Question

Please answer each question the questions are in reference to ravens plant biology

1. Introduction; pp. 317–320; moderate

Explain some of the problems faced by evolutionary biologists when trying to define “protist.”

2. Ecology of the Algae; pp. 320–322; moderate

Discuss some of the roles played by algae in ecosystems around the world.

3. Euglenoids; p. 324; moderate

Describe the distinctive cellular features of the euglenoids.

4. Cryptomonads: Phylum Cryptophyta; pp. 324–325; moderate

Is a cryptomonad one organism or two? Explain your answer.

Answer 1

1. Protista exhibits characteristics which are very diverse and possess resemblance with multiple kingdoms. Some of them are parasitic while others are predators, whereas others are producers. Hence some of the scientists place them in plants kingdom. Some of them have cell wall while others have a fragile membrane.  For example, Euglena has both plant-like and animal-like characteristics. It have chloroplasts like plant and at the same time, they have a flagellum for swimming, giving animal-like characteristic.

2. Algae play a very important role in the food web. For example, phytoplankton act as the foundation of the ocean food web. They are an important producer in the ocean and hence their proportion in the ocean is important. They also support the proliferation of other oceanic species by providing safe habitats for them. They play an important role in determining the earth's climate. When algal tissues are damaged, they release dimethylsulfonioproprionate (DMSP) which is essential for the biogeochemical cycles of the earth which are broken down to dimethyl sulfide (DMS). DMS diffuses into the air and oxidizes to form sulfate aerosols. Water attaches to from clouds hence helps to determine the earth's climate.

3. Euglenoids are unicellular organism containing cell membrane rich in protein called pellicle. They usually have two flagella present which are of unequal sizes. Paramylon granules are present which act as the food storage organelles. They have carotenoids and have chlorophyll A and B present in the thylakoids. They have light-sensitive spots named stigma which helps in light detection.

4. Cryptomonads are a group of algae which are mostly found in freshwater.