Exam 25: The Origin and Diversification of Eukaryotes

Please use the following information to answer the question(s) below. Giardia intestinalis is an intestinal parasite of humans and other mammals that causes intestinal ailments in most people. It can infect people when they drink water contaminated with feces containing Giardia cysts. Upon ingestion, each cyst releases two motile cells, called trophozoites. These attach to the small intestine's lining via a ventral adhesive disk. The trophozoites anaerobically metabolize glucose from the host's intestinal contents to produce ATP. Reproduction is completely asexual, occurring by longitudinal binary fission of trophozoites, with each daughter cell receiving two haploid nuclei (n = 5). A trophozoite will often encyst as it passes into the large intestine by secreting around itself a case that is resistant to cold, heat, and dehydration. -During passage through the large intestine, a trophozoite will often secrete a case around itself, forming a cyst. Cysts contain four haploid nuclei. When cysts "hatch" within a new host, two trophozoites are released. Thus, which of the following must happen within the cyst prior to hatching? 1) meiosis 2) nuclear division 3) S phase 4) binary fission

You discover a new species of aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (for example, 250 m deep). It can also crawl about and engulf small particles. Which two characteristics does your protist have to have in order to successfully complete these tasks? 1) hydrogenosome 2) apicoplast 3) pseudopods 4) chloroplast from red alga 5) chloroplast from green alga

Please use the following information to answer the question(s) below. You are given four test tubes, each containing an unknown protist. Your task is to read the following description and match these four protists to the correct test tube. When red and blue light are shone on the tubes, oxygen bubbles accumulate on the inside of test tubes 1 and 2. Chemical analysis of test tube 1 indicates the presence of a chemical that is toxic to fish and humans. Chemical analysis of test tube 2 indicates the presence of substantial amounts of silica. Microscopic analysis of organisms in test tube 3 reveals the presence of an apicoplast in each. Microscopic analysis of the contents in test tube 4 reveals thousands of cilia on the surface of the organism. -Test tube 3 contains

Please use the following information to answer the question(s) below. Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. -If true, which of the following would be most important in determining whether P. chromatophora's cyanelle is still an endosymbiont or is an organelle, as the term cyanelle implies?

An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?

Which of the following is the most likely sequence of events, from earliest to most recent, in the evolution of sponges (organisms with many cells that have different functions)? 1) single-celled eukaryote 2) single-celled prokaryote 3) multicellular eukaryote 4) colonial eukaryote

Please use the following information to answer the question(s) below. Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gathers at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1) if kept in darkness, the algae will die; and (2) if prey items (mostly bacteria) are absent from its habitat, P. bursaria will digest its zoochlorellae. -A P. bursaria cell that has lost its zoochlorellae is said to be aposymbiotic. It might be able to replenish its contingent of zoochlorellae by ingesting them without subsequently digesting them. Which of the following situations would be most favorable to the reestablishment of resident zoochlorellae, assuming that compatible Chlorella are present in P. bursaria's habitat?

Which of the following organism pairs is/are an example of secondary endosymbiosis? I. red algae-heterotrophic eukaryote II. green algae-heterotrophic eukaryote III. E. coli bacteria-photosynthetic cyanobacterium IV. Chlamydomonas and Gonium

A biologist discovers an alga that is marine, multicellular, and can absorb both green and blue light. This alga probably belongs to which group?

Based on the phylogenetic tree in the figure given below, which of the following statements is correct?

Which of the following is correctly described as a primary producer?

Please use the following information to answer the question(s) below. Healthy individuals of Paramecium bursaria contain photosynthetic algal endosymbionts of the genus Chlorella. When within their hosts, the algae are referred to as zoochlorellae. In aquaria with light coming from only one side, P. bursaria gathers at the well-lit side, whereas other species of Paramecium gather at the opposite side. The zoochlorellae provide their hosts with glucose and oxygen, and P. bursaria provides its zoochlorellae with protection and motility. P. bursaria can lose its zoochlorellae in two ways: (1) if kept in darkness, the algae will die; and (2) if prey items (mostly bacteria) are absent from its habitat, P. bursaria will digest its zoochlorellae. -Which term best describes the symbiotic relationship of well-fed P. bursaria with their zoochlorellae?

Living diatoms contain brownish plastids. If global warming causes blooms of diatoms in the surface waters of Earth's oceans, how might this be harmful to the animals that build coral reefs?

Please use the following information to answer the question(s) below. Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. -The closest living relative of P. chromatophora is the heterotroph P. ovalis. P. ovalis uses threadlike pseudopods to capture its prey, which it digests internally. Which of the following, if observed, would be the best reason for relabeling P. chromatophora as a mixotroph?

Which of the following was derived from an ancestral cyanobacterium?

Please use the following information to answer the question(s) below. Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "cyanelles." The cyanelles are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. -If true, which of the following is the best evidence that the cyanelles are providing nutrition (in other words, calories) to the surrounding cercozoan?

The evolution of multicellularity in animals has primarily occurred by

Why can eukaryotes be considered "combination" organisms?

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth? 1) origin of mitochondria 2) origin of multicellular eukaryotes 3) origin of chloroplasts 4) origin of cyanobacteria 5) origin of fungal-plant symbioses

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?