2.5 - The ultrastructure of plant cells

Question 1

What are the organelles found in plant cells?

Answer 1

1. Plasma (cell surface) membrane
2. Chloroplasts
3. Rough Endoplasmic Reticulum (RER)
4. Plasmodesma
5. Mitochondrion
6. Golgi Apparatus
7. Vacuole
8. Smooth Endoplasmic Reticulum (SER)
9. Cytoplasm
10. Nuclear Envelope
11. Nucleus
12. Ribsome
13. Cell Wall

Question 2

What additional structures do plant cells have that animal cells do not?

Answer 2

Plant cells have structures such as chloroplasts, a large central vacuole, and a cell wall, which are not present in animal cells.

Question 3

What is the primary composition of plant cell walls?

Answer 3

Plant cell walls are made of cellulose, a complex carbohydrate.

Question 4

How does the cell wall contribute to the rigidity of plant cells?

Answer 4

The cell wall provides structure and shape to the plant cell by pressing against the cell membrane, making the cell rigid.

Question 5

Are plant cell walls permeable?

Answer 5

Yes, plant cell walls are freely permeable, allowing substances to pass into and out of the cell.

Question 6

What role does the cell wall play in supporting the plant?

Answer 6

The cell wall supports both individual cells and the plant as a whole by providing structural strength.

Question 7

How does the cellulose cell wall act as a defense mechanism for plant cells?

Answer 7

The cell wall protects the cell’s contents from invading pathogens by acting as a barrier.

Question 8

Are cellulose cell walls present in all plant cells?

Answer 8

Yes, all plant cells have cellulose cell walls.

Question 9

What are vacuoles?

Answer 9

Vacuoles are membrane-lined sacs that contain cell sap in plant cells.

Question 10

What is the function of vacuoles in plant cells?

Answer 10

Vacuoles are important for maintaining turgor by pushing against the cell wall, helping to maintain a rigid framework for the cell.

Question 11

What is the name of the membrane that surrounds the vacuole in plant cells?

Answer 11

The membrane surrounding the vacuole in plant cells is called the tonoplast.

Question 12

Are vacuoles in animal cells permanent?

Answer 12

No, vacuoles in animal cells are small and transient, meaning they are not permanent.

Question 13

Is the tonoplast permeable?

Answer 13

Yes, the tonoplast is selectively permeable, allowing some small molecules to pass through while blocking others.

Question 14

What is the role of the vacuole in maintaining cell rigidity?

Answer 14

The vacuole helps to maintain cell rigidity by pushing the contents against the cell wall, contributing to the cell’s turgor pressure.

Question 15

What is the main function of chloroplasts?

Answer 15

Chloroplasts are responsible for photosynthesis in plant cells.

Question 16

Where are chloroplasts found in plants?

Answer 16

Chloroplasts are found in the green parts of plants, such as the leaves and stem, but not in the roots.

Question 17

What is the structure of chloroplasts?

Answer 17

Chloroplasts have a double membrane structure and contain a fluid called the stroma. Inside, they have an internal network of membranes that form flattened sacs called thylakoids.

Question 18

What are thylakoids and how are they organized?

Answer 18

Thylakoids are flattened sacs inside chloroplasts. Several thylakoids stacked together form a structure called a granum (plural: grana), which are connected by membranes called lamellae.

Question 19

What occurs in the grana of chloroplasts?

Answer 19

The grana contain chlorophyll pigments where the light-dependent reactions of photosynthesis occur.

Question 20

Do chloroplasts contain DNA and ribosomes?

Answer 20

Yes, like mitochondria, chloroplasts contain their own DNA and ribosomes, allowing them to make their own proteins.

Question 21

What is the importance of the internal membranes in chloroplasts?

Answer 21

The internal membranes provide a large surface area for the enzymes, proteins, and pigment molecules necessary for photosynthesis.

Question 22

What is stored in chloroplasts as a result of photosynthesis?

Answer 22

Starch produced by photosynthesis is stored in the chloroplasts as starch grains.