General Biology 2: Viruses, Prokaryotes, Protists, and Plant Evolution

Comprehensive practice fill-in-the-blank flashcards covering viral biology, prokaryotic taxonomy and genetics, protist diversity and life cycles, and the evolutionary transition to land plants.

When a virus is outside of a host cell, it is metabolically inert and referred to as a __________.

virion

Retroviruses such as HIV contain an infectious viral genome consisting of __________ identical single-stranded RNA molecules.

two

The specialized retroviral enzyme that synthesizes double-stranded DNA using viral RNA as a template is __________.

reverse transcriptase

In honey bees (Apies mellifera), Deformed Wing Virus is transmitted by the parasitic mite __________.

Varroa jacobsoni

The specificity of a virus that restricts it to infecting only certain tissues inside a host is known as __________.

tissue tropism

In bacteriophages, the reproductive cycle in which the viral DNA integrates into the host chromosome as a dormant prophage without immediately killing the cell is called the __________ cycle.

lysogenic

During HIV infection, the viral glycoprotein __________ attaches to the human CD4 protein on helper T cells and macrophages.

gp120

Human individuals who harbor a specific mutation in the cell surface co-receptor protein __________ are resistant to HIV infection.

CCR5

The primary mechanism triggering the death of HIV-infected $CD4^+$ T cells due to incomplete viral DNA products is called __________.

pyroptosis

A viral genome that has integrated stably into the DNA of a eukaryotic host cell is known as a __________.

provirus

Highly active antiretroviral therapy (HAART) has reduced the U.S. AIDS death rate by __________ since its introduction in the mid-1990s.

three-fourths

The coronavirus SARS-CoV-2 enters human host cells by binding its Spike protein to the human cell-surface receptor __________.

ACE2

The SARS-CoV-2 single-stranded RNA genome spans approximately __________ nucleotides and encodes 20 proteins.

30,000

The 12-nucleotide insertion mutation in the Spike protein of SARS-CoV-2 that contributed to its aggressive pandemic transmission has the sequence __________.

CCUCGGCGGGCA

Because Bacteria and Archaea share a common ancestor but do not include all descendants of that common ancestor, prokaryotes form a __________ group.

paraphyletic

Unlike Bacteria and Eukarya which possess ester links in their plasma membranes, Archaea possess membrane lipids connected by __________ links.

ether

The cell walls of Archaea lack peptidoglycan and instead contain a similar carbohydrate polymer known as __________.

pseudomurein

Bacteria characterized by a thin peptidoglycan layer surrounded by a second outer membrane containing lipopolysaccharides are classified as __________ bacteria.

Gram-negative

During bacterial conjugation in Escherichia coli, an $F^+$ donor connects to an $F^-$ recipient cell using an elongated protein structure termed the __________.

F pilus

A bacterial cell in which the fertility (F) plasmid has integrated into the main bacterial chromosome is termed an __________ cell.

Hfr

The mode of horizontal gene transfer in which an excised prophage takes adjoining host bacterial genes with it upon exiting the host chromosome is called __________.

specialized transduction

A life cycle in which all multicellular individuals and tissues are diploid, and gametes are the only haploid stage, is called a __________ life cycle.

diplontic

In a haplontic life cycle, the only diploid structure in the entire cycle is the __________.

zygote

The alternation of multicellular haploid (gametophyte) and multicellular diploid (sporophyte) generations is characteristic of a __________ life cycle.

haplodiplontic

According to the endosymbiotic theory, ancestral mitochondria originated from engulfed __________ bacteria.

Rickettsia

In Apicomplexans, the non-photosynthetic relictual chloroplast essential for lipid biosynthesis, iron metabolism, and host cell penetration is called the __________.

apicoplast

During the life cycle of the malaria parasite Plasmodium, haploid individuals produced by meiosis that later develop into gametes inside mosquitoes are called __________.

gametocytes

Although most brown algae exhibit a haplodiplontic alternation of generations, the brown alga genus __________ is an exception that possesses a diplontic life cycle.

Fucus

The anaerobic diplomonad shown here, which possesses two identical nuclei and reduced mitochondria called mitosomes, is __________.

Giardia lamblia

Kinetoplastids possess a unique, single mitochondrion containing interlocked circles of mitochondrial DNA called a __________.

kinetoplast

The insect vector pictured below that transmits Trypanosoma cruzi, the causative agent of Chagas disease, is __________.

Triatoma rubida

The opportunistic 'brain-eating amoeba' that exhibits cyst, amoeboid, and flagellated morphological stages is __________.

Naegleria fowleri

The protist group closest to animals, whose members possess a funnel-shaped contractile collar structurally homologous to sponge choanocytes, is the __________.

choanoflagellates

The photosynthetic supergroup Archaeplastida acquired its chloroplasts via __________ endosymbiosis.

primary

Red algae (Rhodophyta) harvest light in deep water using the accessory pigment-protein complex __________, which reflects red light and absorbs blue light.

phycoerythrin

Harmful toxic red tides are produced by haplontic, unicellular protists belonging to the clade __________.

dinoflagellates

In coral bleaching, corals expel endosymbiotic photosynthetic dinoflagellates belonging to the genus __________.

Symbiodinium

Green algae form a paraphyletic group because they consist of chlorophytes and charophytes but exclude the __________.

land plants

The unicellular chlorophyte model organism that possesses two anterior flagella and displays a haplontic life cycle is __________.

Chlamydomonas reinhardtii

The multicellular marine chlorophyte known as sea lettuce, which displays an isomorphic haplodiplontic life cycle, is __________.

Ulva

In the haplontic charophyte Chara, the single diploid cell that subsequently undergoes meiosis to produce haploid progeny is the __________.

cystozygote

In nonvascular bryophytes, the multicellular female gametangium that produces eggs is called the __________.

archegonium

In the liverwort life cycle shown below, umbrella-shaped structures that produce male gametes inside antheridia are called __________ heads.

antheridial

Bryophytes lack true roots and are instead anchored to substrates by non-absorptive, hair-like filaments called __________.

rhizoids

Vascular plant leaves containing only a single unbranched vascular strand, found exclusively in Lycophytes, are called __________.

lycophylls

True leaves with branched vascular networks that evolved from webbed branching stem systems in euphyllophytes are termed __________.

euphylls

The seedless vascular plant shown below, which lacks true roots and leaves but has dichotomously branching photosynthetic stems and enations, is __________.

Psilotum nudum

In ferns and their allies (Monilophytes), the tiny, heart-shaped multicellular gametophyte structure is called the __________.

prothallus