Cell Biology Q&a

CELL BIOLOGY 1

1. What do eukaryotic cells contain?

2. What do prokaryotic cells contain?

3. Which is smaller, a prokaryotic cell or eukaryotic cell?

4. Give two examples of eukaryotic cells.

5. Give one example of a prokaryotic cell.

6. Describe the function of the nucleus.

7. Describe the function of the chloroplast.

8. Describe the function of the cell membrane.

9. Describe the function of the mitochondria.

10.Describe the function of the plasmid.

11.Describe the function of the cytoplasm.

12.Describe the function of the ribosomes.

13.What does the permanent vacuole in a plant cell contain?

14.In addition to the parts found in animal cells, name three parts plant cells often have.

15.Name the substance found in plant and algal cell walls.

16.Describe the role of cellulose in plant and algal cell walls.

17.Describe the function of a sperm cell.

18.Describe the adaptations of a sperm cell.

19.Describe the function of a nerve cell.

20.Describe the adaptations of a nerve cell.

21.Describe the function of a muscle cell.

22.Describe the adaptations of a muscle cell.

23.Describe the function of a root hair cell.

24.Describe the adaptations of a root hair cell.

25.Describe the function of a xylem cell.

26.Describe the adaptations of a xylem cell.

27.Describe the function of a phloem cell.

28.Describe the adaptations of a phloem cell.

ANSWERS

1. Cell membrane, cytoplasm and genetic material (DNA) enclosed in a nucleus.

2. Cell membrane, cytoplasm, the genetic material is not enclosed in a nucleus. The DNA is a single loop and there may be one or more rings of DNA called plasmids.

3. Prokaryotic

4. Animal and plant cells

5. Bacterial cell

6. Contains genetic material, which controls the activities of the cell

7. Contain chlorophyll, absorbs light energy for photosynthesis

8. Controls the movement of substances into and out of the cell

9. Most energy is released by respiration here

10.Small ring of DNA often used as a vector in genetic modification

11.Most chemical processes take place here, controlled by enzymes

12.Protein synthesis happens here

13.Filled with cell sap to help keep the cell turgid

14.Cell wall, chloroplast, permanent vacuole (any order)

15.Cellulose

16.Strengthens the cell

17.to fertilise an egg

18.A. Streamlined with a long tail to swim to the egg.

B. Acrosome in the head containing enzymes to digest the egg cell membrane.

C. Large number of mitochondria in the mid-section to release energy for movement.

19.to carry electrical signals.

20.A. Long to carry signals long distances.

B. Branched connections to connect to other nerve cells and form a network around the body.

C. Insulating sheath to enhance transmission of electrical signals.

21.to contact and relax to cause movement

22.A. Contain a large number of mitochondria to release energy from respiration for movement.

B. Long so that there is enough space to contract.

23.to absorb water and mineral ions.

24.Hair like projections to increase the surface area.

25.to carry water and mineral ions in plants.

26.A. Form hollow xylem tubes made of dead tissue.

B. Long cells with walls toughened by lignin.

C. Water and minerals flow from the roots towards the leaves only in one direction in a process called TRANSPIRATION.

27.to carry glucose around the plant.

28.A. Form phloem tubes made of living tissue.

B. Cells have end plates with holes in them.

C. Glucose in solution moves from the leaves to growth and storage tissues in a process called TRANSLOCATION.

CELL BIOLOGY 2

1. Explain how electron microscopy has increased understanding of sub-cellular structures.

2. Use the terms magnification and resolution to describe the differences between a light microscope and an electron microscope.

3. State the equation used to calculate magnification.

4. What does the nucleus of a cell contain?

5. What does each chromosome contain?

6. How are chromosomes normally found in body cells?

7. What happens to the genetic material during the cell cycle?

8. What happens to the subcellular structures before cell division?

9. What happens to the DNA before cell division?

10.What happens to the chromosomes during mitosis?

11.What happens in the final stage of cell division?

12.What type of cell division happens in mature animals?

13.Why do cells divide by mitosis?

14.Define stem cell.

15.Describe the function of stem cells in embryos.

16.Describe the function of stem cells in adult animals.

17.Describe the function of stem cells in meristems in plants.

18.Name two conditions which stem cells can be used to treat.

19.What is meant by the term therapeutic cloning.

20.What are the disadvantages of using stem cells.

21.Give two reasons for using stem cells from meristems in plants to produce plants quickly and economically.

22.Stem cells can be found in the growing areas of plants. What are these growing areas of a plant celled?

23.Which type of cells differentiate at an early stage?

24.Which type of cells retain the ability to differentiate throughout their lifetime.

ANSWERS

1. Electron microscopes have meant scientists can see more sub-cellular structures such as chloroplasts a single mitochondrion in detail.

