Unit 2.

1. Match the words with their definitions.

   1.habitat	A. the act or process of producing offspring
   2.photosynthesis	B. a group of animals or plants whose members are similar and can breed together to produce young animals or plants
   3.excretion	C. something that helps a process to develop more quickly or more strongly
   4.reproduction	D. small amounts of water that are present in the air, in a substance, or on a surface
   5.species	E. the natural home of a plant or animal
   6.stimulus	F. the process of getting rid of waste material from your body
   7.response	G. the production by a green plant of special substances like sugar that it uses as food, caused by the action of sunlight on chlorophyll
   8.moisture	H. something that is done as a reaction to something that has happened or been said

2. Can you distinguish a living thing from non-living one? What criteria do you consider?

3. Read the text about peculiarities of living things. Living things

There are a vast number of living things in the world. These comprise animals, plants and microorganisms. Living things are often described as organisms.

Living things are found everywhere in the world — on land, in the air, in the sea and underground. Different organisms live in different places. The place where an organism lives is called its habitat. The habitat of a fly might be a greenhouse, a goldfish's habitat might be its tank or bowl. The Earth provides millions of different habitats — some hot, some cold, some dry, some wet. The conditions in a habitat make up the environment.

In general, living things prefer a moderate environment with warm temperatures, water and a supply of food.

The differences in physical factors, such as temperature, humidity and daylight hours, between localities are often reflected in the organisms found there. For example, animals which live in water often have streamlined bodies and those that live in very cold climates often have thick fur or layers of fat. We can sum this up by saying that many organisms are adapted to the habitat in which they live.

Characteristics of living things

There are thousands of different chemical reactions occurring in even the smallest animals and plants. These reactions are essential for life. If they stop, the organism dies. All the chemical processes in an organism are called its metabolism.

There are seven important characteristics or life processes common to all plants and animals.

They grow. Plants grow all their lives, but animals usually stop growing once they are adult. Even when growth stops, the materials in an animal's body are being replaced by substances from its food. In an adult human being, all the chemicals in the body are replaced over a period of seven years.

They feed. Organisms must feed in order to grow. Food is needed for growth, for energy and to replace worn-out parts. Animals and plants feed in different ways.

Plants take in simple substances like carbon dioxide and water. They use these simple substances to make more complex substances which can be used as food. In order to do this, plants need energy which they get from sunlight. This process of making food is called photosynthesis.

Animals eat plants or other animals. They then break down the complex chemicals in their food into simpler substances. These simpler substances are then used for growth or energy.

They need energy. Living things need energy to grow, to replace worn-out parts and to move. They get this energy from their food. The process of breaking down food and gaining energy is called respiration.

They get rid of waste products. Organisms are like factories. Materials are constantly being taken in and used to produce other materials. Some of the products are useless, others are poisonous. The waste products of metabolism must not be allowed to collect in an organism or they will poison it. So the organism must get rid of them — this process is called excretion.

They produce offspring. Organisms must produce offspring in order for the species to survive. This process is called reproduction. Usually reproduction involves the union of a male and a female of the same species. This is called sexual reproduction. Some organisms can reproduce on their own without needing both a male and a female. This is called asexual reproduction.

They move. Animals can move parts of their body or even their whole body from one place to another. Plants cannot move themselves from one place to another, but they can move parts of their structure. For example, leaves may turn towards the sunlight and roots may grow towards moisture.

They respond to stimuli. If someone tickles you, you will probably draw back. The tickling is a stimulus, your drawing back is a response. The main stimuli to which organisms respond are heat, light, sound, touch and chemicals which have tastes and smells. In general, plants respond to stimuli much more slowly than animals.