Solved: Plastids that are surrounded by more than two membranes are evidence of a

The oldest fossil eukaryote that can be resolved taxonomically is of a. a red alga that lived 1.2 billion years ago. b. a red alga that lived 635 million years ago. c. a fungus that lived 2 billion years ago. d. a fungus that lived 550 million years ago. e. an Ediacaran that lived 550 million years ago.

The evolution of complex multicellularity in eukaryotes a. occurred only once, in the common ancestor of all eukaryotes. b. occurred only once, in the common ancestor of all multicellular eukaryotes. c. occurred only once, in the animal lineage. d. is not documented by the fossil record. e. occurred independently in several different eukaryotic lineages

Plastids that are surrounded by more than two membranes are evidence of a. evolution from mitochondria. b. fusion of plastids. c. origin of the plastids from archaea. d. secondary endosymbiosis. e. budding of the plastids from the nuclear envelope.

Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because a. the products of photosynthesis could not be metabolized without mitochondrial enzymes. b. all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids. c. mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA. d. without mitochondrial CO2 production, photosynthesis could not occur. e. mitochondrial proteins are synthesized on cytosolic ribosomes, whereas plastids utilize their own ribosomes.

Which group is incorrectly paired with its description? a. rhizariansmorphologically diverse group that includes amoebas with threadlike pseudopodia b. diatomsimportant producers in aquatic communities c. red algaeacquired plastids by secondary endosymbiosis d. apicomplexansparasites with intricate life cycles e. diplomonadsprotists with modified mitochondria

Based on the phylogenetic tree in Figure 25.9, which of the following statements is correct? a. The most recent common ancestor of Excavata is older than that of the SAR clade. b. The most recent common ancestor of the SAR clade is older than that of Unikonta. c. The most recent common ancestor of red algae and land plants is older than that of nucleariids and fungi. d. The most basal (first to diverge) eukaryotic supergroup cannot be determined. e. Excavata is the most basal eukaryotic supergroup.

The bacterium Wolbachia is a symbiont that lives in mosquito cells and spreads rapidly through mosquito populations. Wolbachia can make mosquitoes resistant to infection by Plasmodium; researchers are seeking a strain that confers resistance and does not harm mosquitoes. Compare evolutionary changes that could occur if malaria control is attempted using such a Wolbachia strain versus using insecticides to kill mosquitoes. (Review Figure 25.26 and Concept 21.3.)

Applying the If then logic of science (see Chapter 1), what are a few of the predictions that arise from the hypothesis that plants evolved from green algae? Put another way, how could you test this hypothesis?

Medical researchers seek to develop drugs that can kill or restrict the growth of human pathogens yet have few harmful effects on patients. These drugs often work by disrupting the metabolism of the pathogen or by targeting its structural features. Draw and label a phylogenetic tree that includes an ancestral prokaryote and the following groups of organisms: Excavata, the SAR clade, Archaeplastida, Unikonta, and, within Unikonta, amoebozoans, animals, choanoflagellates, fungi, and nucleariids. Based on this tree, hypothesize whether it would be most difficult to develop drugs to combat human pathogens that are prokaryotes, protists, animals, or fungi. (You do not need to consider the evolution of drug resistance by the pathogen

Organisms interact with each other and the physical environment. In a short essay (100150 words), explain how the response of diatom populations to a drop in nutrient availability can affect both other organisms and aspects of the physical environment (such as carbon dioxide concentrations).