footnote
The resting potential varies depending on the type of nerve cell.
112
What is saltatory conduction?
The process where nerve impulses jump from one node of Ranvier to the next
## Footnote
This occurs in myelinated nerve fibers and increases conduction speed.
113
Fill in the blank: The action potential cannot be generated in a _______ section of the nerve for about 5 milliseconds.
Refractory
## Footnote
This ensures that the impulse travels in one direction.
114
True or False: The only region of a myelinated nerve fiber that can depolarize is at the nodes of Ranvier.
True
## Footnote
This allows for faster transmission of nerve impulses.
115
What happens to the ion channels during the action potential?
Na+ channels open, K+ channels open and then close
## Footnote
This sequence of events is crucial for the propagation of the action potential.
116
Describe the role of K+ ions during the repolarization phase.
K+ ions diffuse out of the cell, restoring negative charge
## Footnote
This process is essential for returning the cell to its resting state.
117
What is the significance of the action potential reaching +40 mV?
It indicates the peak of depolarization
## Footnote
This is the maximum positive charge achieved before repolarization begins.
118
What causes the hyperpolarization of the nerve cell?
K+ diffuses out, making the inside more negative than resting potential
## Footnote
Hyperpolarization occurs when the membrane potential drops below -70 mV.
119
What are the two forces causing ions to move at a specific point in the action potential?
Concentration gradient and electrical gradient
## Footnote
These forces influence the direction and flow of ions during the action potential.
120
What does an electrocardiogram (ECG) measure?
The action potentials of the heart
## Footnote
ECG measures electrical impulses by placing electrodes on the body.
121
How is an ECG trace created?
By detecting electrical impulses and amplifying them during each heartbeat
## Footnote
A machine records these impulses to show the heart's electrical changes.
122
What is the normal heart rate represented in an ECG pattern?
60 to 100 beats per minute at regular intervals
## Footnote
Disruptions in this pattern can indicate cardiovascular disease.
123
What does the QRS complex represent in an ECG?
The time of ventricular systole (contraction)
## Footnote
It shows the electrical activity associated with the contraction of the ventricles.
124
What does the P wave indicate in an ECG?
The time of atrial systole (contraction)
## Footnote
It represents the electrical activity associated with the contraction of the atria.
125
What is the significance of the T wave in an ECG?
It represents the repolarization of the ventricles (recovery)
## Footnote
This phase follows the contraction of the ventricles.
126
What are the three key stages of the heartbeat?
* Depolarization of the atria
* Depolarization of the ventricles
* Repolarization of the ventricles
## Footnote
These stages correspond to the contraction and recovery phases of the heart.
127
What is the role of the peripheral nervous system (PNS) in heart function?
It connects the central nervous system to other organs and regulates involuntary functions
## Footnote
This includes the autonomic nerves that control heart muscle contraction.
128
True or False: The QRS complex is smaller than the P wave.
False
## Footnote
The QRS complex is much larger than the P wave due to the larger mass of the ventricles.
129
Fill in the blank: The _____ produces an electrical impulse that causes the heart muscle to contract.
[pacemaker]
## Footnote
The pacemaker is a cluster of cells responsible for initiating heartbeats.
130
What happens during the depolarization of the atria?
The atria contract to move blood into the ventricles
## Footnote
This is represented by the P wave in an ECG.
131
What happens during the depolarization of the ventricles?
The ventricles contract to move blood around the body
## Footnote
This is represented by the QRS complex in an ECG.
132
What is the duration of the electrical changes shown in an ECG trace?
1 second
## Footnote
The ECG trace encompasses a full cardiac cycle.
133
What is a synapse?
The junction between two neurons
134
What is the presynaptic membrane?
The membrane before the synaptic gap that allows the release of neurotransmitters
135
What is contained within the presynaptic knob?
Vesicles filled with neurotransmitter
136
What occurs when an action potential arrives at a synapse?
The membrane depolarizes and calcium ion channels open
137
What role do calcium ions play in neurotransmitter release?
They cause synaptic vesicles to fuse with the presynaptic membrane
138
What happens to neurotransmitter after it is released into the synaptic cleft?
It binds with receptors on the postsynaptic membrane
139
What is the function of sodium channels during synaptic transmission?
They open to allow sodium ions to flow through, leading to membrane depolarization
140
What happens to neurotransmitters after they bind with receptors?
They can be taken back across the presynaptic membrane or diffuse away and be broken down
141
What is acetylcholine?
