Big Idea 4

Big Idea 4: 1. Altruistic behavior

This picture shows a normally beautiful organism (though it is rather frumpy in the photo) giving a $25 gift card to its always-ugly younger sibling. It demonstrates the idea of altruistic behavior. Altruistic behavior is behavior that may reduce an organism's own individual fitness in order to increase the fitness of another individual in the same population. In the picture, the taller organism reduces its fitness because it does not have as much money to spend, but the shorter organism gains more money to spend.

Big Idea 4: 3. Biomes #1 (Savanna)

A biome is a major type of ecological association that occupies a broad geographic region of water or land. The focus of this picture is the environment, even though there is a giraffe in it. The environment is characteristic of what might be found in a savanna biome in Africa.

Big Idea 4: 3. Biomes #2 (Freshwater)

A biome is a major type of ecological association that occupies a broad geographic region of water or land. The photo shows what a freshwater biome could look like, with water, aquatic plants and rocks and sand on the floor.

Big Idea 4: 3. Biomes #3 (Desert)

A biome is a major type of ecological association that occupies a broad geographic region of water or land. This sample of a desert biome is sandy and rocky with some wood. Contrary to popular conception, greenery and plant life are present in the desert.

Big Idea 4: 3. Biomes #4 (Tropical rainforest)

A biome is a major type of ecological association that occupies a broad geographic region of water or land. The tropical rainforest is one of the most diverse types of biomes. As seen in the photograph, it has fertile soil and lots of trees. Although there is no water in the picture, the darkness of the leaves and of the tree on the left indicate a moist environment.

Big Idea 4: 6. Competition

Competition is a contest between organisms for something needed or desired, such as territory or food and resources. This plant in my mom's garden is competing for territory with the other plants (and it is winning too; it is even invading the sidewalk on the far side.)

Big Idea 4: 8. Endosperm

Endosperm is tissue in a plant seed that is rich in starch and other food reserves. There is endosperm present in popcorn kernels such as these depicted in the photo; in fact, it makes up about 80% of the weight of the kernel.

Big Idea 4: 9. Introduced species

An introduced species is a species that is nonnative to the area that it inhabits as a result of being moved by humans, accidentally or intentionally. This ostrich is an example of an introduced species because it was introduced to California from its native Africa.

Big Idea 4: 11. K-strategist

K-strategists are organisms whose reproduction is sensitive to population density. Their reproduction involves less offspring, but greater attention paid to the welfare of the offspring. K-strategy is favorable in a stable environment because the offspring have a high chance of survival. Giraffes are k-strategists; they take full care of their young until the young are able to fend for themselves.

Big Idea 4: 19. R-strategist

R-strategists are organisms whose reproduction is independent of population density. Their reproduction involves a very high number of offspring, but with very little attention paid to each offspring. R-strategy is favorable in an unstable environment because the environment is likely to change frequently, so the parent needs to have as many young as possible in order to ensure greater reproductive success. Weeds are r-strategists because they spread wide and very fast; they spring back up less than a week after I pull them out of the ground.