A sedentary sea anemone gets attached to the shell lining of a hermit crab. The association is:
1. Symbiosis
2. Commensalism
3. Amensalism
4. Ectoparasitism
A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is:
1. 15
2. 05
3. zero
4. 10
According to Darwin, organic evolution is due to:
1. | Interspecific competition. |
2. | Competition within closely related species. |
3. | Reduced feeding efficiency in one species due to the presence of interfering species. |
4. | Intraspecific competition. |
People who have migrated from the planes to an area adjoining Rohtang Pass about six months back:
1. | Have more RBCs and their haemoglobin has a lower binding affinity to 02 |
2. | Are not physically fit to play games like football |
3. | Suffer from altitude sickness with symptoms like nausea, fatigue, etc. |
4. | have the usual RBC count but their haemoglobin has a very binding affinity to 02 |
What type of human population is represented by the following age pyramid?
1. | Human foetus developing inside the uterus draws nourishment from the mother |
2. | Head louse living on the human scalp as well as laying eggs on human hair |
3. | The cuckoo (koel) lays its eggs in a crow's nest |
4. | The female Anopheles bites and sucks blood from humans |
Study the four statements (a–d) given below and select the two correct ones out of them:
a: | A lion eating a deer and a sparrow feeding on grain are ecologically similar in being consumers |
b: | Predator starfish Pisaster helps in maintaining species diversity of some invertebrates |
c: | Predators ultimately lead to the extinction of prey species |
d: | Production of chemicals such as nicotine and strychnine by plants is metabolic disorder |
The two correct statements are:
1. a and d
2. a and b
3. b and c
4. c and d
A country with a high rate of population growth took measures to reduce it. The figure below shows age-sex pyramids of populations. A and B are twenty years apart. Select the correct interpretation about them:
Interpretations
1. | 'A' is more recent and shows a slight reduction in the growth rate |
2. | 'B' is an earlier pyramid and shows stabilised growth rate |
3. | 'B' is more recent showing that the population is very young |
4. | 'A' is the earlier pyramid and no change has occurred in the growth rate |
The table below gives the populations(in thousands) of ten species(A--J) in four areas (a-d) consisting of the number of habitats given within brackets against each. Study the table and answer the question as follows:
which area out of a to d shows maximum species diversity?
1. b
2. c
3. a
4. d
The population of an insect species shows an explosive increase in numbers during the rainy season followed by its disappearance at the end of the season. What does this show?
1. | S-shaped or sigmoid growth of this insect |
2. | the food plants mature and die at the end of the rainy season |
3. | Its population growth curve is of J-type |
4. | The population of its predators increases enormously |