Cell Biology Flashcards
1
Q
What are the two distinct types of cells?
A
Eukaryotic and prokaryotic cells
2
Q
What is a defining feature of eukaryotic cells?
A
Their genetic material (DNA) is enclosed within a nucleus
3
Q
What type of cells are bacterial cells?
A
Prokaryotic cells
4
Q
How is the genetic material organized in prokaryotic cells?
A
It is found as a single loop of DNA within the cytoplasm
5
Q
What is the size range of eukaryotic cells?
A
Usually between 10 and 100 µm
6
Q
What is the size of prokaryotic cells compared to eukaryotic cells?
A
Prokaryotic cells are much smaller, measuring ~ 1 µm
7
Q
How many micrometers are in one millimeter?
A
1000 µm
8
Q
Convert 1 µm to mm.
A
0.001 mm
9
Q
List the main subcellular structures in animal cells.
A
- Nucleus
- Cell membranes
- Mitochondria
- Ribosomes
- Cytoplasm
10
Q
What additional structures do plant cells have compared to animal cells?
A
- Cell wall made of cellulose
- Permanent vacuole filled with cell sap
- Chloroplasts
11
Q
What is a specialised cell?
A
A cell that has a structure that aids its specific function
12
Q
What process allows cells to specialise?
A
Differentiation
13
Q
What is the function of nerve cells?
A
Conduction of electrical impulses
14
Q
What special features do muscle cells have?
A
- Many mitochondria
- Protein filaments that can slide over each other
15
Q
What is the function of sperm cells?
A
Transfer of genetic material to an egg cell for fertilisation
16
Q
What aids in the absorption of water and mineral ions in root hair cells?
A
Increased surface area due to extensions of the cytoplasm
17
Q
What is the function of xylem vessels?
A
Transport of water and dissolved ions
18
Q
What are phloem cells adapted for?
A
Transport of dissolved sugars and amino acids
19
Q
What is cell differentiation?
A
The process by which a cell changes to become specialised
20
Q
What type of cells retain the ability to differentiate throughout the life of a plant?
A
Many types of plant cells
21
Q
What advancement in microscopy occurred in the 20th century?
A
Introduction of the first electron microscopes
22
Q
Why are electron microscopes better than light microscopes?
A
They provide much higher resolution and magnification
23
Q
What is the equation for magnification?
A
Magnification = Drawing size ÷ Actual size
24
Q
How do you find the actual size of a cell using magnification?
A
Actual size = Image size ÷ Magnification
25
What should you always check when performing magnification calculations?
The units that have been given
26
What unit should measurements often be in for magnification calculations?
Millimeters (mm)
27
What is the conversion factor between millimeters and micrometers?
1 mm = 1000 µm
28
What is the aim of using a light microscope in practical biology?
To observe, draw, and label a selection of plant and animal cells, including a magnification scale
29
What stains for and onion cells?
Iodine
30
What should you avoid when preparing a microscope slide?
Smudging the glass slide or trapping air bubbles under the coverslip
31
What is binary fission?
A type of simple cell division where bacteria multiply by replicating their genetic material and dividing
32
How does the number of cells change with each division during binary fission?
The number of cells increases by a power of 2 each time.
33
What is the maximum allowed temperature for bacterial growth in a school lab?
25 °C
34
What are the two types of media bacteria can be grown in?
* Nutrient broth solution * Agar gel plate
35
What is the purpose of aseptic techniques in microbiology?
To grow uncontaminated cultures of microorganisms.
36
What should you do to reduce the risk of contamination when using a petri dish?
Only lift the lid a little.
37
True or False: It is important to measure the radius of the inhibition zone when calculating its area.
False. Measure the diameter instead.
38
What is the formula to calculate the area of the inhibition zone?
Area = π * (radius)^2
39
What is meant by 'mean division time' in bacterial populations?
The average amount of time it takes for a bacterial cell to divide.
40
What is the aim of the required practical on bacterial growth?
