UNIT 15 Drugs

Question 1

define drugs

Answer 1

any substance taken into the
body that modifies or affects chemical reactions in the body

Question 2

antibiotics kill bacteria but do not
affect _____

Answer 2

viruses & parasites - NOT targeted

Antibiotics kill bacteria bc antibiotics act on bacterial cell walls

Question 3

in america antibiotics added to livestock feed to reduce chance of sickness, what is the problem with overusing antibiotics?

Answer 3

some bacteria become more resistant to antibiotics which reduces the effectiveness of antibiotics

Question 4

ways that you can reduce the rate at which bacteria gain resistance to antibiotics?

Answer 4

Only take antibiotics when necessary as in extremely sick

• Finish your prescription of antibiotics so binary fission of resistant bacterial cells doesn’t occur

Treat specific bacteria with specific antibiotics.

High hospital hygiene levels, including regular hand washing by staff and visitors.

Patients who are infected with antibiotic resistant strains of bacteria should be isolated from other patients.

Question 5

what is MSRA? why are organisms like MRSA a risk to our use of antibioitics in future?

Bc creates SUPER BUGS we cannot treat using antibiotics

Answer 5

• Methicillin-resistant Staphylococcus aureus [e.g. of superbug; a group of bacteria that are genetically distinct from other strains of Staphylococcus aureus]
• creates contagious illness which is resistant to antibiotics and can’t be killed, harder to treat

using antibiotics only when essential
can limit the development of resistant bacteria such as MRSA

Question 6

explain why antibiotics such as penicillin kill bacteria but not viruses

Answer 6

antibiotics stop cell wall growth

viruses have no cell wall

Question 7

explain why antibiotics cannot be used to control HIV

Answer 7

antibiotics are not effective against viruses

no cell wall for antibiotics to act on

Question 8

explain why glucose and amino acids are included in the agar medium

Answer 8

glucose - provides energy/required for respiration

amino acids - used to make proteins

Question 9

explain the appearance of agar plates 3 and 4

3 - more bacteria but much much less than before
4 - less bacteria than 3

Answer 9

some bacteria were resistant to antibiotic in both S and T

both antibiotics killed bacteria

[[fewer were resistant to antibiotic T]]

Question 10

explain why many bacterial colonies were found on agar plates 5 and 6

Answer 10

• bacteria are resistant
• have reproduced
• all genetically identical so all resistant

Question 11

explain how strains of antibiotic-resistant bacteria are formed and then spread [5]

Answer 11

📍 antibiotic resistant bacteria are formed by mutation
📍 changes to gene
📍 produces different protein
📍 resistant bacteria reproduce
📍 increases risk of resistance to take antibiotics when not necessary

[[less competition, more food available for resistant bacteria]]

Question 12

suggest why there is a clear area around some of the antibiotics

Answer 12

• antibiotics diffuse through the agar
• some kill bacteria
• not all antibiotics are effective

Question 13

explain why antibiotics 1 and 5 would not be chosen to treat the gonorrhoea infection

Answer 13

bacteria grew around the discs

bacteria are resistant to antibiotics 1 and 5

Question 14

suggest why people are given the advice of completing the treatment rather than stop taking the antibiotics when they feel better [2]

Answer 14

kill all the bacteria

some bacteria still present even after person feels better

prevents bacteria becoming resistant

Question 15

Explain why
(i) only a few bacteria grew in dish B compared with dish A,
[1]
(ii) more bacteria grew in C than in B.

Answer 15

i) (most) were killed by the antibiotic

ii) (only) antibiotic-resistant bacteria transferred from B

Question 16

As the fungus grows in the fermenter, the nuclei in the fungal hyphae divide.

State the type of nuclear division that occurs during the growth of the fungus in the
fermenter

Answer 16

mitosis

Question 17

Explain why the growth of the fungus slows down and stops. [3]

Answer 17

• nutrients are used up ;
• limiting (factors) ;
• waste products accumulate ;
• wastes are toxic

Question 18

Penicillin is not needed for the growth of P. chrysogenum.

(i) State the evidence from Fig. 4.2 that shows that penicillin is not needed for this
growth. [2]

Answer 18

fungus grows when no penicillin produced ;

during first 20 hours ;

only nutrients and fungus added at the beginning ;

Question 19

The people in charge of the penicillin production emptied the fermenter at
160 hours.
Use the information in Fig. 4.2 to suggest why they did not allow the fermentation
to continue for longer.

Answer 19

penicillin production stopped

Question 20

Explain why downstream processing is necessary.

Answer 20

purifying / separating, penicillin ;
from, waste / toxins / AW ;
concentration ;
making into, pills

Question 21

The human immunodeficiency virus (HIV) infects white blood cells. The virus is reproduced inside these white blood cells.

(a) Describe what may happen to viruses that leave infected white blood cells

Answer 21

enter, blood ;

infect white blood cell

infect, brain;

Question 22

Describe the possible long-term effects of HIV on the immune system. [3]

Answer 22

infects and destroys phagocytes ;

destroys ymphocytes ;

fewer antibodies produced ;

weaker, immune response

Question 23

Describe how bacteria reproduce asexually. [2]

Answer 23

any 2 from:::

DNA replicates ;
binary fission ;
bacteria/ cell/ cytoplasm, divides into two ;

[[[cell membrane/ cell wall, develops in the middle of the cell ;]]]

Question 24

name given to
(i) the body of the fungus that grows from a single spore

(ii) the thin threads that make up the body of the fungus.

Answer 24

mycelium

ii) hypha

Question 25

Describe how a fungus, such as T. violaceum, obtains nutrients from the agar medium. [4]

Answer 25

hyphae, secrete / release ;
enzymes ;
amylase ;
breaks down starch to, maltose / glucose ;

Question 26

Suggest why antibiotics should not be used too often. [2]

Answer 26

resistant bacteria, survive ;

eventually, all become resistant ;

antibiotic no longer effective ;

Question 27

Explain the possible effect of the X-rays on the bacteria. [3]

Answer 27

X-rays caused mutations ;

change in DNA ;

ref to, gene / allele ;

mutation causes antibiotic resistance ;

Question 28

Human Immunodeficiency Virus (HIV) infects cells of the immune system.

Describe the effects of HIV on the immune system. [4]

Answer 28

HIV infects lymphocytes ;

fewer antibodies produced ;

infected cells not killed (by immune system) ;

phagocytes less effective ;

increased susceptibility to (infectious) diseases

Question 29

Describe the results shown in Fig. 4.3.

Credit will be given for using figures from
Fig. 4.3 to support your answer. [3]

Answer 29

any 3 from:::::: -

positive correlation ;

more antibiotics used, more bacteria are resistant ;

variation between countries at each dosage ;

countries with antibiotic use of <1%, less than 10% bacteria are resistant ;

countries with antibiotic use of 3(+)%, more than 40% bacteria are resistant ;

Question 30

Many different antibiotics are used.
Suggest why some antibiotics are used less frequently than others. [3]

Answer 30

bacteria are resistant to some antibiotic ;

some are specific ;

some antibiotics used for rare disease(s) ;

some only used as last resort ;