Organisms and Populations Test - 4

Epiphytic plants hang in air, so they cannot absorb water from soil. The velamen of an orchid is many cell layers thick and capable of absorbing atmospheric moisture and nutrients. It also protects the underlying cells against damaging UV rays. It is an important adaptation of epiphytic orchids.

The Raunkiaer system is a system for categorizing plants using life-form categories, devised by Danish botanist Christen C. Raunkiaer. Raunkiaer's life-form system may be useful in researching the transformations of biotas and the genesis of some groups of phytophagous animals.

The type of symbiosis hermit crab and sea anemone engage in is called commensalism. Commensalism means one organism benefits and the other organism isn't harmed by the partnership. Neither the hermit crab nor the sea anemone is negatively affected by their symbiotic and commensalistic relationship.

A and E are not the features of hydrophytes.

Fluctuations in natural population are affected by: birth and death rates, resources like food, water and space, natural calamities such as earthquake and volcanic eruptions, abiotic factors like temperature and rainfall, other organisms sharing habitat.

Mesothermic plants live in neither hot nor cold climates as in tropical rain forests.
Heliothermic plants grow in alpine regions.
Eurythermic plants are those which grow in a wide range of temperature, from 0 to 55°C.
Stenothermic plants live in a narrow range of temperature.

In a saturated air mass, if the prevailing lapse rate is less than its wet adiabatic lapse rate, the atmosphere is said to be in stable equilibrium. If the environmental lapse rate is less than the moist adiabatic lapse rate, the air is absolutely stable - rising air will cool faster than the surrounding air and lose buoyancy. This often happens in the early morning, when the air near the ground has cooled overnight. Cloud formation in stable air is unlikely.

Agricultural revolution has helped mankind with new varieties of plants and biofertilisers. Industrial revolution has given us lots of job opportunities and increased the per capita income. Medical advances have increased our life span. Man is helping the society through his altruistic approach (to help others).

Savannahs have warm temperature year round. There are actually two very different seasons in a savannah; a very long dry season (winter) and a very wet season (summer).

Biomes are climatically and geographically defined as similar climatic conditions on Earth, such as communities of plants, animals and soil organisms. Biomes are defined by factors, such as plant structures (such as trees, shrubs and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland and savanna) and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic or historical similarities.