Question

chapter 1 study guide
7th grade life science

1. list the taxonomic groups from largest to smallest. approximately how many species in each?

taxonomic group	number of species
kingdom animal	2 million
phylum chordate	50,000
class mammalia	5,000
order carnivora	270
family ursidae	8
genus ursus	4
species ursus	1

1. what is a cladogram? how is a family tree show the relationship among family member
2. what is a dichotomous key?
3. what are the six characteristics of living things?
4. what is a reaction to stimulus? what is an example of a reaction to an external stimulus? to an internal stimulus?

Explanation:

1. Taxonomic groups from largest to smallest are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. The numbers of species provided are approximate estimates for the given groups.
2. A cladogram is a diagram that shows the evolutionary relationships among groups of organisms. A family - tree shows the relationship among family members, but it is not the same as a cladogram which focuses on evolutionary relationships.
3. A dichotomous key is a tool used to identify organisms. It consists of a series of paired statements or questions that lead the user to the identification of the organism.
4. The six characteristics of living things are: made of cells, reproduce, have a universal genetic code, grow and develop, obtain and use materials and energy, respond to their environment, and maintain a stable internal environment (homeostasis).
5. A reaction to a stimulus is a change in behavior or physiology in response to a change in the environment. An example of a reaction to an external stimulus could be a plant growing towards light (phototropism). An example of a reaction to an internal stimulus could be a person feeling hungry (response to low blood - sugar levels, an internal condition).

Answer:

1. Taxonomic groups: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. Approximate species numbers as in the table.
2. A cladogram shows evolutionary relationships among groups of organisms. A family - tree shows family relationships.
3. A dichotomous key is a tool for organism identification with paired statements/questions.
4. Made of cells, reproduce, have genetic code, grow/develop, obtain/use materials and energy, respond to environment, maintain homeostasis.
5. Reaction to stimulus is a change in response to environment change. External: plant growing towards light. Internal: feeling hungry.