The first neurotransmitter discovered, involved in stimulating muscles
142
How is acetylcholine broken down in the synaptic cleft?
By acetylcholinesterase
143
Fill in the blank: Botulism toxin _______ the release of acetylcholine.
prevents
144
What is the effect of botulism toxin?
Paralyses respiratory muscles, causing suffocation and death
145
What brain chemicals are associated with Parkinson's disease and depression?
Dopamine and serotonin
## Footnote
Imbalances in these brain chemicals contribute to the development of drugs for treatment.
146
What are the main symptoms of Parkinson's disease?
* Muscle tremors (shakes)
* Stiffness of muscles
* Slowness of movement
* Poor balance and walking problems
* Difficulties with speech and breathing
* Depression
## Footnote
These symptoms result from the reduction of dopamine levels in the brain.
147
What is L-dopa and its role in treating Parkinson's disease?
L-dopa is a molecule that can be turned into dopamine to help control the symptoms of Parkinson's disease
## Footnote
Dopamine cannot move into the brain from the bloodstream, but L-dopa can.
148
What happens to dopamine-secreting neurons in Parkinson's disease?
There is death of a group of dopamine-secreting neurons in the brain
## Footnote
This results in the reduction of dopamine levels.
149
What is the function of dopamine in the brain?
Dopamine is a neurotransmitter associated with the control of movement and emotional responses
## Footnote
It is active in neurones in the frontal cortex, brain stem, and spinal cord.
150
What is serotonin and its connection to depression?
Serotonin is a neurotransmitter linked to feelings of reward and pleasure; a lack of serotonin is linked to clinical depression
## Footnote
Clinical depression includes prolonged feelings of sadness, anxiety, hopelessness, loss of interest, restlessness, and insomnia.
151
How does ecstasy (MDMA) affect serotonin levels?
MDMA prevents the reuptake of serotonin, maintaining high concentrations in the synapse
## Footnote
This leads to mood changes in users.
152
What are the ways drugs can affect synaptic functioning?
* Affect synthesis or storage of neurotransmitters
* Affect release from presynaptic membrane
* Affect interaction with receptors on postsynaptic membrane
* Be stimulatory by binding to receptors and opening sodium ion channels
* Be inhibitory by blocking receptors
* Prevent reuptake of neurotransmitters
* Inhibit enzymes breaking down neurotransmitters in the synaptic cleft
## Footnote
These effects can alter the normal functioning of the nervous system.
153
What is an SSRI and how does it work?
SSRI stands for serotonin selective reabsorption inhibitor; it binds to reuptake proteins to prevent serotonin reabsorption
## Footnote
Prozac is an example of an SSRI used to reduce depression.
154
True or False: Dopamine agonists have a similar shape to dopamine.
True
## Footnote
This similarity allows them to mimic the effects of dopamine.
155
Fill in the blank: Patients with Parkinson's disease have little of the neurotransmitter ______ in their brains.
dopamine
## Footnote
This deficiency is a key factor in the symptoms of Parkinson's disease.
156
What type of cells are plants classified as?
Eukaryotes
157
What structures are found in plant cells that are not present in animal cells?
* Chloroplasts
* Vacuole
* Cell wall
* Amyloplasts
* Middle lamella
* Plasmodesmata
158
What is the function of chloroplasts in plant cells?
Photosynthesis
159
What does the vacuole store in plant cells?
Water and other substances
160
What is the role of the tonoplast membrane?
Controls movement of molecules into and out of the vacuole
161
What is the primary function of the cell wall in plant cells?
Support and protection
162
What do amyloplasts store in plant cells?
Starch
163
What structure in plant cells helps to stick cells together?
Middle lamella
164
What are plasmodesmata?
Channels that allow communication between one cell and another
165
Fill in the blank: Plant cells include all the structures that are in animal cells, except _______.
Vacuole and centrioles
166
True or False: Plant cells contain ribosomes.
True
167
What is the function of ribosomes in plant cells?
Protein synthesis
168
Compare the presence of chloroplasts in animal, plant, and bacterial cells.
Chloroplasts are present in plant cells only.
169
What is the difference in the cell wall between plant cells and bacterial cells?
Plant cells have cellulose-based cell walls, while bacterial cells have peptidoglycan cell walls.
170
What organelle is responsible for energy production in plant cells?
Mitochondrion
171
What surrounds the nucleus in a plant cell?
