Seaweed Webquest
Why are seaweeds assigned to the Protista rather than Plantae?
They aren't classified with plants because they don't have a vascular system.
List, describe, and state the function of the four basic parts of a seaweed. Also, state the name for the entire seaweed body.
Holdfasts, attach them to the sea floor. The stalk or stem of a seaweed is called a stipe and its main function is to support the rest of the plant. Blades main function is to provide a large surface area for the absorption of sunlight. Floats or pneumatocysts help to keep the photosynthetic structures of the seaweed buoyant so they are able to absorb energy from the sun.
What are the most important ecological roles filled by seaweeds?
They are a food source and provide shelter for many marine creatures.
List several types of environmental stress seaweeds encounter.
They encounter the constant motion of ocean water exposes seaweeds to mechanical stress.They also are exposed to air and weather conditions. Seaweeds living in tidepools are exposed to changes in water temperature and salinity caused by these weather conditions.
Briefly describe sexual and asexual reproduction in seaweed.
Seaweeds can reproduce sexually, by the joining of specialized male and female reproductive cells, called gametes. They also reproduce asexually through fragmentation or division.
Upon what characteristic are seaweeds classified?
The green algae (Chlorophyta), the brown algae (Phaeophyta), and the red algae (Rhodophyta).
Table 1. Comparison of Green, Brown, and Red Algae
21 points, 1 pt. each cell
Algae Type
|
Brown
|
Green
|
Red
|
Division
| Phaeophyta | Chlorphyta | Rhodophyta |
Specific Example
| Egregia menziesii | Codium fragile | Chondracanthus exasperatus |
Form(s)
| Large and elaborate | Single celled, or small | simple and branched filaments, fleshy plants, and sheets. |
Pigment(s)
| light olive green or golden, to very dark brown | light olive green | they may appear purple, brown, green, or yellow |
Habitat(s)
| intertidal or shallow subtidal zone, | shallow intertidal zone | deeper waters than other algae. Red algae also grow in the intertidal zone. |
Human Uses
| sold as a fertilizer for terrestrial agriculture. | Some common species of green algae such as Ulva (sea lettuce), and Enteromorpha(green string lettuce) are used as food products. | Carrageenan is an important ingredient in toothpaste and many milk products, such as ice cream and chocolate milk |
Useful Substances
| Fucans are the slimy stuff found on kelps, and have potential medicinal uses. | Agar has many scientific applications in microbiology, biotechnology, and criminology, and is also used in the packaging of canned meats |
Access the Miracle website and answer the following questions about diatoms.
What are diatoms?
Diatoms are photosynthesising algae
To what division and class diatoms assigned?
Division Chrysophyta, Class Bacillariophyceae
What are the major characteristics of diatoms?
Diatoms are commonly between 20-200 microns in diameter or length. The cell may be solitary or colonial
Describe the life cycle of a diatom.
When a cell divides each new cell takes as its epitheca a valve of the parent frustule, and within ten to twenty minutes builds its own hypotheca; this process may occur between one and eight times per day.
List five human uses for diatoms.
Diatoms reduce high blood pressure, clean the human colin, lowers cholesterol, reduce one's weight, ad strengthen hair, nails, gums, and teeth.
Explain the role of diatoms in the carbon cycle.
They reduce the amount of CO2 in the air during photosynthesis.
