Organelles And Their Functions

Question 1

What is the structure and function of a nucleus?

Answer 1

Structure:
- enclosed by a double membrane with nuclear pores.
- contains linear DNA.
- contains a nucleolus which produces rRNA.
Function:
- codes for proteins with the DNA it contains.
- produces ribosomes.

Question 2

What is the structure and function of a mitochondrion?

Answer 2

Structure:
- enclosed by a double membrane.
- the inner membrane is folded (cristae).
- contains a fluid interior (matrix).
- contains its own DNA and 70s ribosomes.
Function:
- carries out aerobic respiration which produces energy.

Question 3

What is the structure and function of smooth endoplasmic reticulum?

Answer 3

Structure:
- a system of flattened membrane sheets.
Function:
- synthesises and transports fats.

Question 4

What is the structure and function of rough encloplasmic reticulum?

Answer 4

Structure:
- a system of flattened membrane sheets.
- has ribosomes attached.
Function:
- synthesises and transports proteins to the golgi apparatus.

Question 5

What is the structure and function of the Golgi apparatus?

Answer 5

Structure:
- stack of flattered sacs, each surrounded by a membrane.
- Golgi vesicles form at the end of the sacs.
Function:
- modifies and packages proteins.
- Produces vesicles/lysosomes.

Question 6

What is the structure and function of vesicles?

Answer 6

Structure:
- a small fluid filled sphere of membrane.
Function:
- transports substances around and out of the cell.

Question 7

What is the structure and function of a lysosome?

Answer 7

Structure:
- a type of vesicle containing the enzyme ‘lysozymes’.
Function:
- contains digestive enzymes which digest bacteria and viruses.

Question 8

What is the structure and function of ribosomes?

Answer 8

Structure:
- made up of protein and rRNA.
- NOT surrounded by a membrane.
- found in the cytoplasm (80s) and in mitochondria and chloroplasts (70s).
Function:
- carrying out protein synthesis by joining amino acids.

Question 9

What is the structure and function of a chloroplast?

Answer 9

Structure:
- enclosed by a double membrane
- contains many thylakoid disks which contain chlorophyll pigment.
- even stack of thylakoid disks is called a grana.
- contains a fluid interior (the stroma).
- contains its own DNA and 70s ribosomes.
Function:
- carries out photosynthesis to produce glucose.

Question 10

What is the structure and function of a vacuole?

Answer 10

Structure:
- a large, permanent single membrane bound structure containing fluid.
- the membrane is called the tonoplast.
Function:
- storage for chemicals, (eg. Glucose, amino acids & minerals).
- provides an osmotic system for the cell.

Question 11

What is the structure and function of the cell wall?

Answer 11

Structure:
- made up of cellulose (in plant cells) microfills embedded in a polysaccharide matrix (pectin).
- small holes are found in the cell wall between cells called plasmodesmata.
Function:
- prevents cell from bursting.
- allows movement of substances from cell to cell.

Question 12

What are the structural adaptations of epithelial cells and, how do these help with it’s function?

Answer 12

• Are columnar in shape and, specifically adapted for the absorption of digested foods.
• Have a folded cell membrane (microvilli) which, provides a larger S.A. for optimal absorption.
• Numerous mitochondria are present, this increases the rate of respiration meaning more ATP is produced so, there is more energy available for the active uptake of digested food molecules.

Question 13

What are the structural adaptations of palisade cells and, how do these help with it’s function?

Answer 13

• these cells are found below the upper epidermis of a leaf and are adapted to photosynthesise.
• they have many chloroplasts which contain the green pigment chlorophyll that is needed for photosynthesis
• have thin cell walls which provide a short diffusion pathway for the entry of Carbon dioxide.
• are columnar cells so have a larger S.A. for uptake of co2.
• the cells are arranged vertically so there are less cell walls for the light to pass through.

Question 14

Describe the role of organelles in the production and secretion of amylase.

Answer 14

1) nucleus contains the genetic code for amylase in genes/ on chromosomes.
2) mRNA leaves the nucleus through the nuclear pore.
3) mRNA will bind to the ribosome on the rough endoplasmic reticulum.
4) protein synthesis occurs producing amylase.
5) The Golgi body processes and packages amylase into vesicles.
6) vesicle moves toward the cell membrane.
7) The vesicle will fuse with the cell membrane and amylase is released from the cell.