2.5 - Ultrastructure Of Plant Cells

Question 1

Describe the structure of a chloroplast

Answer 1

• vesicular plastid with double membrane
• have flattened disc stacks to form granum
• grana are joined by membranes called lamellar and contain chlorophyll pigments
• stroma - fluid - filled matrix

Question 2

What’s the function of chloroplasts?

Answer 2

Site of photosynthesis to convert solar energy to chemical energy

Question 3

What’s the function of the mitochondria?

Answer 3

Site of aerobic respiration to produce ATP

Question 4

Describe the structure of a lysosome

Answer 4

•Sacs are surrounded by single membrane embedded H+ pump maintains acidic conditions contains digestive hydrolyses enzymes
• glycoprotein coat protects cell interior ;
- digests contents of phagosome
- exocytosis of digestive enzymes

Question 5

Describe the structure of a plant cell wall

Answer 5

•Made of B cellulose micro fibrils for mechanical strength
• fully permeable to substances
• thin layer is called middle lamella which separates the adjacent cell walls

Question 6

Describe the function of a plant cell wall

Answer 6

• gives mechanical strength
• plant cell support and shape
• contents of plant cells can push against the cell wall

Question 7

What are bacterial and fungal cell walls made of ?

Answer 7

Bacteria : peptidoglycan
Fungi : chitin

Question 8

Describe the structure of the centrioles

Answer 8

•Spherical group of 9 microtubules arranged in triples
•Located in centrosomes

Question 9

Describe the function of centrioles

Answer 9

•Makes a copy of itself during cell division and helps to form the spindle in cell division
• for locomotion

Question 10

Describe the structure of the flagella

Answer 10

• 9+2 arrangement
• hollow helical tube made of the protein flagellin

Question 11

Describe the function of the flagella

Answer 11

• whip like enables cell mobility
• microtubules contract to make the flagellum move
• propel cells forward eg. Sperm cells

Question 12

Describe the structure of cilia

Answer 12

•Hairlike protrusions on eukaryotic cells
• 9+2 arrangement
• pair of parallel microtubules slide over each other causing cilia to move in a beating motion

Question 13

Describe the function of the cilia

Answer 13

Can be stationary or mobile

Mobile cilia :
•Beat in a rhythmic manner creating a current and cause fluids or objects adjacent to the cell to move
Eg. Present in the trachea to move mucus away from the lungs
Fallopian tubes to move egg cells from the ovary to the uterus

Question 14

What is the structure of the large permanent vacuole ?

Answer 14

• membrane lined sacs in the cytoplasm containing cell sap
• membrane is called a tonoplast and is selectively permeable which means some molecules can pass through
• the fluid is a solution of mineral salts , sugars , amino acids and wastes

Question 15

What is the function of the vacuole?

Answer 15

• supports herbaceous plants by making cells turgid
• maintains shape and gives support by maintaining turgor pressure
• sugars and amino acids act as a temporary food store