The Spread of Viral Disease and Introduction to Body & Plant Systems

A comprehensive set of question-and-answer flashcards covering viral spread, host defenses, biological organization, animal body functions, and major plant structures and responses.

What is a virus?

A non-living, infectious particle (virion) that requires a host cell to replicate and can cause disease.

What does the word 'pathogenic' mean when referring to a virus?

Disease-causing.

Why do viruses need host cells to reproduce?

Viruses contain genetic instructions (DNA or RNA) but lack the ribosomes and other machinery required for protein synthesis and replication.

Which viral replication cycle kills the host cell quickly and releases new virions?

The lytic cycle.

Which viral replication cycle can remain dormant by integrating its genome into the host’s DNA?

The lysogenic cycle.

Name two environmental stressors that can trigger a lysogenic virus to enter the lytic cycle.

UV radiation, chemical exposure, or starvation (any two).

Give a viral example that commonly follows the lytic cycle.

Influenza virus.

Give a viral example that can remain lysogenic before becoming lytic.

HIV.

Define a virus reservoir.

A host organism in which a pathogen lives and reproduces, serving as a source of infection for other species.

Define a vector in viral spread.

An organism that transmits a virus from a reservoir to another host.

Identify the reservoir and the vector for Zika virus in the notes.

Reservoir: macaques; Vector: mosquitoes.

List five common modes of viral transmission.

Respiratory droplets, aerosols, vectors, bodily fluids, and fomites.

Give two examples of fomites.

Clothes, utensils, furniture, door handles, etc. (any two).

Name four factors that influence how widely a virus spreads in a population.

Population size, number of contagious days, number of contacts per infected person, probability of transmission per contact.

State two personal actions that help prevent viral spread.

Staying home while contagious and practicing distancing/hand-washing.

What is an epidemic?

An outbreak affecting a specific community or region during a particular time.

What is a pandemic?

A disease outbreak that spans several countries or continents and affects a large proportion of the population.

When did COVID-19 transition from epidemic to pandemic?

March 2020, when it spread worldwide.

How does the animal immune system protect against future viral infections?

By producing antibodies that recognize and neutralize the same virus upon re-exposure.

What is the purpose of vaccines in viral disease prevention?

They expose the immune system to antigens so antibodies develop without causing illness.

Why are antiviral drugs less common than antibiotics?

Fewer effective antivirals exist and many have harsh side effects.

Order the biological levels of organization from smallest to largest.

Cells → Tissue → Organ → Organ system → Organism.

Define homeostasis.

The process by which organisms maintain a relatively stable internal environment.

Give one cellular example of homeostasis.

Osmosis balancing water/salt concentrations across the cell membrane.

How many major organ systems are in the human body, and name three of them.

Eleven; examples include cardiovascular, respiratory, digestive, nervous, etc. (any three).

What is negative feedback in physiological regulation?

A response that decreases or counteracts a change to restore balance.

What is positive feedback in physiological regulation?

A response that amplifies or increases a change in the system.

Which two body systems are primarily responsible for overall regulation?

Nervous system and endocrine system.

List four physiological variables regulated through negative feedback.

Body temperature, blood sugar, blood water levels, blood gas levels (O2/CO2).

Which body systems work together for nutrient absorption?

Digestive, circulatory, endocrine, and excretory systems.

Which hormone-producing system coordinates mating season and gamete production?

The endocrine system (with reproductive systems).

Name two structures that help defend the body from external injury.

Skin (integumentary) and skeletal system (bones protecting organs).

Where are many immune white blood cells produced?

In the bone marrow of the skeletal system.

State four distinctive features of a typical plant cell.

Cell wall (cellulose), large central vacuole, chloroplasts, eukaryotic structure.

What is the overall purpose of photosynthesis?

To convert light energy into chemical energy stored in glucose.

Name two polymers plants can build from glucose monomers.

Starches (energy storage) and cellulose (cell wall).

Differentiate angiosperms and gymnosperms.

Angiosperms are flowering plants with seeds in fruit; gymnosperms are non-flowering plants with seeds in cones.

What are the main functions of the root system in vascular plants?

Absorbing water/minerals, anchoring the plant, and storing sugars.

How do root hairs enhance absorption?

They increase surface area of roots in contact with soil.

List the primary roles of leaves, stems, and flowers in the shoot system.

Leaves: photosynthesis and gas exchange; Stems: transport; Flowers: reproduction in angiosperms.

What does xylem transport and in which direction?

Water and minerals upward from roots.

What does phloem transport and in which direction?

Sugars (photosynthates) from leaves downward or to growing tissues.

Define tropism.

A directional growth response toward (positive) or away from (negative) an environmental stimulus.

What is positive geotropism and where is it seen?

Growth with gravity, seen in roots growing downward.

Explain how auxin causes phototropism.

Auxin accumulates on the shaded side, stimulating cell elongation there, so the shoot bends toward light.

What is hydrotropism?

Growth response to water; roots show positive hydrotropism by growing toward moisture.

Give an example of thigmotropism.

Climbing vines wrapping around a support when touched.

How does nastic movement differ from tropism?

It is a rapid, reversible movement in response to stimuli, not a permanent growth direction (e.g., Venus flytrap closing).