Environments and Organisms Test Review

Transcription

1 Environments and Organisms Test Review

2 Environments Key Concept 1: Environments have specific physical characteristics that provide food, water, air, or protection to populations and communities in an ecosystem. Every environment (an organism s surroundings) is a result of a delicate balance of living elements (organisms) and nonliving elements (objects, landforms, weather, and climate). An ecosystem is a community of living and nonliving things in their natural environment. In order for any population (living things that belong to the same group in the same area) or a community (group of different populations sharing an environment) to survive (stay alive), the living and nonliving elements must provide basic needs: food, water, air, and protection.

3 Environments Key Concept 2: Changes to an environment can affect whether certain organisms can survive in that ecosystem.

4 Environments For example, a forest fire clears dead plants to allow new plants to grow. Key Concept 3: Environmental changes, such as floods, droughts, or fires, will cause some organisms to perish or move, while permitting other organisms to thrive.

5 Food Chains Key Concept 1: Energy that moves through a food chain originally comes from the Sun. A food chain is the path of food energy that comes from the Sun is and passed on to organisms in an ecosystem. The energy that is transferred in the food chain begins with the Sun, which gives off heat and light energy.

6 Key Concept 2: Plants get their energy from the Sun and animals get their energy from plants and other organisms. In the illustration below, the energy that plants absorb from the Sun is passed on to plant-eating animals, such as the grasshopper. Some of the energy stored in the grasshopper is passed on to meat-eating animals, such as the frog. Then, the snake eats the frog. Finally, the small amount of energy left is passed on to the last meat-eating animal when the hawk eats the snake. Food Chains

7 Food Chains Key Concept 3: Removal of an organism from a food chain can affect other organisms. For example, imagine a food chain in which all the snakes in an area are killed or removed. There will be fewer predators eating the field mice and the field mice population will increase. If there are no snakes, the eagles might have a smaller food supply and the number of eagles may dwindle. If a fire destroys the shrubs, there will be fewer insects in the shrubs for the frogs to eat and so on. If any population of organisms changes in some way, either increasing or decreasing, it will affect other organisms in the community.

8 Changes in the ecosystem impact the whole ecosystem.

9 If frogs are removed from a pond, the insect population will increase due to lack of insect predators. However, the plants that the insects eat will begin to decrease due to an increased number of insects. The animals that feed on the frogs, such as snakes or other meat eaters, will be endangered.

10 Adaptations Key Concept 1: The structures of plants and animals are adapted to particular environments. An adaptation is a physical or behavioral characteristic that helps an animal or plant survive in its environment. Some organisms are better suited for some environments than others, and for any organism in any environment, it must adapt to survive.

11 Adaptations Key Concept 2: Structures of some animals, such as the blubber of seals or the fur of rabbits, help some animals survive in cold weather conditions. Structures are how the parts are put together on a plant or animal. Because mammals living in cold climates have to conserve body heat, they need structures that will keep their bodies warm. Seals, whales, and polar bears have blubber as an extra layer of fat under their skin that helps them insulate their bodies to adapt to freezing water temperatures. The double-layered fur on Arctic hares and polar bears are examples of cold climate adaptations that help animals insulate warm air trapped among the dense hairs in their fur.

12 Adaptations Key Concept 3: Structures, such as the waxy coating of a cactus or the presence of spines instead of leaves, help these plants survive in hot, dry conditions.

13 Traits Key Concept 1: Some characteristics are inherited, while others are learned in response to the environment Inherited characteristics are passed from parent to offspring through reproduction. Offspring are the children, or offshoots, from a parent. The number of limbs, the color of fur, and the shape of a beak are examples of traits (internal or external characteristic or feature) that are inherited from the parent organism. These characteristics are not received after birth, but are part of the genetic code passed on to offspring during reproduction and determine internal and external structures. Behaviors, on the other hand, are movements or actions that are taught or learned after birth. Riding a bicycle, knowing where to find prey, and rolling over for a treat are examples of behaviors that are not inherited, but must be learned.

14 Traits Key Concept 2: Inherited characteristics include mainly physical characteristics, such as fins on a fish, stripes on a tiger, or the yellow color of a daffodil. Every structure, size, whether it be big or small, color, shape, and the number of parts in every plant or animal is inherited through traits passed down from parent to offspring. Every physical characteristic a living thing is born with represents an inherited trait. Although general characteristics among the same species are similar and passed on to each generation, such as all spiders have eight legs, the individual variations that make each plant or animal unique result from the random combination of genes passed down from the parents.

15 Traits Key Concept 3: Learned behaviors include using tools, such as a chimp s use of sticks to retrieve termites from mounds or a sea otter s use of pebbles to open shellfish.

16 Life Cycles Key Concept 1: Organisms undergo observable changes during their life cycles, including birth, growth and development, reproduction, and death. Young plants (seedlings), such as tomato plants usually resemble their parents, though smaller in size. Their leaves, color, and shape will copy their parents.

17 Life Cycles Amphibians, such as frogs, have completely different life cycles. Frogs change their appearances from childhood to adulthood. This is called complete metamorphosis. Frogs lay floating clumps of soft, jellylike eggs in water. The eggs hatch into a water breathing, fishlike tadpole with gills and no limbs. Slowly, legs develop, and the tadpole tail shortens. Adult frogs become air breathing, land animals, with fully-grown legs and lungs.

18 Life Cycles Insects also experience a complete change in their appearances during their life cycle. For example, butterflies and ladybugs have four stages of life: (1) Egg, or unborn stage (2) Larva, the young stage when most feeding is done and the insects look like worms (3) Pupa, the no-feeding stage when the insect is camouflaged insides a sac and changes from a worm shape to a full grown insect (4) Adult, the stage when the insect leaves the pupa, usually has wings, and is ready for reproduction.