To investigate the effect of antiseptics or antibiotics on bacterial growth.
41
What should one of the paper discs placed on the agar plate contain in the bacterial growth practical?
Sterile water
42
What happens to the agar where the concentration of an antiseptic is sufficient to prevent bacterial growth?
The agar will remain clear.
43
What is the importance of incubating the plates in the bacterial growth practical?
Allows bacteria to multiply by binary fission.
44
How should the diameter of each clear zone be measured for accuracy?
At least twice at 90° angles to each other.
45
Fill in the blank: The presence of competing species can affect the _______ of microbial cultures.
Growth
46
What are chromosomes?
Thread-like structures found in the nucleus of eukaryotic cells made from coiled strands of DNA
## Footnote
Each chromosome consists of one DNA molecule.
47
How many chromosomes do humans have?
46 chromosomes in 23 pairs
## Footnote
This is typical for diploid organisms.
48
What happens to red blood cells regarding chromosomes?
They lose their nuclei and therefore have no chromosomes.
49
What is the cell cycle?
A series of stages in the life cycle of a cell, including growth phase, mitosis, and cytokinesis.
50
What occurs during the growth phase of the cell cycle?
Doubling of genetic material and increase in subcellular structures such as ribosomes and mitochondria.
51
What is mitosis?
A stage in the cell cycle when the nucleus divides to produce two identical daughter cells.
52
What are chromatids?
Each strand of a replicated chromosome, which are attached to each other before cell division.
53
What is cytokinesis?
The process of dividing the cytoplasm and cell membrane, resulting in two new daughter cells.
54
True or False: You need to know the names or phases of mitosis for the AQA GCSE exam.
False.
55
What is the role of mitosis in multicellular organisms?
To facilitate growth and development by increasing cell number.
56
What is a stem cell?
An undifferentiated cell capable of dividing to form various types of cells.
57
What is the difference between embryonic and adult stem cells?
Embryonic stem cells can differentiate into any cell type, while adult stem cells have limited differentiation potential.
58
What are meristem cells in plants?
Unspecialised cells that can differentiate into various plant cell types during growth.
59
How can stem cells be used in medicine?
To repair damaged organs and potentially cure diseases such as diabetes and paralysis.
60
What is therapeutic cloning?
The process of producing an embryo with the same genes as the patient for stem cell treatment.
61
Why are plant stem cells obtained from meristems considered ethically unobjectionable?
They can be obtained easily and do not involve the same ethical concerns as human embryonic stem cells.
62
What is a potential benefit of cloning rare plant species?
To protect them from extinction and maintain biodiversity.
63
Fill in the blank: The number of specialized cell types in the human body is approximately _______.
250.
64
What happens to specialized cells that can divide by mitosis?
They produce daughter cells of the same specialized type and lose differentiation ability.
65
What is the significance of the X-shaped chromosomes during cell division?
They indicate that the genetic material has been duplicated and is ready for separation.
66
What is the importance of cloning crop plants with special features?
To produce large numbers of identical plants, reducing the need for pesticides and fostering environmental benefits.
67
What is diffusion?
Diffusion is the spreading out of the particles of any substance in solution or gas, resulting in a net movement from higher to lower concentration.
68
What are the three transport processes used by living organisms for exchange?
* Diffusion
* Osmosis
* Active transport
69
Is diffusion a passive or active process?
Diffusion is an entirely passive process.
70
What factors affect the rate of diffusion?
* Temperature
* Concentration gradient
* Surface area to volume ratio
71
What does it mean for a cell membrane to be 'partially permeable'?
It means that some substances can pass through the membrane while others cannot.
72
Which substances can diffuse across the cell membrane?
* Oxygen
* Carbon dioxide
73
What is the significance of the concentration gradient in diffusion?
The movement of substances is driven by the concentration gradient between the cell and its environment.
74
True or False: Larger organisms rely solely on diffusion for substance exchange.
False.
75
What is the relationship between surface area and volume ratio in unicellular organisms?
