The endosymbiotic theory is a scientific explanation concerning the complexity of the cell. It is the theory that the mitochondria and chloroplasts contained within modern animal and plant cells were once free living bacteria that were engulfed by another bacterial cell leading to the ____________ cell.

Which two scientists conducted an experiment that simulated conditions present on the primitive Earth and tested for the occurrence of chemical evolution?

Scientists have duplicated the chemical conditions of the early oceans and atmosphere inside an apparatus in a controlled laboratory experiment. The chemicals were subjected to an energy source in the form of electric sparks. The resulting compounds of the classical experiment were

A dichotomous key of different mollusks is shown. Which mollusk moves by jet propulsion and does not have an external shell?

Why is it important to assign each organism a scientific name?

Which characteristic do all organisms in Kingdoms Animalia, Protista, and Fungi have in common?

The table shows the classification of four mammals found in Texas. Based on this table, which explanation best describes why elk and fallow deer are classified in the same genus?

A phylogenetic tree based on genetic similarities is shown. Which numbered location on the phylogenetic tree identifies characteristics shared by Species B, C, and D?

A cladogram of five species is shown. Based on the cladogram, the ancestral species most likely had —

A researcher determines an organism to be eukaryotic, unicellular, and autotrophic. In which taxonomic group should this organism be classified?

Students examine images of a certain species of bat commonly found in Texas. Using the bat dichotomous key, they conclude that the bat species is a Mexican free-tailed bat due to its large, round ears. Based on the dichotomous key, in addition to the shape of the bat’s ears, which other set of features should the students look for to confirm the identity of the bat?

The taxonomic classifications of four species of amphibians are shown. Based on the information provided, which two species are most closely related?

Researchers analyzed a mitochondrial gene of different bat species to determine relatedness. A cladogram of their results is shown. Based on the cladogram, which set of bat species is the least related?

Students use a microscope to look for structures present in four different cells. The students placed an X for each structure that was viewed for each cell on the table shown. Which cell that was viewed is most likely a prokaryote?

Many tree frog populations are threatened due to habitat loss. In an effort to promote conservation, tree frogs may be bred in captivity. A zoo acquired male and female tree frogs from two different populations. In the zoo, the tree frogs were able to successfully mate within their own population, but breeding attempts between the two populations were unsuccessful. Based on this information, which statement correctly describes the relationship between the two populations of tree frogs?

A student used a microscope to study four members of the phylum Ciliophora. Members of this phylum move when propelled by hundreds of tiny cilia. Although these organisms belong to the same phylum, they are classified as different —

Students are given data from an investigation that identified some of the chemical elements present in four different samples. Which sample was most likely DNA?

Researchers studying populations of lizards from the genus Gallotia on the Canary Islands compared the protein cytochrome b in different populations. The table shows the number of differences in the cytochrome b protein between different populations. Which conclusion about the relatedness of the lizards do these data support?

Which diagram demonstrates how crossing-over contributes to genetic variety during meiosis?

Poison ivy is also known as Rhus toxicodendron. Its species identifier is ______

Which of these gasses was not a part of the early Earth atmosphere?

Photosynthesis and cellular respiration both involve the use and release of gasses. Which statement correctly identifies the role of gasses in the two processes?

A model of a biological process is shown. What is the purpose of this process?