biology 20 & 23

What is the structure of a virus composed of?

An outer capsid made of protein subunits and a nucleic acid core made of either DNA or RNA.

What occurs during the lytic cycle of bacteriophages?

The release of new viruses lyses (ruptures) the host cell.

What characterizes the lysogenic cycle of bacteriophages?

Viral DNA inserts into the host cell chromosome, does not actively replicate, and may later trigger re-entry into the lytic cycle.

What is the life cycle of a retrovirus?

Viral RNA enters the cell, is used to make DNA, which inserts into the host chromosome; new viral RNA and capsids are produced by the host cell and released by budding.

Describe conjugation in gene transfer among bacteria.

Two bacteria are temporarily linked, allowing a donor cell to pass DNA to a recipient cell in the form of a plasmid.

What is transformation in bacterial gene transfer?

It occurs when a cell picks up free pieces of DNA from live or dead prokaryotes.

What is transduction in bacteria?

Bacteriophages carry portions of DNA from one bacterial cell to another.

What is the primary difference between autotrophs and heterotrophs?

Autotrophs make their own food, while heterotrophs rely on other organisms for food.

List and describe the three main shapes of bacteria.

Spirilli: spiral-shaped; Bacilli: rod-shaped; Cocci: round or spherical.

What is alternation of generations in plants?

Two multicellular individuals alternate, where a diploid sporophyte produces haploid spores that develop into haploid gametophytes, which then produce gametes to form a diploid zygote.

What are sepals in a complete flower?

They protect the bud before it opens and are collectively called the calyx.

What are petals in a complete flower?

Colored leaflets that constitute the corolla.

What is the function of stamens in a flower?

They are the male parts consisting of filaments and anthers where pollen is produced.

What are carpel parts in a flower?

The female parts including the stigma, stalk, and ovary.

What defines a complete flower?

A complete flower has all four parts: sepals, petals, stamens, and carpels.

List the characteristics of all plants.

Multicellular, eukaryotes, usually specialized tissues, photosynthesizers adapted to land, with an alternation-of-generations life cycle, and sessile.

What is the definition of fruit in the context of plants?

A covering for a seed derived from an ovary.

What is an archegonium?

The female gametangia that produces eggs.

What is an antheridium?

The male gametangia that produces sperm.

What plants are bryophytes

Mosses

What plants are seedless vascular plants

Ferns

What plants are gmnosperms

Cone bearing plants

What plants are angiosperms

Flowering plants

List the characteristics of all plants

Multicellular, eukaryotes, usually specialized tissues, photosynthesizers that became adapted to living on land, alternation-of-generation life cycle, sessile

Define Fruit

A covering got a seed derived from an ovary