2. Light microscopes use light rays whereas electron microscopes use electron beams. The magnification of a light microscope is lower (1500 times) than an electron microscope (2000 000 times). The resolution of a light microscope is lower (200nm) than an electron microscope (0.2nm). Light microscopes are smaller and more portable than electron microscopes. Light microscopes are cheaper (£100) than an electron microscope (£100,000-£1000 000).

3. Magnification = size of image ÷ size of real object

4. The nucleus contains chromosomes which contains the instructions for making proteins and new cells.

5. DNA

6. 23 pairs (46)

7. The genetic material is doubled and then divided into two identical cells.

8. Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.

9. The DNA replicates to form two copies of each chromosome.

10.One set of chromosomes is pulled to each end of the cell and the nucleus divides.

11.The cytoplasm and cell membranes divide to form two cells that are identical to the parent cell.

12.mitosis

13.Mitosis occurs during growth and to repair or replace damaged cells.

Asexual reproduction occurs by mitosis in both plants and simple animals.

14.Stem cells are undifferentiated cells within an organism. They can produce other stem cells that can then differentiate into many different types of cells.

15.Human embryo stem cells: can be cloned and made to differentiate into most different types of human cells.

16.Human adult stem cells: can form many (but not all) types of cells including blood cells.

17.Stem cells from meristems in plants can be used to produce clones of plants quickly and economically.

18.Human stem cells can be used to help treat diseases like diabetes and paralysis.

19.Embryos produced by therapeutic cloning have the same genes as the patient. This means stem cells from the embryo are not rejected by the patient’s body. This is why they can be used for medical treatments.

20.The risks of using stem cells risks such as transfer of viral infections.

Some people have objections to stem cell use for ethical and religious reasons. During Fertility treatment doctors usually fertilise many more eggs than are going to be used. The embryos then formed are used to obtain stem cells. In the UK scientists can use these embryos for research but only under very strict guidelines.

21.Rare species: can be cloned to protect from extinction. Crop plants: with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers. e.g. potatoes, strawberries and dates

22.Meristem

23.Animal cells

24.Plant cells

CELL BIOLOGY 3

1. Define diffusion.

2. Name two substances transported into and out of cells by diffusion.

3. Name a waste product transported out of cells into blood plasma for excretion in the kidney.

4. Give three factors which affect the rate of diffusion.

5. Describe the surface area to volume ratio of a single celled organism.

6. Explain how the small intestine in mammals is adapted for exchanging materials.

7. Explain how the lungs in mammals are adapted for exchanging materials.

8. Explain how the gills in fish are adapted for exchanging materials.

9. Explain how the roots in plants are adapted for exchanging materials.

10.Explain how the leaves in plants are adapted for exchanging materials.

11.Give four factors which affect the effectiveness of a gas exchange surface.

12.Define osmosis.

13.Define active transport.

14.Describe the role of active transport in the uptake of ions in the roots.

15.Describe the role of active transport in the absorption of sugar molecules into the blood.

16.How are sugar molecules used by cells?

ANSWERS

1. Diffusion is the spreading of the particles of a gas or substances in solution, resulting in a net movement of particles from a region where they are of a higher concentration to an area of lower concentration.

2. Any two of the following: Glucose, amino acids, oxygen, urea, carbon dioxide.

3. Urea

4. Concentration gradient, temperature, surface area of the membrane

5. Large

6. Internal surface is covered in millions of folds called villi. Villi increase the surface area. Villi have a very good blood supply. This maintains the concentration gradient. Membranes of the villi are very thin to allow for a short diffusion distance.

7. Lungs contain millions of tiny air sacs called alveoli. Alveoli increase the surface area. Alveoli have a very good blood supply. This maintains the concentration gradient. Membranes of the alveoli are very thin to allow for a short diffusion distance.

8. Each gill is made of lots of thin plates called gill filaments, water with low oxygen flows over them (however, the oxygen in the blood surrounding the gills is lower). Gill filaments increase the surface area. Gill filaments are covered with lamella that increase the surface area more. Lamella have a very good blood supply. This maintains the concentration gradient as water flows in the opposite direction. Membranes of the lamellae are very thin to allow for a short diffusion distance.

9. The root surface is covered in millions of root hair cells. Root hair cells increase the surface area. Present on the mature parts of the roots. Absorb water and minerals from the soil.

10.Large surface area to absorb more light. Thin so short distance for carbon dioxide to diffuse into leaf cells. Chlorophyll absorbs sunlight for photosynthesis. Xylem and phloem to support the leaf and transport water and glucose. Stomata on the lower side of the leaf to allow gases to diffuse into and out of the leaf.

11. Having a large surface area. A membrane that is thin, to provide a short diffusion path. (in animals) having an efficient blood supply. (in animals, for gaseous exchange) being ventilated.

12.Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.

13.Active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). The energy is provided by respiration.

14.The minerals are at a higher concentration in the root hair cell than in the soil so the minerals move into the cell against the concentration gradient.

15.Active transport also occurs in the gut (small intestines) sugar (glucose) molecules are absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration.

16.Respiration