Nuclear envelope
172
What is the main function of the Golgi apparatus in plant cells?
Modifying, sorting, and packaging proteins
173
What is the difference between rough and smooth endoplasmic reticulum?
Rough ER has ribosomes, while smooth ER does not.
174
What are prokaryotes?
Bacteria are prokaryotes, made of a single cell with no membrane-bound organelles.
175
What is the structure of plasmids in bacteria?
Double-stranded DNA in a circular structure that often contain additional genes aiding survival, such as antibiotic resistance or toxin producing genes.
176
What is the function of ribosomes in bacteria?
Ribosomes make proteins.
177
What is the size of bacterial ribosomes?
70S (S is a Svedberg, a measure of size by rate of sedimentation).
178
What is the nucleoid in bacteria?
A region where a single circular length of DNA is folded, carrying all essential information.
179
What is the function of the capsule in bacteria?
Protects cells from drying out, being engulfed by white blood cells, and helps cells to stick to surfaces.
180
What is the composition of the bacterial cell wall?
Made of long-chained molecules of sugar and amino acids called peptidoglycan.
181
What distinguishes gram-negative bacteria from gram-positive bacteria?
Gram-negative bacteria do not retain the gram stain due to their outer layer, while gram-positive bacteria retain the stain because of their thick peptidoglycan wall.
182
Why are gram-negative bacteria more resistant to antibiotics?
They have a cell wall with an outer membrane that protects them from antibiotics.
183
What color do gram-positive bacteria stain and why?
They stain purple due to the thick peptidoglycan wall absorbing the stain.
184
What color does the thin peptidoglycan cell wall stain with safranin?
Red.
185
Fill in the blank: Most meat pathogens are _______.
gram-positive.
186
What are the common features of all living organisms' cells?
All cells contain DNA, cytoplasm, ribosomes, and have a plasma membrane.
187
Who invented the microscope and when was it first used to see cells?
Robert Hooke invented the microscope in 1665.
188
What is the limiting factor of light microscopes?
The wavelength of light.
189
What type of microscope allows for more detail in viewing cells?
Electron microscope.
190
What is a key limitation of electron microscopes?
They can only examine dead material.
191
What type of ribosomes do bacterial cells have?
70S ribosomes.
192
What type of ribosomes do plant and animal cells have?
80S ribosomes.
193
What are organelles?
Structures in cells with specialised functions often bound by a membrane.
194
What are the visible structures of eukaryotic cells under a light microscope?
Plasma membrane, nucleus, and nucleolus.
195
What is the function of the plasma membrane?
Protects cell from its surroundings and regulates movement of substances in and out of cells.
196
What is a vesicle?
A small, membrane-bound sac that transports and stores substances in the cell.
197
What is the rough endoplasmic reticulum (rER)?
A series of single, flattened sacs enclosed by a membrane with ribosomes on the surface.
198
What is the function of the nucleus?
Region of dense DNA and protein, makes ribosomes.
199
What are centrioles?
Two hollow cylinders arranged at right-angles to each other that make the spindle in cell division.
200
What is the smooth endoplasmic reticulum (sER)?
A series of single, tubular sacs made of membrane where lipids are made.
201
What is the function of lysosomes?
Contains digestive enzymes that destroy old organelles and pathogens.
202
What is the structure and function of mitochondria?
Surrounded by a double membrane, it is the site of respiration containing 70S ribosomes and DNA.
203
What is the Golgi apparatus?
A series of single, curved sacs enclosed by a membrane that modifies proteins and packages them in vesicles for transport.
204
What is cytoplasm?
Fluid that fills a cell, containing many dissolved molecules and the site of many metabolic processes.
205
Fill in the blank: All cells have the four features: DNA, cytoplasm, ribosomes, and _______.
plasma membrane.
206
True or False: Electron microscopes can be used to view living cells.
False.
207
List three organelles surrounded by a double membrane.
* Mitochondrion
* Nucleus
* Chloroplast (if applicable, in plant cells).
208
List the organelles not surrounded by a membrane.
* Ribosomes
* Centrioles.
209
List organelles surrounded by a single membrane.
* Vesicles
* Lysosomes
* Golgi apparatus
* sER
* rER.
210
What are the common features of all living organisms' cells?
All cells contain DNA, cytoplasm, ribosomes, and have a plasma membrane.
211
Who invented the microscope and when was it first used to see cells?
Robert Hooke invented the microscope in 1665.
