Population in Ecosystems

Question 1

Answer 1

• intraspecific competition
• compete with fertile males to mate

Question 2

describe how the mark-release-recapture method could be used to determine the population of A.aegypti at the start of the investigation?

Answer 2

• capture, mark and release
• leave time for mosquitoes to disperse before second sampling
• population size = no. caught in 1st sample x no. caught in 2nd sample / number marked in second sample

Question 3

the release of radiation-sterilised A.aegypti has not been very successful in controlling the transmission of dengue.

suggest why?

Answer 3

radiation affects attractiveness of A.aegypti

Question 4

suggest why the scientists released more transgenic males every week?

Answer 4

• maintain competition
• as more transgenic males die

Question 5

the release of transgenic males proved successful in reducing the number of A.aegypti.

describe how the results in the figure support this conclusion?

Answer 5

number lower after 12 weeks

Question 6

during the dry season the protein content of plants decreases

suggest one way in which lack of rain could account for this change

Answer 6

• less nitrate taken up
• less protein synthesis

Question 7

throughout the year the mean protein content of all plants which could be eaten and the mean protein content of food actually eaten differs

suggest one explanation for this difference

Answer 7

• not all plant eaten (roots)
• part of plant with high/low protein content

Question 8

when wildebeest eat food containing less than 6% protein, they start to lose protein from their body tissues

suggest and explain how a deficiency of one named protein makes the wildebeest susceptible to being caugh by predators

Answer 8

• myosin /actin
• muscles - weak