Question

discussion: (12 marks)

1. what structures in the cell did the iodine stain? (1)
2. why would you find more mitochondria present in the cells of a runners muscle tissue versus fat cells? (2)
3. what cell organelles could you see in both plant cells (onion and aquatic)? (2)
4. describe the functions of organelles that you were able to identify in the plant cells. (2)
5. how does the arrangement of plant cells and animal cells differ? (1)
6. a) what cell organelles did you see in the aquatic plant that you did not see in the onion cells? (1)

b) what colour were they and why? (1)
c) where did you see them in the cell? (ex - in the middle, near the cell membrane, or scattered)? (1)
d) why do you think they are in this location? (1)

Explanation:

1. Iodine stains starch - rich structures. In runner's muscle tissue, mitochondria are present for energy - production. Mitochondria are more numerous in muscle cells due to high energy demands.
2. In plant cells (onion and aquatic), common organelles include nucleus, mitochondria, endoplasmic reticulum, etc. Chloroplasts are present in photosynthetic plant cells (aquatic plants may have them for photosynthesis in water), not in onion cells.
3. Organelle functions: Nucleus controls cell activities, mitochondria produce energy (ATP), endoplasmic reticulum is involved in protein and lipid synthesis.
4. Plant and animal cells differ in that plant cells have cell walls, chloroplasts (in some), and large central vacuoles, while animal cells lack these. Arrangement of organelles can vary based on cell function. For example, in plant cells, chloroplasts may be arranged to maximize light absorption.
5. In aquatic plants, organelles may be arranged to adapt to the aquatic environment, e.g., chloroplasts near the cell surface for better light capture. In onion cells, organelles are arranged for normal cell functions like storage and metabolism.
6. The location of organelles can be related to their function. For example, mitochondria are often near areas of high energy use like the cell membrane in some cells.

Answer:

1. In runner's muscle tissue, iodine may stain glycogen - containing structures. Mitochondria are present in large numbers due to high energy requirements for muscle contraction.
2. Common cell organelles in both plant cells (onion and aquatic) include the nucleus, mitochondria, ribosomes, endoplasmic reticulum, and Golgi apparatus.
3. Nucleus: Controls genetic information and cell activities. Mitochondria: Produce ATP through cellular respiration. Endoplasmic reticulum: Involved in protein and lipid synthesis.
4. Plant cells have cell walls, chloroplasts (in photosynthetic cells), and large central vacuoles. Animal cells lack these. Organelle arrangement can differ based on cell function and environment.
5. In aquatic plant cells, chloroplasts may be arranged near the cell surface for better light absorption. In onion cells, organelles are arranged for functions like storage and basic metabolism.
6. Organelles are located based on their functions. For example, mitochondria are near energy - consuming structures like the cell membrane in some cells.