$$ \text { Define 'zero population growth rate'. Draw a age pyramid for the same. } $$
When the pre-reproductive age group individuals are comparatively fewer and both reproductive and post-reproductive stages are almost in equal stage, i.e., at same level. It is zero population growth rate.
An inverted bell shaped age pyramid is obtained for zero population growth rate.
List any four characters that are employed in human population census.
A population has the following characterstics that are employed in human population census.
(i) Natality and mortality
(ii) Sex ratio
(iii) Population density
(iv) Age distribution
(v) Population growth
Give one example for each of the following types
(a) Migratory animal
(b) Camouflaged animal
(c) Predator animal
(d) Biological control agent
(e) Phytophagous animal
(f) Chemical defense agent
(a) Migratory animal-American buffalo and dolphin.
(b) Camouflaged animal-Grasshopper and chameleon.
(c) Predatoranimal-Lion.
(d) Biological control agent-Myxoma virus to kill European rabbit and Gambusia fish to check growth of mosquito larvae.
(e) Phytophagous animal-Insects (beetle, butterfly, etc.).
(f) Chemical defense agent-Cardiac glycosides.
$$ \text { Fill in the blanks } $$
| Species A | Species B | Type of Interaction | Example |
|---|---|---|---|
| + | - | __ | __ |
| + | + | __ | __ |
| + | __ | Commensalism | __ |
| Species A | Species B | Type of Interaction | Example |
|---|---|---|---|
| + | - | Predation | Phytophagous animal and plants. |
| + | + | Protocoperation | Oxpecker and black rhino |
| + | - | Comensalism | Sea anemone and Hermit crab |
Observe the set of 4 figures $\mathrm{A}, \mathrm{B}, \mathrm{C}$ and D and answer the following questions.
I. Which one of the figures shows mutualism?
II. What kind of association is shown in D?
III. Name the organisms and the association in C.
IV. What role is the insect performing in $B$ ?
I. Figure A show a pollinator (bee) on a flower. The association between pollinator insect and plant is termed as mutulalism.
II. Predation.
III. Egrets and grazing cattle is good example of commensalism.
IV. Scavenging- The insect is playing the role of an scavenger.