B6a: Understanding microbes

Question 1

Describe how the parts of bacterial cells relate to their function(3)

Answer 1

cell wall; maintains shape of cell, prevents bursting

bacterial flagellum; movement

bacterial DNA (nucleoid); controls cell’s activities and replication

Question 2

Main shapes of bacteria (4)

Answer 2

spherical (cocci)

rod (bacilli)

spiral (spirili)

curved rods (vibrio)

Question 3

How do bacteria reproduce?

Answer 3

asexually via binary fission; (they divide into two very rapidly (in suitable conditions); they are clones of each other)

Question 4

Describe aseptic techniques for culturing bacteria on an agar plate (4)

Answer 4

wear gloves, keep hair tied back so doesn’t fall

sterilise equipment (pass inoculation loop through flame to kill unwanted bacteria)

seal dish once bacteria transferred

dispose cultures safely after use

Question 5

How are bacteria well adapted and what allows them to do this(2+2)

Answer 5

can survive on an enormous range of energy sources

can exploit a very wide range of habitats

some can consume huge range of organic nutrients from dead bodies

some make their own nutrients

Question 6

Explain the consequences of very rapid bacterial reproduction (2)

Answer 6

if food in warm room w/ enough nutrients, bacteria reproduce rapidly, leading to spoilage of food

if disease­ causing bacteria enter body + reproduce too rapidly in body for immune system to deal with it causes disease

Question 7

Explain reasons for the safe handling of bacteria

Answer 7

To avoid contamination of people, animals or food

Question 8

What is the optimum growth rate of yeast controlled by? (4)

Answer 8

availability of food, +glucose, +rate of reproduction

pH; highest at optimum pH; extreme pH, stops reproducing, enzymes denature

temperature; rate doubles for every 10C rise until optimum reached, then enzymes denature

removal of waste products; more toxic waste products (ethanol) means lower ­rate of reproduction

Question 9

Describe the structure of viruses

Answer 9

a protein coat surrounding a strand of genetic material

Question 10

Describe the actions of viruses (3)

Answer 10

can only reproduce in other living cells (host)

can only attack specific host cells (animal viruses cannot attack plant cells)

may attack plant, bacterial or animal cells

Question 11

How do viruses reproduce? (4)

Answer 11

attaches to specific host cell

injects its genetic material into the cell

viral genes cause host cell to make the components of new viruses

causes the host cell to split open to release the new viruses