Question

extension questions

1. for the past 10 to 25 years, farmers have planted crop seeds that have been genetically modified to withstand treatment with a common weed killer called roundup®. this allows the farmers to spray their fields to get rid of weeds without harming their crops. recently, more and more farmers have discovered that their fields have roundup-resistant pigweed growing along with their crop. use what youve learned in this activity to explain how this came about.

1. many popular products from hand soap to clothing advertise that they have antibacterial qualities. most microbiologists recommend against their routine use in our daily lives. how can you explain this using your knowledge from this activity?

Explanation:

For Question 22:

1. Pigweed populations have genetic variation naturally; some individuals have random mutations that make them less susceptible to Roundup.
2. When farmers repeatedly spray Roundup, it acts as a selective pressure: most non-resistant pigweed is killed, but the resistant mutants survive.
3. The surviving resistant pigweed reproduce, passing on their resistance traits to offspring. Over many generations, the proportion of Roundup-resistant pigweed in the field increases until it is widespread.

For Question 23:

1. Bacterial populations have natural genetic variation, including some individuals with mutations that make them resistant to antibacterial agents.
2. Routine, frequent use of antibacterial products creates constant selective pressure: most non-resistant bacteria are killed, but resistant mutants survive and reproduce.
3. Over time, resistant bacterial populations grow, and resistant traits can spread between bacteria. This reduces the effectiveness of antibacterial products and increases the risk of infections caused by drug-resistant bacteria that are harder to treat.

Answer:

Question 22:

Roundup-resistant pigweed evolved through natural selection:

1. Random mutations created rare pigweed with Roundup resistance.
2. Roundup spray killed non-resistant pigweed, leaving resistant individuals to survive and reproduce.
3. Over generations, resistant pigweed became dominant in fields.

Question 23:

Routine use of antibacterial products is not recommended because:

1. It creates selective pressure that favors the survival and reproduction of bacteria with natural mutations for antibacterial resistance.
2. This leads to the growth of resistant bacterial populations, reduces the products' effectiveness over time, and increases the risk of hard-to-treat resistant bacterial infections.