212
What is the limiting factor of light microscopes?
The wavelength of light.
213
What type of microscope allows for more detail in viewing cells?
Electron microscope.
214
What is a key limitation of electron microscopes?
They can only examine dead material.
215
What type of ribosomes do bacterial cells have?
70S ribosomes.
216
What type of ribosomes do plant and animal cells have?
80S ribosomes.
217
What are organelles?
Structures in cells with specialised functions often bound by a membrane.
218
What are the visible structures of eukaryotic cells under a light microscope?
Plasma membrane, nucleus, and nucleolus.
219
What is the function of the plasma membrane?
Protects cell from its surroundings and regulates movement of substances in and out of cells.
220
What is a vesicle?
A small, membrane-bound sac that transports and stores substances in the cell.
221
What is the rough endoplasmic reticulum (rER)?
A series of single, flattened sacs enclosed by a membrane with ribosomes on the surface.
222
What is the function of the nucleus?
Region of dense DNA and protein, makes ribosomes.
223
What are centrioles?
Two hollow cylinders arranged at right-angles to each other that make the spindle in cell division.
224
What is the smooth endoplasmic reticulum (sER)?
A series of single, tubular sacs made of membrane where lipids are made.
225
What is the function of lysosomes?
Contains digestive enzymes that destroy old organelles and pathogens.
226
What is the structure and function of mitochondria?
Surrounded by a double membrane, it is the site of respiration containing 70S ribosomes and DNA.
227
What is the Golgi apparatus?
A series of single, curved sacs enclosed by a membrane that modifies proteins and packages them in vesicles for transport.
228
What is cytoplasm?
Fluid that fills a cell, containing many dissolved molecules and the site of many metabolic processes.
229
Fill in the blank: All cells have the four features: DNA, cytoplasm, ribosomes, and _______.
plasma membrane.
230
True or False: Electron microscopes can be used to view living cells.
False.
231
List three organelles surrounded by a double membrane.
* Mitochondrion
* Nucleus
* Chloroplast (if applicable, in plant cells).
232
List the organelles not surrounded by a membrane.
* Ribosomes
* Centrioles.
233
List organelles surrounded by a single membrane.
* Vesicles
* Lysosomes
* Golgi apparatus
* sER
* rER.
234
What are the basic units of life?
Cells
## Footnote
All living things are made of cells and all cells come from other cells.
235
What is the purpose of a microscope?
To magnify images for clearer viewing of cells and their structures
## Footnote
Microscopes allow for the examination of specimens at a microscopic level.
236
How is total magnification calculated?
Total magnification = magnification of eyepiece lens X magnification of objective lens
## Footnote
The eyepiece lens usually has a magnification of X10 and the objective lens can be up to X100.
237
What is the greatest total magnification achievable with a light microscope?
X1000
## Footnote
This is achieved by combining a X10 eyepiece lens with a X100 objective lens.
238
What is a specimen in microscopy?
The material to be viewed on the slide
## Footnote
Specimens need to be thin enough for light or an electron beam to pass through.
239
What is the function of a coverslip in microscopy?
To protect the specimen and the lens
## Footnote
It is placed over the specimen on the slide.
240
What role do stains play in microscopy?
They help to distinguish different features in the specimen
## Footnote
Stains enhance contrast in the observed structures.
241
What is the magnification of the eyepiece lens typically?
X10
## Footnote
This is a standard magnification for eyepiece lenses in light microscopes.
242
What is the maximum magnification of an objective lens usually found in light microscopes?
X100
## Footnote
This allows for detailed examination of specimens.
243
What is the maximum magnification achievable with an electron microscope?
Far greater than light microscopes
## Footnote
Electron microscopes can achieve much higher magnifications but can only examine dead material.
244
True or False: Electron microscopes can examine living specimens.
False
## Footnote
Electron microscopes can only be used for dead materials.
245
How do you calculate the size of a real object using magnification?
Size of real object = size of image / magnification
## Footnote
This formula allows for the conversion from image size to actual size.
246
Fill in the blank: A structure viewed under a light microscope with a magnification of x400 measured 7 divisions, each equal to 0.06 mm. The real length of the structure is _______.
0.42 mm
## Footnote
Calculation: 7 divisions * 0.06 mm/division = 0.42 mm.
247
What is the smallest unit of measurement equivalent to 1 micrometer?
1 x 10^-6 m
## Footnote
1 micrometer (1 um) is equal to 0.001 mm.
