Chapter 2.5 - The Ultrastructure Of Plant Cells

Question 1

Cellulose cell wall

Answer 1

Surround plant cell wall
Freely permeable
Give shape
Contents of cell press again, making it rigid
Supports cell and plant
Defence mechanism (protects contents against invading pathogens)

Question 2

Vacuoles

Answer 2

Membrane lined (tonoplast) saca in cytoplasm
Contains cell sap
Important in maintenance of turgor (so contents of cell push against the cell wall)
Selectively permeable
Small and transient in animal cells

Question 3

Chloroplasts

Answer 3

Responsible for photosynthesis in plant cells
Found in leaves and stems (green parts)
Double membrane structure (similar to mitochondria)
Fluid enclosed is stroma
Flattened sacs formed from inner network of membranes - thylakoids
Stacked thylakoids- granum
Grana joined by lamellae
Grana contain chlorophyll where light dependent reactions take place during photosynthesis
Starch produced by photosynthesis is present as starch grains
Contain own dna and ribosomes
Make own proteins
Internal membrane provides large surface area needed for enzymes, proteins and pigment molecules necessary for photosynthesis