Unicellular organisms have a relatively large surface area compared to their volume.
76
How does the small intestine increase its efficiency for absorption?
It has a highly folded surface and a single layer of epithelial cells, which increases surface area and decreases diffusion distance.
77
What is the role of alveoli in the lungs?
Gas exchange between air in the alveoli and the blood.
78
How are fish gills adapted for gas exchange?
* Made of filaments covered in lamellae
* Dense capillary network
* Counter-current flow with water
79
What is osmosis?
Osmosis is the diffusion of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane.
80
Fill in the blank: Osmosis refers specifically to the movement of _______.
[water molecules]
81
What happens to plant tissue in a dilute solution during osmosis?
Water moves into the plant tissue, causing it to gain mass.
82
What is the purpose of the required practical on osmosis?
To investigate the effect of different concentrations of salt or sugar solutions on the mass of plant tissue.
83
What is the independent variable in the osmosis practical?
Concentration of salt or sucrose solution.
84
What should be controlled in the osmosis experiment?
* Type and volume of solute
* Temperature
85
True or False: Osmosis can occur in any type of solution.
False.
86
Which plant structure is adapted to absorb water and minerals?
Root hair cells.
87
What role do stomata play in leaves?
They allow air to circulate inside the leaf for gas exchange.
88
What adaptations do multicellular organisms have for efficient material exchange?
* Large surface area
* Thin barriers for short diffusion paths
* Network of blood vessels
89
How does the temperature affect diffusion?
Higher temperature increases kinetic energy, leading to faster diffusion.
90
What is the purpose of measuring percentage change in mass and length in the context of osmosis?
To analyze the movement of water in and out of potato cells during osmosis
## Footnote
This measurement helps determine the effect of different solute concentrations on potato mass.
91
What does a positive percentage change in mass indicate about the potato's interaction with the solution?
The potato has gained water by osmosis
## Footnote
This means the surrounding solution is more dilute.
92
What does a negative percentage change in mass suggest about the potato's interaction with the solution?
The potato has lost water, indicating a more concentrated solution surrounding it.
93
What does the point where the line crosses the X-axis in an osmosis graph represent?
The concentration of sugar/salt inside the potato, where no water has been lost or gained.
94
True or False: Diffusion and osmosis require energy to move substances across cell membranes.
False
## Footnote
Diffusion and osmosis are passive processes that rely on concentration gradients.
95
What is active transport?
The movement of substances across a cell membrane against a concentration gradient using energy from respiration.
96
Fill in the blank: Active transport moves substances from a more _______ solution to a more concentrated solution.
dilute
97
What role do protein carrier molecules play in active transport?
They facilitate the movement of substances into or out of the cell.
98
Give an example of active transport in plants.
Root hair cells absorb magnesium ions from the soil against the concentration gradient.
99
What are nitrate ions needed for in plants?
To make amino acids and therefore for protein synthesis.
100
How does active transport benefit animals during digestion?
It allows glucose to be absorbed into the bloodstream from the small intestine even when blood glucose levels are higher.
101
What are the three main processes for the transport of substances into and out of cells?
Diffusion, osmosis, and active transport.
102
What is the purpose of sports drinks during exercise?
To replace lost water, salts, and glucose from the body.
103
What is the consequence of an imbalance in water and ion concentrations in the body?
Cells can either dehydrate and shrink or swell and burst.
104
What defines isotonic sports drinks?
They contain similar concentrations of salt and sugar as the human body.
105
What are hypertonic sports drinks used for?
To provide high levels of salt and sugar for absorption during intense physical exercise.
106
What is the benefit of hypotonic sports drinks?
They facilitate rapid rehydration as water is drawn into the bloodstream by osmosis.
107
True or False: Glucose allows energy to be produced during aerobic respiration.
False
## Footnote
Energy cannot be created or destroyed; it is released during the breakdown of glucose.
108
What should be considered when choosing sports drinks for individuals with diabetes?
Sports drinks can be unhealthy and may cause illness due to high sugar content.
