EKFC Biology B - Unit 4: Evolution

Bacteria will grow wherever they have adequate food and a suitable temperature. Nutrient agar is a gel-like substance similar to Jell-O that is often used for growing bacteria in Petri dishes. Students swabbed different areas of the school and then rubbed the swab onto a Petri dish with nutrient agar.

Which of the following questions do the results below best answer?

• Is more bacteria found on door handles that are used more often?

• Are bacteria transferred from one door to another?

• Does cleaning a door handle with Lysol wipes eliminate 99.9% of bacteria?

• Which types of bacteria are found on door handles?

Antibiotics are chemicals that kill bacteria. Students conducted an experiment to see how well the antibiotic Ampicillin kills bacteria in a Petri dish. They put a paper disk that had been soaked in Ampicillin onto a Petri dish smeared with bacteria.

The antibiotic soaked into the gel and killed most of the bacteria around the disk. However, the students were surprised to see that some bacteria survived (the dots near the disk in the picture). What explains how this could happen?

• Some of the bacteria in the population had variations in their DNA that made them resistant to the antibiotic.

• The bacteria nearest the antibiotic disk became immune to it because they were exposed to the strongest dose.

• The bacteria got used to the antibiotic over time so it stopped working as well and some bacteria began to grow near the disk.

• A few of the bacteria adapted to the presence of the antibiotic in order to survive.

The students decided to pick up the bacteria growing near the antibiotic disk with a sterile swab and transfer them to a new Petri dish. They spread the bacteria evenly over the plate and placed a new antibiotic disk on top.

What conclusion is best supported by the results from experiments 1 & 2?

• The antibiotic worked better in experiment 2 than in experiment 1.

• The zone of inhibition is smaller in experiment 2, which means that the bacteria are less resistant to the antibiotic than in experiment 1.

• The bacteria in experiment 2 are immune to the antibiotic because they were exposed to it in experiment 1.

• The antibiotic was less effective in experiment 2 because the proportion of resistant bacteria in the population is higher than in experiment 1.

Below is a graph of an infection with 1,000,000 bacteria. The patient was given multiple doses of an antibiotic to kill the bacteria. Each dose was 99.9% effective and doses were given every 4 hours for 24 hours. Between each dose, the remaining bacteria divided every 20 minutes.

Refer to the graph above. What type of growth does the bacteria display after each antibiotic dose is given?

• exponential growth

• exponential decay

• linear growth

• linear decay

Below is a graph of an infection with 1,000,000 bacteria. The patient was given multiple doses of an antibiotic to kill the bacteria. Each dose was 99.9% effective and doses were given every 4 hours for 24 hours. Between each dose, the remaining bacteria divided every 20 minutes.

Refer to the graph above. How many doses of antibiotics were given?

• 2 doses

• 4 doses

• 6 doses

• 8 doses

Below is a graph of an infection with 1,000,000 bacteria. The patient was given multiple doses of an antibiotic to kill the bacteria. Each dose was 99.9% effective and doses were given every 4 hours for 24 hours. Between each dose, the remaining bacteria divided every 20 minutes.

If bacteria divide every 20 minutes, how many bacteria would there be after 2 hours if you started with just one?

• 12 bacteria

• 32 bacteria

• 64 bacteria

• 128 bacteria

Guppies are small fish found in streams in Venezuela. Male guppies vary in their coloration: some are brightly colored with reflective spots, while others are drab colors with few spots. Brighter colors attract females and allow guppies to have more offspring, but males cannot be too brightly colored or they will be seen and consumed by predators.

A typical natural population of guppies consists of hundreds of guppies. Which statement best describes the guppies of a single species in an isolated population?

• The guppies share all of the same characteristics and are identical to each other.

• The guppies share all of the essential characteristics of the species; the minor variations they display don’t affect survival.

• The guppies are all identical on the inside, but have many differences in appearance.

• The guppies share many essential characteristics, but also vary in many features.

Guppies are small fish found in streams in Venezuela. Male guppies vary in their coloration: some are brightly colored with reflective spots, while others are drab colors with few spots. Brighter colors attract females and allow guppies to have more offspring, but males cannot be too brightly colored or they will be seen and consumed by predators.

Assuming ideal conditions with abundant food and space and no predators, what would happen if a mating pair of guppies was placed in a large pond?

• The population would increase rapidly.

• The guppy population would stay about the same year after year.

• The population would stay small because guppies have only enough babies to replace themselves.

• The population would double and then stay relatively stable.

Guppies are small fish found in streams in Venezuela. Male guppies vary in their coloration: some are brightly colored with reflective spots, while others are drab colors with few spots. Brighter colors attract females and allow guppies to have more offspring, but males cannot be too brightly colored or they will be seen and consumed by predators.

Once a population of guppies has been established for a number of years in a real (not ideal) pond with other organisms including predators, what will likely happen to the population?

• The guppy population will likely stay about the same size year after year.

• The guppy population will continue to rapidly grow in size.

• The guppy population will gradually decrease until no more guppies are left.

• It is impossible to tell because populations do not follow patterns.

Guppies are small fish found in streams in Venezuela. Male guppies vary in their coloration: some are brightly colored with reflective spots, while others are drab colors with few spots. Brighter colors attract females and allow guppies to have more offspring, but males cannot be too brightly colored or they will be seen and consumed by predators.

Guppies eat mainly algae and tiny crustaceans called brine shrimp. Which statement best describes the availability of food for guppies in a stream?

• Finding food is never a problem since algae grows very quickly.

• Since guppies can eat plants or animals, there is likely to be enough food for all of the guppies at all times.

• Guppies can get by on very little food, so the food supply does not matter.

• It is likely that sometimes there is enough food, but at other times there is not enough food for all of the guppies.