- Another well known example of mutualism is furnished by the bacteria of the genus 5KL]RELXP. These bacteria form nodules
on the roots of leguminous plants and obtain carbohydrates and other substances from the plants. In return, the bacteria
fix the gaseous nitrogen and pass it on to the host. (J, root nodules of legumes alder and &DVXDULQD.
- Protocooperation
- In this association, two organisms are mutually benefitted by each other but the association is non-obligatory, LH, not
necessary for their existence.
- (J, Cattle egret (%XEXOFXVLELV) feeds on lice and ticks of cattle, crocodile bird (3OXYLDQXVDHJ\SWLXV) rids crocodile of leeches
sticking inside its mouth while shrimp eats up the parasites on the body of fish.
Table: Types of biotic interactions
Interaction Species A Species B Nature of interaction
(i) With positive effect
Mutualism
Protocooperation
Commensalism
+
+
+
+
+
zero
Beneficial to both, obligatory
Beneficial to both, not obligatory
Commensal benefitted, other unaffected
(ii) With negative effect
Parasitism
Predator
Competition
Amensalism
+
+
zero
Parasite (usually small) benefitted, host harmed
Predator (generally larger) kills and feeds on prey
Mutual inhibition in direct competition and due to short
supply of resources in indirect competition
One inhibited, other unaffected
- Bell-shaped age pyramid is possible when
(a) post-reproductive individuals are more than
reproductive individuals
(b) pre-reproductive individuals are almost equal to
reproductive individuals
(c) reproductive individuals are more than pre-
reproductive individuals
(d) pre-reproductive individuals are almost equal to
post-reproductive individuals.
- Which among the following is an example of behavioural
adaptation?
(a) Altitude sickness on going to high altitude.
(b) Excretion of concentrated urine by camels.
(c) Developing ice nucleating proteins in extracellular
spaces in body.
(d) Desert lizards living in burrows to escape from heat.
- The type of interaction present between sucker fish and
shark is
(a) protocooperation (b) parasitism
(c) commensalism (d) mutualism.
4. Which of the following best describes Rensch’s rule?
(a) Extremities of mammals of colder regions are shorter
than those of warmer regions.
(b) Fish of cold water level tend to have more vertebrae.
(c) Birds of colder areas have narrow wings as compared
to those of warmer areas.
(d) Warm blooded animals of colder areas are of larger
size as compared to those of warmer areas.
5. An ecological component of habitat which is delimited by
functioning of an organism is
(a) habitat (b) guild
(c) environment (d) niche.
6. An example of vesperal organism is
(a) butterfly (b) rabbit
(c) rat (d) %XEDOFXV.
7. Which horizon of soil profile is saturated with moisture and
represents the water table?
(a) O-horizon (b) A-horizon
(c) B-horizon (d) C-horizon
