Tag: level of biological organization in animals

An open system is defined as a system wherein there is free exchange of both matter and energy with the surroundings. The system has interaction with the external environment. A close system is defined as a system where there is no exchange of either matter or energy with the surroundings. All the ecosystems on Earth are called as open systems. Earth is an open system for energy. 

The living world is made up of different communities living in it. Some of these communities are the communities living in oceans, fresh water and forest communities, communities living in grasslands and deserts. These communities have different individuals belonging to them and have certain different characteristics. So, option D is the correct answer.

An incomplete ecosystem is cave. Its habitat is not suitable for primary productivity. It lacks sunlight and primary plant productivity. The animals and plants are present only at the entrance of cave as limited sunlight reaches at the entrance.

An ecosystem consists of biotic and abiotic components. Biotic components or living things include animals, plants, microorganisms. Abiotic components or nonliving things include air, soil, temperature. It is of two types, natural ecosystem and artificial or man made ecosystem. Examples of natural ecosystem include forest, aquatic ecosystem. Examples of man made ecosystem includes aquarium, zoo, botanical garden. In man made ecosystem, the plants and animals grow or survive outside their natural habitat in an artificial environment.

• A biome is a group of ecosystems with similar climates and organisms.
• There are five major biomes in the world. They are the forest, desert, grassland, aquatic and altitudinal biomes.
  
• Hence Combined ecosystem forms Biomes.
• So, the correct answer is 'Biomes'.

Gene flow is the passing over of genes from one population to another population. There are a various factors that affect the gene flow. The largest unit of population in which gene flow is readily possible is biological species. In species, successful interbreeding is possible which results in the successful reproduction and hence the gene flow.