Monitoring and maintaining health

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Question 16

Medium

Antibiotics and antiseptics are both used to control pathogen populations to maintain human health. Which is a correct statement comparing antibiotics and antiseptics?

Option 1: Antibiotics can be taken internally to treat bacterial infections, whereas antiseptics are applied topically to living tissue.
Option 2: Antiseptics are highly targeted to destroy specific bacterial metabolic pathways, while antibiotics destroy all living tissues non-specifically.
Option 3: Both antibiotics and antiseptics can be safely injected into the bloodstream in high concentrations to treat systemic infections.
Option 4: Antiseptics are only used to sterilise non-living laboratory equipment, whereas antibiotics are used exclusively on external skin surfaces.

[1]

Researchers conduct an investigation to compare the antimicrobial properties of three plant extracts ( $A$ , $B$ , and $C$ ) against a particular strain of bacterium. This is the method they use:

Inoculate a sterile agar plate with a liquid culture of the bacterium.
Soak three sterile filter paper discs, each in a different plant extract ( $A$ , $B$ , and $C$ ).
Place the discs onto the agar surface using sterile forceps.
Tape the lid of the Petri dish and incubate.

(i) Describe how the researchers should prepare and inoculate the agar plate to ensure aseptic conditions.

[2]

The researchers are instructed to tape the lid of the Petri dish with two small pieces of tape rather than sealing it completely around the circumference. Explain the biological reason for this.

[2]

The diagram shows the Petri dish after 48 hours of incubation.

Petri dish showing zones of inhibition around discs A, B, and C

(i) State two conclusions that can be drawn from these results regarding the efficacy of plant extracts $A$ , $B$ , and $C$ .

[2]

Another researcher tests a fourth plant extract, $D$ . Extract $D$ is so potent that its zone of inhibition completely clears the entire Petri dish, matching the result obtained with extract $B$ at full strength. Explain how the researchers could modify their experiment to determine which plant extract, $B$ or $D$ , is more effective.

[2]

Monitoring and maintaining health

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

Question 16

Medium

Antibiotics and antiseptics are both used to control pathogen populations to maintain human health. Which is a correct statement comparing antibiotics and antiseptics?

Option 1: Antibiotics can be taken internally to treat bacterial infections, whereas antiseptics are applied topically to living tissue.
Option 2: Antiseptics are highly targeted to destroy specific bacterial metabolic pathways, while antibiotics destroy all living tissues non-specifically.
Option 3: Both antibiotics and antiseptics can be safely injected into the bloodstream in high concentrations to treat systemic infections.
Option 4: Antiseptics are only used to sterilise non-living laboratory equipment, whereas antibiotics are used exclusively on external skin surfaces.

[1]

Researchers conduct an investigation to compare the antimicrobial properties of three plant extracts ( $A$ , $B$ , and $C$ ) against a particular strain of bacterium. This is the method they use:

Inoculate a sterile agar plate with a liquid culture of the bacterium.
Soak three sterile filter paper discs, each in a different plant extract ( $A$ , $B$ , and $C$ ).
Place the discs onto the agar surface using sterile forceps.
Tape the lid of the Petri dish and incubate.

(i) Describe how the researchers should prepare and inoculate the agar plate to ensure aseptic conditions.

[2]

The researchers are instructed to tape the lid of the Petri dish with two small pieces of tape rather than sealing it completely around the circumference. Explain the biological reason for this.

[2]

The diagram shows the Petri dish after 48 hours of incubation.

Petri dish showing zones of inhibition around discs A, B, and C

(i) State two conclusions that can be drawn from these results regarding the efficacy of plant extracts $A$ , $B$ , and $C$ .

[2]

Monitoring and maintaining health

Question 16

Monitoring and maintaining health Questions

Monitoring and maintaining health

Question 16

Monitoring and maintaining health Questions