Algae

Question 1

What are algae?

Answer 1

Photosynthetic organisms, mostly aquatic, ranging from unicellular to large seaweeds. Belong to the kingdom Protista.

Question 2

What is a thallus?

Answer 2

The body of algae, lacking true roots, stems, or leaves. Can be unicellular or multicellular.

Question 3

How do algae reproduce asexually?

Answer 3

By cell division, fragmentation, or spores like monospores, aplanospores, and zoospores.

Question 4

How do algae reproduce sexually?

Answer 4

By forming gametes (egg and sperm) that fuse to form a zygote, which forms zoospores and undergoes meiosis.

Question 5

What are the plant-like parts of some algae?

Answer 5

Holdfast (roots)

Stipe (stem-like)

Blades (leaf-like)

Pneumatocyst (air bladder for buoyancy)

Question 6

What is the function of a pneumatocyst?

Answer 6

A gas-filled bladder that helps algae float to reach sunlight.

Question 7

Name three phyla of algae and a key trait for each.

Answer 7

Chlorophyta (green algae) – store starch, have chlorophyll a & b

Phaeophyta (brown algae) – have fucoxanthin pigment

Rhodophyta (red algae) – contain phycobilins and live in deep waters

Question 8

What causes harmful algal blooms (HABs)?

Answer 8

Excess nutrients from pollution lead to rapid algae growth, causing oxygen loss and toxins that harm marine life.

Question 9

What is haptera/holdfast

Answer 9

is a structure that anchors the alga to a substrate

Question 10

Chlorophyta (Green Algae)

Answer 10

Common green algae, ~7,000 species
Contain chlorophyll a & b, carotenoids
Cell wall: Mostly cellulose; sometimes calcium carbonate
Food storage: Starch
Found in freshwater, marine, and moist areas
Examples: Ulva, Spirogyra, Chlamydomonas

Question 11

Phaeophyta (Brown Algae)

Answer 11

Largest protists (~1,500 species)
Contain chlorophyll a & c, fucoxanthin (brown pigment)
Food storage: Laminarin
Found in cool marine waters
Adaptations: Holdfasts, stipes, air bladders
Examples: Laminaria, Fucus

Question 12

Rhodophyta (Red Algae)

Answer 12

Red algae, ~4,000 species
Contain chlorophyll a and phycobilins (red pigment)
Food storage: Starch
Cell wall: Cellulose, agar, sometimes carrageenan
Found in warm marine & deeper waters, sometimes freshwater
Used in culture media and medicine capsules

Question 13

Bacillariophyta (Diatoms)

Answer 13

Also known as diatoms, ~11,500 species
Contain chlorophyll a & c, carotenoids, xanthophylls
Food storage: Starch
Cell wall: Cellulose + silica (SiO₂); glass-like shell
Major component of phytoplankton; starts many food chains

Question 14

Dinoflagellata (Pyrrophyta)

Answer 14

Also called pyrrophyta, ~1,100 species
Contain chlorophyll a & c, carotenoids
Unicellular, mostly marine plankton
Food storage: Starch
Can cause red tides; produce toxins

Question 15

Chrysophyta (Golden Algae)

Answer 15

Also called golden algae, ~850 species
Contain chlorophyll a & c, fucoxanthin, carotenoids
Mostly found in freshwater
Can form resistant cysts to survive in frozen lakes

Question 16

Euglenophyta (Euglenoids)

Answer 16

Unicellular, ~1,000 species
Contain chlorophyll a & b, carotenoids
No cell wall, but have a flexible pellicle (protein covering)
Live in freshwater, moist soil, or animal intestines
Food storage: Paramylon (a type of polysaccharide)