Photosynthesis – Food Chain
What do plants and animals need to grow?
Almost all plants and animals need air, water, light, and nutrition to grow. Green plants use a complicated chemical process, called photosynthesis, to create energy to survive and grow. Since plants create their own energy, they are the first link in the food chain. Animals need to drink water and eat plants or other animals for energy. Therefore, they are present in the next step of the food chain. There are some animals, like camels, that can survive for days without drinking water. Since they live in deserts with very little water, they have adapted to the special conditions of their habitat.
How do plants get food?
Unlike animals, plants make their own food and, except for a few carnivorous plants, do not eat other organisms. Green plants use water, nutrients and a green material in their leaves called ‘chlorophyll’ to make their food. Normally water and nutrients are absorbed from the soil through their roots. Some plants, however, have developed other methods of obtaining water and nutrients. Many plants make funnel-shaped ‘containers’ with their leaves to collect water. Carnivorous plants use their digestive juices to convert insects caught in their collapsible or sticky traps into nutrients.
What happens when we keep plants in the dark?
In the absence of light, plants lose their leaves and die, leaving only their roots and stems. The plants grow slowly at night and in winters. Most animals also depend on light, although some have adapted to their dark habitats. For example, moles that live underground are nearly blind because they don’t need their eyes underground. Humans also need sunlight to help make vitamin D in our skin, which in turn is needed to build bone. We will also lose time if it is very dark around us for a long time.
What is photosynthesis?
The chloroplast inside the green leaves of plants is the ‘workshop’ where photosynthesis takes place. The roots supply the leaves with water, and carbon dioxide is absorbed from the air through tiny pores on the underside of the leaf. They both break down into the elements hydrogen, carbon, and oxygen with the help of chlorophyll and sunlight. Plants build ‘glucose’ (grape sugar) from these elements and oxygen is released into the atmosphere as a by-product. Photosynthesis has been the source of oxygen in the air since the origin of life on Earth.
How do camels survive long journeys in the desert?
Camels can get by for about two weeks without drinking water because they can store up to 150 liters of water in their bodies. Fat is also stored in their humps and this energy reserve can sustain them for about 30 days without eating. Also, unlike most other mammals, camels can change their body temperature. At night they lower their body temperature considerably so that during the day the body warms up slowly and they do not sweat much. Consequently, there is no fluid loss early in the day.
What is the food chain?
In nature, there are ‘producers’ who build the biological mass and ‘consumers’ who eat. Producers are plants, which grow and create energy with the help of photosynthesis. They are consumed by a consumer, and that consumer is often consumed by another consumer. This chain of consumers is called the ‘food chain’. A short food chain is grass-cow-man. A longer one is algae-water flea-herring-seal-polar bear: one water flea eats algae, one herring eats many water fleas, one seal eats herring, and the polar bear eats the seal. Ultimately, it takes a lot of algae to feed a polar bear. When the polar bear dies, other animals eat its meat or bacteria break it down into nutrients. These nutrients are again used by the algae to create energy, thus completing the food chain.
