2.5 Ultrastructure of plant cells

Question 1

Explain what the cellulose cell wall is

Answer 1

• Made of cellulose
• Freely permeable so substances can pass in and out
• Gives the cell its shape
• Contents of cell press against it making it rigid
• Rigidity supports the plant cell and plant as a whole
• Defence mechanism; protects cell’s contents from pathogens

Question 2

Explain what the vacuole is

Answer 2

• Membrane lined sac in cytoplasm
• Contains cell sap
• Maintains turgor - so contents of cell push against cell wall and maintain a rigid framework for the cell

Question 3

What is the tonoplast?

Answer 3

• Vacuole’s membrane

- Selectively permeable; small molecules can pass but others can’t

Question 4

Explain what a chloroplast is

Answer 4

• Organelles responsible for photosynthesis
• Found in green parts of a plant
• Have a double membrane
• Contain DNA and ribosomes
• Can make its own protein
• -Internal membranes provide large surface area for enzymes, proteins and pigment required for photosynthesis

Question 5

What is the stroma?

Answer 5

Fluid within the chloroplast (like a cytoplasm)

Question 6

What are thylakoids?

Answer 6

An internal network of membranes in the chloroplast, forming flattened sacs

Question 7

What is a granum?

Answer 7

Several thylakoids stacked together

Question 8

What are lamellae?

Answer 8

Membranes that join a grana (plural)

Question 9

What do grana contain?

Answer 9

Chlorophyll pigments where light-dependent reactions occur during photosynthesis

Question 10

What are starch grains?

Answer 10

• Starch produced from photosynthesis

- Found in the chloroplast