BIO 121 - Ch 9: Fungi and Plants

What was a major milestone in the evolution of life?

The origin of multicellular life.

What have biologists proposed about the evolution of multicellular organisms?

Biologists have hypothesized a series of steps that may have occurred in the evolution of multicellularity.

What type of organism likely came before multicellular life?

A unicellular protist

What is a colony in the context of multicellularity?

It is a loose physical association of individual free-living cells.

What type of organisms are fungi?

Fungi are a diverse group of eukaryotes.

Approximately how many species of fungi have been identified?

There are over 100,000 identified species.

What important role do fungi play in ecosystems?

It decomposes dead organisms.

What is a decomposer?

It is an organism that breaks down large molecules into smaller molecules and absorbs them.

Why are decomposers important for the environment?

Because they recycle nutrients back into the environment.

What is found in fungal cell walls?

chitin

What is the function of chitin in fungal cell walls?

It uses chitin for strength.

What type of molecule is chitin?

It is a strong but flexible polysaccharide, similar to cellulose.

How does chitin compare to cellulose?

Both are strong structural polysaccharides, but chitin is found in fungi, while cellulose is found in plants.

Where else is chitin found besides fungal cell walls?

It also makes up the hard exoskeleton of many insects.

What are the main structural parts of multicellular fungi?

It consist of aboveground and belowground structures.

What is the function of the aboveground structures in fungi?

Aboveground, mushrooms produce spores for reproduction.

What is the function of the belowground part of fungi?

Belowground, consist of mycelium, that digests food.

What are hyphae?

It is filaments made up of cells arranged end to end.

What is a mycelium?

It is a mass of filaments that make up the body of a multicellular fungus.

What are spores?

They are reproductive cells that can produce new mycellium.

How do fungi usually reproduce?

asexually, without sex

How do single-celled yeasts reproduce?

asexually by budding

What is budding?

It is a form of asexual reproduction where a new organism grows out of the parent organism.

Where are spores produced in some fungi?

In specialized cells on the underside of the mushroom cap.

What type of chromosomes do these spores contain on the underside of the mushroom cap?

A single (haploid) set of chromosomes.

Less commonly, fungi reproduce….

sexually

How can some fungi begin sexual reproduction?

By joining hyphae to form diploid cells.

What happens after diploid cells are formed in fungi?

The diploid cells divide to produce genetically distinct haploid spores.

There is a wide variety of fungi, both…

helpful and harmful

What organism is considered the largest individual organism in the world by area?

A fungus is the largest individual organism in the world by area.

Where is the largest known fungus located?

Malheur National Forest in eastern Oregon.

What structure allows this fungus to cover such a large area?

An underground mycelium covering 2,200 acres (3.5 square miles or 9.1 km2).

How old is this giant fungus estimated to be?

8,000 years old

How much does the largest fungus possibly weigh?

as much as 35,000 tons

What type of organism is responsible for ergotism in cereal grains?

A sac fungus infects cereal grains and produces a toxin.

What is ergotism?

It is a type of food poisoning caused by toxins produced by a fungus that infects cereal grains.

What symptoms are associated with ergotism?

Hallucinations, hysteria, and convulsions.

Why might fungi be historically linked to witchcraft?

Because toxins from fungi (like those causing ergotism) can cause hallucinations and unusual behavior, which may have been interpreted as witchcraft.

What is a plant pathogen?

It is an organism that causes disease in plants.

Plants are …….. with unique adaptations for survival on land.

eukaryotes

When did ancestral plants begin to evolve from sea-dwelling algae?

Around 500 million years ago.

From what type of organisms did plants evolve?

Sea-dwelling algae

What is a plant?

It is a terrestrial, multicellular eukaryote that conducts photosynthesis.

What happens during photosynthesis in plants?

Plants convert inorganic molecules into organic molecules.

What allows plants to thrive on land?

Structural adaptations that allow them to gain resources from air and soil.

What is the shoot system?

It consists of photosynthetic structures exposed to light and air aboveground.

What is the root system?

It anchors the plant and absorbs water and minerals from the soil belowground.

How do the shoot system and root system work together?

The shoot system captures light and air for photosynthesis, while the root system provides water and minerals, allowing the plant to survive and grow.

What is the role of pollen in plants?

It protects sperm and allows it to be carried by wind or animals.

How does the egg in plants contribute to reproduction?

It remains in the female reproductive organ, allowing the embryo to develop within the mother plant’s body.

What is the vascular system in plants?

It is a network of tubes that transports water, sugars, and minerals.

What is the cuticle?

It is a waxy coating on plant surfaces that prevents water loss.

What is the main function of leaves?

It is the main site of photosynthesis and gas exchange through pores.

What is lignin and what does it do?

It is a chemical in cell walls that stiffens them, increasing structural support.

How are the evolution of plants and fungi related?

They are interconnected.

What is a mycorrhizae?

It is a symbiotic association between fungi and plant roots.

What does the fungus provide to the plant in a mycorrhizal relationship?

Water and minerals absorbed from the soil

What does the plant provide to the fungus in a mycorrhizal relationship?

Sugars as nourishment