Comprehensive Quizlet: Bacteria, Protists, and Plant Diversity

What is phototaxis?

Movement toward or away from light.

What is an endospore?

A dormant, resistant structure that allows bacteria to survive harsh conditions.

What is binary fission?

Asexual reproduction in which one cell divides into two identical cells.

What is a phototroph?

An organism that uses light as an energy source.

What is a chemotroph?

An organism that uses chemical compounds as an energy source.

What is an autotroph?

An organism that uses inorganic carbon (CO₂) as a carbon source.

What is a heterotroph?

An organism that uses organic compounds as a carbon source.

What is an obligate aerobe?

An organism that requires oxygen for cellular respiration.

What is a facultative anaerobe?

An organism that can survive with or without oxygen.

What is an obligate anaerobe?

An organism that is poisoned by oxygen.

What is transformation in bacteria?

The uptake of naked DNA from the environment.

What is transduction?

Gene transfer via bacteriophages (viruses).

What is conjugation?

Direct transfer of DNA between cells via a pilus.

What is a halophile?

An organism that thrives in high-salt environments.

What is a thermophile?

An organism that thrives in extremely hot environments.

What is a methanogen?

An archaeon that produces methane as a waste product.

What is symbiosis?

A close ecological relationship between two species.

What is mutualism?

A relationship where both species benefit.

What is commensalism?

A relationship where one species benefits and the other is unaffected.

What is parasitism?

A relationship where one species benefits and the host is harmed.

What is an exotoxin?

A toxin secreted by living bacteria.

What is an endotoxin?

A toxin released when Gram-negative bacteria die and their cell walls break down.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What are basic characteristics of prokaryotes?

No nucleus, no membrane-bound organelles, unicellular, small size, circular chromosome.

What are the three main shapes of prokaryotic cells?

Coccus (spherical), Bacillus (rod-shaped), Spirillum (spiral-shaped).

What substance do all bacterial cell walls contain?

Peptidoglycan.

How does the cell wall of a Gram-positive bacterium differ from that of a Gram-negative bacterium?

Gram-positive has a thick peptidoglycan layer and retains crystal violet stain; Gram-negative has a thin peptidoglycan layer and does not retain stain.

What functions are served by the cell wall of bacteria?

Maintains cell shape, provides physical protection, prevents cell lysis in hypotonic environments.

Why are Gram-negative pathogens generally more threatening than Gram-positive ones?

They have endotoxins in their outer membrane that are released upon cell death.

How does penicillin inhibit bacterial growth?

It interferes with the synthesis of peptidoglycan, weakening the cell wall.

Does penicillin affect Gram-positive or Gram-negative bacteria?

Penicillin affects Gram-positive bacteria.

What is a capsule and what is its function?

A sticky layer surrounding the cell wall that helps bacteria adhere to surfaces and evade the host immune system.

What are fimbriae and pili?

Thin attachments to bacterial surfaces used for adherence and DNA transfer during conjugation.

What is a plasmid?

A small, circular, extrachromosomal DNA molecule that carries genes for survival.

How do antibiotics like gentamicin, neomycin, and doxycycline inhibit bacterial growth?

They inhibit bacterial growth through protein synthesis by targeting bacterial ribosomes.

What is horizontal gene transfer?

The transfer of genes between organisms without reproduction.

What are the three mechanisms prokaryotes use to transfer genes?

Transformation, Transduction, Conjugation.

What are photoautotrophs?

Organisms that use light energy and inorganic carbon.

What are chemoautotrophs?

Organisms that use chemical energy and inorganic carbon.

What are photoheterotrophs?

Organisms that use light energy and organic carbon.

What are chemoheterotrophs?

Organisms that use chemical energy and organic carbon.

What are the oxygen requirements for obligate aerobes?

They require oxygen and cannot survive without it.

What are the oxygen requirements for obligate anaerobes?

Oxygen is toxic to them, and they cannot survive with it.

What are the oxygen requirements for facultative anaerobes?

They prefer oxygen but can survive without it.

