Ecosystem Nutrition and Energy Flow

Plant mushroom get its food from dead and decaying plants. In short, they are saprophytes. Plants are green because they contain chlorophyll, which helps them with photosynthesis, the process of turning sunlight into food. Mushrooms are not green and they contain no chlorophyll. Therefore, they cannot photosynthesize. Mushrooms obtain their food by metabolizing dead or decaying organic matter, such as dead plants on the ground. Tiny filaments called as hyphae absorb the nutrients from the dead matter. Mushrooms are made up of hyphae filaments and a mass of hyphae is called as a mycelium. This is why, you often see mushrooms growing on dead tree stumps.

 The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs. The continual input of energy, mostly from sunlight, sustains the process of life. Sunlight allows plants, algae and cyanobacteria to use photosynthesis to convert carbon dioxide and water into organic compounds like carbohydrates. This process is the fundamental source of organic material in the biosphere. The overall productivity of an ecosystem is controlled by the total energy available.

The fundamental source of energy in almost all ecosystems is radiant energy from the sun. The energy of sunlight is used by the ecosystem's autotrophic, or self-sustaining, organisms. Consisting largely of green vegetation, these organisms are capable of photosynthesis - i.e., they can use the energy of sunlight to convert carbon dioxide and water into simple, energy-rich carbohydrates. The autotrophs use the energy stored within the simple carbohydrates to produce the more complex organic compounds, such as proteins, lipids, and starches, that maintain the organism's life processes. Organic matter generated by autotrophs directly or indirectly sustains heterotrophic organisms. Heterotrophs are the consumers of the ecosystem; they cannot make their own food. 

Human beings (Homo sapiens) are omnivores. People eat plants, such as vegetables and fruits. We eat animals, cooked as meat or used for products like milk or eggs. We eat fungi such as mushrooms. We also eat algae in the form of edible seaweeds such as nori, which are used to wrap sushi rolls, and sea lettuce is eaten in salads. Bears are omnivores, too. They eat plants like berries as well as mushroom (fungi) and animals like salmon or deer.

For all organisms, the sun, or solar radiation, is the ultimate source of energy. Plants are primary producers of energy from the sun. Plants use sun, chlorophyll, water, carbon dioxide and nutrients to manufacture glucose, an alternate form of energy. 

The answer is option A "It can carry out photosynthesis"
Because organisms that carry out photosynthesis to make their own food are called autotrophic. Algae contain chlorophyll pigments which helps them to trap energy from sunlight to form glucose (food) on their own.
While option B represents a feature of heterotrophs and option C for carnivores that eat insects.

According to the given paragraph. P and Q show mutual relationship, i.e. if Q will extinct then it will lead to extinction of Pas well and vice versa. If animal S is hunted to extinction, then population of animal R will start increasing abnormally in the absence of its predator. This uncontrolled growing population of R will feed more on Q population which may ultimately lead to Its extinction with time. As both P and Q depend on each other for existence hence, P population will start decreasing and ultimately get extinct with time.

When a plant shows some growth movement in response to a stimulus, it is known as tropism. Tropism is direction specific and depends on the direction of stimulus. Plants may either show positive or negative movement as a response to a stimulus. If the movement is towards the direction of stimuli, it is known as positive tropism while movement away from stimuli is known as negative tropism. Answer is true.

Holozoic nutrition involves the ingestion of complex organic substances, such as solid or liquid food particles, which are then digested internally.

Holo-whole and zoic means animals so animal that eats their food completely in the form of a liquid or solid and process it inside the body. The food particle is ingested and then enzymes act on it to digest it. It includes five steps ingestion, digestion, absorption, assimilation and excretion and most of the animals practice this type of nutrition including humans.

Amoeba obtains the food through phagocytosis process. Since, Amoeba has no mouth, it takes the food into it's body by means of pseudopodia, which completely enclose the particle of food, that is enveloped in vacuoles. Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel the organism's activities. In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction. Meiosis is a process of cell division in eukaryotes characterized by: two consecutive divisions: meiosis I and meiosis II. 

Holozoic nutrition is the process of taking in solid or liquid organic food, which is then digested and absorbed by the organism.