In some sheep, the presence of beard is produced by an autosomal allele that is dominant in males and recessive in females. A beard female is crossed with a homozygous beardless male. One of the resulting F1 females is crossed with a beardless male. What proportion of the male and female progeny from this cross will have beard in F2 generation?

TLS Online TPP Program

#Question id: 12426

#Unit 10. Ecological Principles

In an ecosystem, fixed carbon has accumulated in the form of organic matter derived from dead plants and animals. Which of the following is the best explanation for this observation? 

TLS Online TPP Program

#Question id: 12427

#Unit 10. Ecological Principles

Trophic efficiency is

TLS Online TPP Program

#Question id: 12428

#Unit 10. Ecological Principles

Flycatcher birds that migrate from Africa to Europe feed their nestlings mostly with moth caterpillars. The data presented show the mean dates of egg laying, hatching, and fledging of flycatcher young, and the 1980 and 2000 peak mass of caterpillars.

Why are ecologists  concerned about the shift in  date from May 28 in  1980 to May 15 in  2000 of the caterpillar peak mass?

TLS Online TPP Program

#Question id: 12429

#Unit 10. Ecological Principles

Flycatcher birds that migrate from Africa to Europe feed their nestlings mostly with moth caterpillars. The data presented show the mean dates of egg laying, hatching, and fledging of flycatcher young, and the 1980 and 2000 peak mass of caterpillars.

Which of the following organisms is incorrectly paired with its trophic level? 

TLS Online TPP Program

#Question id: 12430

#Unit 10. Ecological Principles

Which of these ecosystems has the lowest net primary production per square meter?

TLS Online TPP Program

#Question id: 12431

#Unit 10. Ecological Principles

Nitrifying bacteria participate in the nitrogen cycle mainly by