What are some characteristics of archaea?

More like eukaryotes than bacteria, nonpathogenic, lack peptidoglycan, many are extremophiles.

What is the relationship between a symbiont and its host in mutualism?

Both symbiont and host benefit.

What is the difference between an exotoxin and an endotoxin?

Exotoxins are secreted by living bacteria; endotoxins are released when Gram-negative bacteria die.

What are the characteristics of diatoms?

Unicellular; silica cell walls; major phytoplankton.

What are the characteristics of brown algae?

Multicellular marine algae; largest and most complex algae; contain fucoxanthin.

What are the characteristics of dinoflagellates?

Two flagella; cellulose plates; cause red tides.

What are the characteristics of apicomplexans?

Parasites with an apex; complex life cycles (e.g., Plasmodium).

What are the characteristics of ciliates?

Use cilia; have oral groove and contractile vacuole.

What are the characteristics of radiolarians?

Silica skeletons; radiating pseudopodia.

What are the characteristics of foraminiferans?

Calcium carbonate shells; porous tests with pseudopodia.

What is a red tide?

A toxic algal bloom caused by dinoflagellates; produces toxins that kill fish and can harm humans.

What disease does Plasmodium cause?

Malaria.

What is the vector for malaria?

The Anopheles mosquito.

What disease does Toxoplasma gondii cause?

Toxoplasmosis.

What are some observations of organisms infected by T. gondii?

Usually mild but dangerous for pregnant or immunocompromised individuals; can alter host behavior.

What supergroup do red algae, green algae, and plants belong to?

Archaeplastida.

What are the characteristics of red algae?

Mostly multicellular, pigments give red coloration, source of agar and carrageenan.

What are the characteristics of green algae?

Diverse (unicellular, colonial, multicellular), contains chlorophytes and charophytes.

Which group of green algae are believed to share a common ancestor with plants?

Charophytes.

What is a sporophyte?

Diploid, spore-producing generation.

What is a gametophyte?

Haploid, gamete-producing generation.

What is homospory?

One type of spore produced.

What is heterospory?

Two types of spores (microspores and megaspores).

What is a sporangium?

Structure where spores are produced.

What is a rhizoid?

Root-like structure for anchorage.

What is a sorus?

Cluster of sporangia on fern leaves.

What is a sporophyll?

Leaf that bears sporangia.

What is a strobilus?

Cone-like structure composed of sporophylls.

What challenges did plants have to overcome to live in a terrestrial environment?

Temperature variation, water loss, gravity, support and anchorage, reproduction without water.

What traits are found in plants but not charophytes?

Alternation of generations, walled spores in sporangia, apical meristems, waxy cuticle, stomata.

What are the important characteristics of non-vascular plants?

Lack xylem and phloem; gametophyte dominant; require water for fertilization; have rhizoids instead of roots.

What is the difference between archegonia and antheridia?

Archegonia produce eggs; antheridia produce sperm.

What are the important characteristics of seedless vascular plants?

Have xylem and phloem; sporophytes dominate; require water for fertilization; reproduce by spores.

What is the difference between xylem and phloem?

Xylem transports water and minerals; phloem transports sugars and organic nutrients.

What are the important characteristics of gymnosperms?

Seed-bearing vascular plants; dominant sporophyte; heterosporous; produce pollen grains; seeds develop on cones.

What are the important characteristics of angiosperms?

Flowers; double fertilization; fruits; seeds enclosed in ovaries; dominant sporophyte.

What are the three parts of a seed?

Embryo, seed coat (for protection), food supply (nourishes the embryo).

What are the names of female and male pinecones?

Female pinecones are known as 'ovulate cones'; male pinecones are known as 'pollen cones'.

What are the three 'Fs' that characterize angiosperms?

Flowers, Fruits, double Fertilization.

What occurs during double fertilization?

One sperm fertilizes the egg, resulting in a zygote (2n); another sperm fertilizes the polar nuclei, resulting in endosperm (3n).

What is the name of the one angiosperm phylum?

Phylum Anthophyta.