Chapter 19.3, Problem 3MI

Summary Introduction

To define:

The given words using a book or a dictionary and then use each term in a sentence to explain its scientific meaning

Introduction:

Algae are plant like protists that are autotrophic and are producers for the aquatic ecosystems. Algae contain photosynthetic pigment chlorophyll due to which they can produce food through the process of photosynthesis. Some algae also contain secondary pigments that allow them to absorb light from wavelengths that are not absorbed by water. Because of these pigments algae are found in a variety of colors.

Answer to Problem 3MI

Bioluminescent- Any living thing that emits light is called bioluminescent.

Some algae that are members of the phylum Pyrrophyta such as the dinoflagellates are bioluminescent, that is they emit light.

Colony- A group of cells that join together to form a close association is called a colony.

Volvox is a green alga that forms a colony as it is composed of hundreds and thousands of cells.

Alternation of generations- Life cycle of some organisms involve two generations- one that reproduces sexually and the other that reproduces asexually.

Ulva, a multicellular green alga, shows alternation of generations in which the generations alternate between haploid gametophyte and diploid sporophyte.

Explanation of Solution

Bioluminescent- Dinoflagellates that emits light are bioluminescent. Dinoflagellates are alga with thick cellulose cell walls. They come in variety of shapes and styles- some resemble helmets and some look like armor. They contain chlorophyll, red pigments and carotenes. Some live in freshwater and some are marine. Many species live in symbiosis with jelly fishes, corals and mollusks while some free living species emit light. These light emitting algae are called bioluminescent. Colony- Green algae can be unicellular or multicellular or colonial in organization. A colony is a group of cells that live together in close association. A Volvox colony is made of hundreds and thousands of flagellated cells arranged in a single layer forming a hollow ball shaped structure. The cells are connected by strands of cytoplasm and the flagella of individual cells face outward. The flagella can beat in coordinated fashion to spin the colony through water. Small balls of daughter colonies are formed inside the large ball.

Alternation of generation- The life cycles of some algae and all plants have a pattern called alternation of generations. An organism with this life cycle alternates between a haploid and a diploid stage creating two generations. The haploid form is called gametophyte and the diploid form is called sporophyte. This is a complex life cycle.