Bacteria (2)

Question 1

Bacteria are ___, but the cell is simpler than those of other living organisms. However, they can carry out all the ____ of living organisms.

Answer 1

Unicellular

Functions

Question 2

What protective layer do bacteria have?

Answer 2

They have a rigid cell wall which consists of large molecules known as peptidoglycans.

Question 3

What are peptidoglycans?

Answer 3

Large molecules which make the rigid cell wall of bacterium. It is a mixture of polysaccharides and amino acids.

Question 4

Why is the plasma membrane of the bacterial cell a multipurpose structure? (2)

Answer 4

• It serves as a mitochondrion, endoplasmic reticulum and sometimes even a chloroplast
• It also controls the entry and exit of materials

Question 5

Bacteria are prokaryotes/eukaryotes.

Answer 5

Prokaryotes

Question 6

Why are bacteria prokaryotes?

Answer 6

They do not have a true nucleus.

Question 7

Why do prokaryotes not have a true nucleus? (2)

Answer 7

• No nuclear membrane

- The DNA is not combined with histone, a protein, as in eukaryote cells

Question 8

What does the single chromosome of bacterium consist of?

Answer 8

It consists of a closed loop of DNA.

Question 9

Why do bacteria which cause disease, especially bacilli, have a waxy capsule as their outermost layer?

Answer 9

Its function is to give protection against the defences of the host’s body.

Question 10

Why do some bacteria have flagella?

Answer 10

It enables them to move.

Question 11

Why do pathogenic bacteria infect our bodies?

Answer 11

In order to get food.

Question 12

What may bacteria do to us? (3)

Answer 12

• Destroy body cells which are then used as a source of food
• Absorb material directly from body fluids such as blood
• Release harmful substances, called toxins

Question 13

What do toxins do? (2)

Answer 13

• Cause symptoms like a rash or a high temperature
• Block metabolic pathways in the host cells which can have a devastating effect on the body, eg. tetanus, diphtheria, typhoid fever, staphylococcal infections, meaning-coccal meningitis and Salmonella food poisoning.

Question 14

What are the economic uses of bacteria? (8)

Answer 14

• Degrade herbicides
• Eat or neutralise toxic waste
• Synthesise riboflavin
• Separate the fibres
• Replace pesticides
• Decompose sewage wastes
• Produce food
• Make probiotics

Question 15

What probiotics?

Answer 15

Probiotics are live bacteria and yeasts that are good for you, especially your digestive system. We usually think of these as germs that cause diseases. But your body is full of bacteria, both good and bad. Probiotics are often called “good” or “helpful” bacteria because they help keep your gut healthy