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Cellular Biology Review
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Cellular Biology Review
Cellular Biology Review
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1
Question
What is one key structural feature of prokaryotic cells that distinguishes them from eukaryotic cells?
Answer
Prokaryotic cells lack a nucleus, whereas eukaryotic cells have a nucleus.
2
Question
How does the arrangement of genetic material in prokaryotic cells differ from its arrangement in eukaryotic cells?
Answer
In prokaryotic cells, genetic material is circular and free-floating in the cytoplasm; in eukaryotic cells, it is linear and enclosed within a nucleus.
3
Question
Identify one structure found in plant cells but not in animal cells, and explain why it is important for plants.
Answer
Plant cells have a cell wall, which provides rigidity and support, helping plants maintain their shape and stand upright.
4
Question
What is the name of the process that leads to cells becoming specialised for specific roles?
Answer
The process is called differentiation.
5
Question
Explain how mitochondria help a sperm cell carry out its function.
Answer
Mitochondria provide energy through respiration, enabling the sperm cell to swim and reach the egg cell for fertilisation.
6
Question
How do you calculate the magnification of a microscope given the actual size and the size of the image?
Answer
Magnification = size of the image ÷ actual size.
7
Question
Why might a student be unable to see cells when placing a piece of onion directly on a slide under a microscope?
Answer
Because the onion cells are transparent and need to be stained to be visible under a microscope.
8
Question
Suggest two things a student can do to prepare a microscope slide to avoid seeing only faint outlines of cells and bubbles.
Answer
1. Use a suitable stain to make cell structures visible. 2. Avoid trapping air bubbles when placing the coverslip.
9
Question
What are the advantages of using an electron microscope to view cells compared to a light microscope?
Answer
Electron microscopes have higher magnification and better resolution, allowing visualization of cell ultrastructure and organelles clearly.
10
Question
Why must aseptic techniques be used to prepare an uncontaminated bacterial culture?
Answer
To prevent contamination from unwanted microorganisms which could interfere with the experiment and to ensure the accuracy of results.
11
Question
Describe key steps in preparing an uncontaminated bacterial culture and reasons for each step.
Answer
Sterilise Petri dishes and culture media to kill unwanted microbes; use sterile inoculating loops to transfer bacteria; flame the neck of nutrient broth bottles to prevent contamination; seal plates to stop airborne microbes entering; incubate at appropriate temperatures avoiding excess heat.
12
Question
Calculate the number of bacteria after 3 hours if the initial population is 50 cells and the mean division time is 15 minutes.
Answer
Number of divisions in 3 hours = 180 minutes ÷ 15 = 12. Population = 50 × 2¹² = 50 × 4096 = 204,800 bacteria.
13
Question
Explain two ways the skin protects the human body against pathogens.
Answer
1. Acts as a physical barrier preventing pathogen entry. 2. Produces antimicrobial secretions that kill or inhibit pathogens.
14
Question
What is a vector in disease transmission? Identify the vector for malaria.
Answer
A vector is an organism that carries and transmits a pathogen to another organism. The vector for malaria is the female Anopheles mosquito.
15
Question
Identify one method used to control the spread of malaria and explain how it works.
Answer
Using insecticide-treated mosquito nets prevents mosquito bites and thus stops transmission of the malaria parasite.
16
Question
Describe the role of white blood cells in the immune system and how they respond to a vaccine.
Answer
White blood cells detect and engulf pathogens or produce antibodies. Vaccines stimulate white blood cells to produce antibodies, preparing the immune system for future infections.
17
Question
What type of respiration occurs in a person running on a treadmill assuming sufficient oxygen?
Answer
Aerobic respiration.
18
Question
Describe the functions of plasma, red blood cells, white blood cells, and platelets in the blood.
Answer
Plasma transports nutrients, hormones, and waste; red blood cells carry oxygen using haemoglobin; white blood cells fight infections; platelets help blood clotting to stop bleeding.