Biology

primate, hominid

Hominids are a subgroup of primates that can walk upright on two feet. Primates are an order of mammals with flexible hands and feet, forward-looking eyes, and large brains relative to body size. Primates also have arms that can rotate in a

What basic idea does cladistics use to classify groups of organisms?

common ancestry, or descent from a common ancestor

bipedal

the ability to walk upright on two legs

Analyze How many clades are represented in this cladogram?

3; one with A, B, C, and D; one with B, C, and D; and one with C and D

binomial nomenclature, genus, species

Binomial nomenclature is a system used to give each species a two-part scientific name, which includes a genus name and a species descriptor.

Current technology allows scientists to examine organ- isms at the molecular level. How has this technology exposed limitations in Linnaean taxonomy?

By studying species at the molecular level, scientists can compare the DNA of different species. Similarities in DNA are likely due to relatedness, while physical and structural similarities between species may be the result of convergent evolution and therefore not indicative of actual relatedness. Molecu- lar evidence has led scientists to reclassify into different groups some species that were originally thought to be closely related based on physical similarities alone.

cyanobacteria, endosymbiosis

Cyanobacteria are prokaryotes. Endosymbiosis is a theory that suggests that prokary- otes may have absorbed other prokaryotes, such as precursors of mitochondria and chloroplasts, and evolved into eukaryotes.

What are two ways that cyanobacteria have changed the physical or chemical composition of Earth?

Cyanobacteria, being photosynthetic, have produced oxygen for Earth's atmosphere and oceans, and have also deposited minerals.

One evolutionary advantage of sexual reproduction is that it creates more genetic variation in a population than asexual reproduction. Why might this be an advantage?

Genetic variation is advantageous because it increases the chances that some individuals will have genes that are beneficial for survival in a certain environment. Without genetic variation, the entire population is vulnerable to environmental change.

What genus do humans belong to

Homo

Name the seven levels of organization in Linnaean taxonomy, from the most general to the most specific

Kingdom, Phylum, Class, Order, Family, Genus, Species

Bacteria, Archaea, Eukarya

Life forms are currently divided into three domains: Bacteria, Archaea, and Eukarya.

Where are the nodes in this cladogram, and what do they represent?

Nodes are where the side branches intersect with the main branch. They represent the common ancestor of the species in each clade.

Why is it important for biologists to include scientific names when reporting their research to other biologists around the world?

Scientific names are recognized by scientists around the world, no matter what languages they speak. This allows for clear communication. Also, there is only one scientific name given to each species, whereas one species may have many common names in just one language, and hundreds across multiple languages.

The Miller-Urey experiment and the meteorite hypothesis both suggest how the molecules that can support life might have appeared on early Earth. What is the main difference between these two hypotheses? Explain

The Miller-Urey experiment proposes that life began from the formation of organic compounds from available inorganic compounds. The meteorite hypothesis proposes that a meteor containing organic molecules, namely amino acids, hit Earth.

What evidence exists to support the endosymbiotic origins of eukaryotic cells?

The endosymbiotic theory is based on mitochondria and chloroplasts of eukaryotes. Both structures have characteristics (such as their own DNA and the ability to self-replicate) of independent prokaryotes.

What distinguishes the three domains in the tree of life from one another?

The structure of cells distinguishes the three domains. Bacteria and Archaea both have prokaryotic cells, but their cell walls are chemically different. Eukarya have eukaryotic cells.

What represents the derived characters that were used to construct this cladogram?

hash marks 1, 2, 3, and 4