The impact of immigration on population density is:

1.	Negative
2.	Both positive and negative
3.	Neutralized by natality
4.	Positive

Which one of the following is most appropriately defined:

The logistic population growth is expressed by the equation:

1. $\frac{dN}{dt}=rN\left(\frac{N-K}{N}\right)$

2. $\frac{dt}{dN}=Nr\left(\frac{K-N}{K}\right)$

3. $\frac{dN}{dt}=rN\left(\frac{K-N}{K}\right)$

4. $\frac{dN}{dt}=rN$

Match the items in Column-I with those in Column-II:

Select the correct option from the following:

A male insect mistakes an orchid flower to be female due to its shape and performs the act of copulation and induces pollination. This is an example of:
1.  Mimicry
2.  Pseudocopulation
3.  Pseudopollination
4.  None

Two different species cannot live for a long duration in the same niche or habitat. This is:

1. Allen's law

2. Gloger's rule

3. Competitive exclusion principle

4. Weismann's theory

Which of the following is a correct pair: 

1. Cuscuta – parasite

2. Dischidia – insectivorous

3. Opuntia – predator

4. Capsella – hydrophyte

Mycorrhiza is an example of:

1. Symbiotic relationship

2. Ectoparasitism

3. Endoparasitism

4. Decomposers

Inspite of interspecific competition in nature, which mechanism the competing species might have evolved for their survival?

Amensalism can be represented as:

1. Species A (–) : Species B (–)

2. Species A (+) : Species B (0)

3. Species A (–) : Species B (0)

4. Species A (+) : Species B (+)