Needs of Organisms 3.2 List factors that affect an area’s ability to support life. Protect how changes in the environment might affect organisms.

Needs of Organisms Organisms depend on their environment for everything they need in order to live. Every kind of organism has a different set of specific needs. Take five minutes to write a list of your “human” specific needs in order to survive:

Brainstorm - Class List of Specific Human Needs

Needs of Organism Water – the presence of fresh water is one of the most important factors in the ability of land to support life. Water is needed for plant to grow, and plants and water are both necessary for an animal population to survive. The amount of rainfall on an area of land directly affects the characteristics and abundance of life in that area.

Water Organisms that live in the oceans are not usually affected by local rainfall, but fish and other aquatic organisms are affected by water quality: temperature, nutrients, dissolved oxygen, other chemicals, and the kinds and numbers of organisms present affect water quality. Water that becomes warmer cannot contain as much oxygen as cooler water. As a result, some organisms will not be able to survive in warmer water.

Needs of Organism Food and Energy: Almost all the energy used by living things comes from the sun. Through photosynthesis, plants and algae make food by capturing energy from sunlight. Animals and other organisms get their energy by eating plants, or by eating other animals. Food contains not only energy, but also minerals, vitamins, and other chemicals. These materials are used by organisms to build tissue and carry out biochemical reactions. Together, all the substances that an organism requires from food are called nutrients.

Food and Energy Some substances are stored an can build up in cells of the body’s tissues. If a stored substance is harmful, the tissues can become poisonous if eaten by other organisms. DDT is a good example. (Homework)

Needs of Organisms Living Space: All organisms need space to live. Living space enables organisms to obtain the materials they need from the environment. For example: plants need space to receive enough sunlight. They also need space for their roots to grow to obtain water and minerals. If plants or trees grow to close together, some will die.

Living Space Animals need space in which to seek food, water, shelter, and mates. Many animals claim specific areas of their own. An area that is claimed as a living space by an individual animal or group of animals is called a territory. Territorial animals mark their territory with scents to let intruders know that the area has limits. The size of an animal’s territory is determined by the needs of that animal. If enough space is not available, animals will compete for a territory, often to the death.

Needs of Organisms Climate: The body temperature of most organisms is determined by the temperature of the environment. Most organisms can survive only within a certain range of temperatures. Many organisms, especially plants that live in colder areas, survive the cold by becoming dormant (the life processes within the body slow down). Like plants, many types of animals become dormant during periods of cold temperatures and low food supplies. Dormancy in some animals is called hibernation. (heart-rate and breathing slow down, body temperature drops, and the animal enters a sleeplike state).

Homework Computer Research Homework: List at least 3 organism’s affected by the chemical DDT. Provide a list of at least 5 animals and how they mark their territory.