Imagine that you have created a fusion between the Trp operon, which encodes the enzymes for tryptophan biosynthesis, and the Lac operon, which encodes the enzymes necessary for lactose utilization. Under which set of conditions (A–F below) will β-galactosidase be expressed in the strain that carries the fused operon?

A. Only when lactose and glucose are both absent.

B. Only when lactose and glucose are both present.

C. Only when lactose is absent and glucose is present.

D. Only when lactose is present and glucose is absent.

E. Only when tryptophan is absent.

F. Only when tryptophan is present.

TLS Online TPP Program

#Question id: 10824

#Unit 10. Ecological Principles

Interspecific competition has been demonstrated experimentally in

TLS Online TPP Program

#Question id: 12640

#Unit 10. Ecological Principles

Plant species produce a which type of  defensive proteins that bind to carbohydrates or carbohydrate-containing proteins. After being ingested by an herbivore, that bind to the epithelial cells lining the digestive tract and interfere with nutrient absorption

TLS Online TPP Program

#Question id: 12257

#Unit 10. Ecological Principles

Which of the following is most likely to reduce competition in sympatric, closely related species? 

TLS Online TPP Program

#Question id: 12256

#Unit 10. Ecological Principles

Ant species X preys upon ant species Y. A researcher has the following set of observations regarding the behaviour of species X where aggression signifies a predatory response.

Which of the following statement(s) are correct regarding the behaviour of Species X?

(i)    A glass bead is sufficient to elicit the predatory response.

(ii)   Both chemical and non-chemical cues are involved in the predatory response.

(iii)  Chemical cues are necessary to elicit the predatory response.

(iv) Chemical cues are sufficient to elicit the predatory response

TLS Online TPP Program

#Question id: 12255

#Unit 10. Ecological Principles

The following three panels show the change in population size over time for two species when they are found alone and when they are found together. Which kind of interaction best describes the relationship between the two species?

TLS Online TPP Program

#Question id: 12254

#Unit 10. Ecological Principles

Assume that the abundance of a species in a community is proportional to the size of its niche. As each new species colonises this community, an existing niche is split. The resultant relative abundances of species in this community will be most uneven