Question

time elapsed (hours)
these pictures show the petri dish of bacteria at three points in time.

hour 14.5 hour 15 hour 17

which of the following are the most likely reasons that the population of bacteria stopped growing? select two.

the population ran out of space.
the population reached an optimal size and decided to stop growing.
individuals couldnt find mates to reproduce.
the population used up its supply of food.

Explanation:

To determine why the bacteria population stopped growing, we analyze each option:

1. "The population ran out of space": In a Petri dish, limited space (as the bacteria spread and fill the dish) restricts further growth. This is a valid limiting factor for bacterial populations in a confined environment.
2. "The population reached an optimal size and decided to stop growing": Bacteria do not "decide" to stop growing; growth is driven by environmental factors, not conscious decisions. Eliminate this.
3. "Individuals couldn’t find mates to reproduce": Bacteria reproduce asexually (e.g., binary fission), so mating is not required. Eliminate this.
4. "The population used up its supply of food": Nutrient depletion (food running out) is a common limiting factor for bacterial growth in a closed system like a Petri dish. This is valid.

So the two most likely reasons are the population running out of space and using up its food supply.

Answer:

• The population ran out of space.
• The population used up its supply of food.