What is a tree line?
Tree line is the edge of the habitat where trees are capable of growing. Due to environmental conditions such as cold temperature, high altitude or lack of moisture the trees are not found beyond this line and if found show stunted growth or form low dense matted bushes.
$$ \text { Define 'zero population growth rate'. Draw a age pyramid for the same. } $$
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 |