7.7 Protists 2 Lecture Pt.1

Flashcards cover taxonomy, structures, life cycles, ecology, and diseases of protists discussed in the lecture.

What cellular extensions do amoebas use for movement and feeding?

Pseudopodia ("false feet")

How do amoebas obtain nutrients?

By phagocytosis—engulfing food particles

Why do freshwater amoebas and other protists need a contractile vacuole?

For osmoregulation; it expels excess water that diffuses into the cell

The so-called “brain-eating amoeba” (Naegleria fowleri) actually belongs to which supergroup?

Excavata, not true Amoebozoa

What morphological feature gives the supergroup Excavata its name?

A pronounced ventral feeding groove

How many flagella are typical of Euglena?

One long anterior flagellum (sometimes an internal second)

What flexible protein layer replaces a rigid cell wall in Euglena?

The pellicle, made of protein strips

What light-sensitive organelle helps Euglena orient toward light?

A red eyespot (stigma)

When nutrients are scarce, how can Euglena shift its nutrition?

It switches from autotrophic photosynthesis to heterotrophic ingestion

Which endosymbiotic event produced the plastids of brown algae and diatoms?

Secondary endosymbiosis

What two flagella arrangement characterizes dinoflagellates?

One transverse and one longitudinal flagellum, causing a spinning motion

What protective covering do dinoflagellates possess?

Cellulose armor plates (theca)

Why do many dinoflagellates glow when disturbed at night?

They are bioluminescent as an anti-predator response

What name is given to symbiotic dinoflagellates living in coral tissues?

Zooxanthellae

What happens during coral bleaching?

Stressed corals expel their zooxanthellae, losing color and vital nutrients

What causes toxic “red tides”?

Massive blooms of toxin-producing dinoflagellates

What locomotory organelles cover ciliates such as Paramecium?

Numerous short cilia

How many kinds of nuclei do ciliates have?

Two: a macronucleus and a micronucleus

Through what sexual process do Paramecium exchange genetic material?

Conjugation

Which protist lineage is defined by gametes bearing a “hairy” flagellum?

Stramenopiles

Name two photosynthetic stramenopile groups discussed in lecture.

Brown algae and diatoms

Which pigment gives brown algae their characteristic color?

Fucoxanthin, a brown carotenoid

List three main parts of a kelp thallus.

Blade, stipe, and holdfast (plus air bladders for buoyancy)

What ecological role do kelp forests play?

They are foundation species providing habitat and food for diverse marine life

Of what mineral are diatom frustules composed?

Silica (hydrated silicon dioxide)

What commercially mined substance is formed from fossil diatom shells?

Diatomaceous earth (used as abrasives, filters, pesticides)

Roughly what fraction of Earth’s oxygen is produced by phytoplankton such as diatoms?

About 50 %

Which red pigment allows red algae to photosynthesize in deep water?

Phycoerythrin

What storage carbohydrate do green algae share with land plants?

Starch

Which green-algal group is sister to land plants?

Charophytes (charophycean algae)

Give an example of a colonial green alga.

Volvox

Which filamentous green alga reproduces by conjugation?

Spirogyra

In a zygotic-meiosis (haploid-dominant) life cycle, which stage is diploid?

Only the zygote

During haploid-dominant cycles, are gametes produced by mitosis or meiosis?

Mitosis

What life-cycle type do animals exhibit?

Gametic meiosis (diploid-dominant)

In a diploid-dominant life cycle, what process directly produces gametes?

Meiosis

Name the two generations that alternate in a sporic life cycle.

Sporophyte (2n) and gametophyte (n)

In alternation of generations, meiosis produces ___; mitosis produces ___.

Meiosis produces haploid spores; mitosis produces gametes

The large visible kelp plant is which generation?

The diploid sporophyte

What structures on a kelp blade release spores?

Sporangia

Which water mold caused the 19th-century Irish potato famine?

Phytophthora infestans

What intestinal disease is caused by Giardia intestinalis?

“Beaver fever” or backpacker’s diarrhea, contracted from contaminated water

Which protist genus causes malaria?

Plasmodium

What insect vector transmits Plasmodium to humans?

The Anopheles mosquito

Trypanosoma brucei causes African sleeping sickness; what vector spreads it?

The tsetse fly

Why do freshwater protists without cell walls rely on contractile vacuoles?

To pump out water continually entering by osmosis

Cellulose-based cell walls evolved independently in green and brown algae. What evolutionary term describes this?

Convergent evolution

Define phytoplankton.

Drifting microscopic photosynthetic organisms that form the base of aquatic food webs

Give two human uses of macroalgae mentioned in lecture.

Edible seaweeds (e.g., nori, sea lettuce) and nutritional delicacies