Phaeophyta, Rhodophyta and Xanthophyta

Question 1

receptacles

Explain the reproductive process of Fucus in Phaeophyta, including both gametogenesis and fertilization.

Answer 1

Fucus have flattened, porous reproductive structures called receptacles that open into hollow chamber called conceptacles that contain the gametangia.

Sexual reproduction is oogamous and involves sperms produced by antheridium in the male receptacles and eggs produced by oogonium in the female receptacles.

Eight eggs are produced in the oogonium as a result of a single diploid undergoing meiosis then mitosis. 64 sperms are usually produced in the antheridium as a result of meiosis followed by 4 mitotic divisions.

The two fuse during fertilization in the water to
form a diploid zygote.

In suitable conditions, the zygote develops into a mature diploid thallus.

Question 2

Describe the detailed structure of the thallus in Phaeophyta, emphasizing the role of the holdfast, stipe, and blades. How do these components contribute to the algae’s survival in marine environments?

Answer 2

The thallus is differentiated into:
1. Holdfast - joins seaweed to soil. Provides support.
2. Stipe - connects the holdfast to leaf-like blades
3. Blades - have photosynthetic tissue to carry out phottosynthesis and provide food for organisms.
4. Bladder - gas-filled floater

Question 3

List and explain the different pigments found in Phaeophyta and their roles in photosynthesis. How do these pigments enhance the algae’s ability to thrive in deep waters?

Answer 3

fucoxanthin, chlorophyll a and c

Question 4

Provide examples of Phaeophyta species and discuss their ecological roles in marine ecosystems.

Answer 4

Fucus, Macrocystis, Nereocystis and Sargassum

Question 5

alternates diploid and haploid, the role of meiosis and fertilization.

Outline the complete life cycle of Fucus in Phaeophyta, focusing on its reproductive strategy and alternation of generations.

Answer 5

• the plant body of the Fucus is diploid in nature and produces haploid gametes.
• The Fucus may have separate male and female thallus or both sexes on the same thallus.
• The reproductive structures are the flattened, porous receptacles located at the tips of ___. __The receptacles are connected to hollow chamber called conceptacles where there are gametangia.
• The oogonium produces a single diploid nucleus which divides meiotically and then mitotically to give 8 egg cells.
• The antheridium produces 64 sperms from single diploid nucleus which undergoes meiosis then 4 miotic divisions.
• The sex cells eventually fuse during fertilization in water to give rise to a diploid zygote.
• Under suitable conditions, the zygote develops into a mature, diploid plant.
• This completes the life cycle of the plant.

Question 6

role of gametophytes, carposporophytes, and tetrasporophytes

Describe the life cycle of Polysiphonia, a representative of Rhodophyta, focusing on its reproductive phases and the alternation of generations.

Answer 6

-

Question 7

What is the primary food reserve of Rhodophytes and how does it function in their metabolism?

Answer 7

floridean starch as the primary reserve is a carbohydrate broken down during metabolism to yield energy for physiochemical processes.

Question 8

List and explain three general characteristics of Rhodophytes that distinguish them from other algae groups.

Answer 8

their pigmentation (phycobilins), the absence of motile reproductive cells, and their predominantly filamentous or branched structures.

Question 9

What is the primary pigment found in diatoms?

Question 10

Which structure in brown algae resembles intertwined roots?

Answer 10

the holdfast which connects the seaweed to the soil.

Question 11

Name the two main types of diatoms based on their symmetry.

Question 12

What is the primary storage form of carbohydrates in diatoms?

Question 13

Compare and contrast the epitheca and hypotheca in diatom cell structure.

Question 14

Explain why diatom walls persist after the death of protoplasts.

Question 15

Describe the basic structure of brown algae thallus and its main components.

Answer 15

The thallus is differentiated into :
1. The holdfast - connects seaweed to soil; provides support
2. The stipe - connects holdfast to blades
3. The bladder - gas-filled to enable floating of blades
4. The blades - photosynthetic leaf-like structures

Question 16

What role does silica play in diatom cell wall composition?

Question 17

What role does silica play in diatom cell wall composition?

Question 18

Diagram and explain the process of sperm cell formation through successive mitosis as shown in the content.

Question 19

How do the structural features of diatoms contribute to their survival?

Question 20

Analyze the evolutionary significance of silica-based cell walls in diatoms.

Question 21

Compare the reproductive strategies between brown algae and diatoms based on the provided information.

Question 22

Evaluate the ecological importance of brown algae as marine organisms.

Question 23

How does the presence of fucoxanthin and other pigments affect the photosynthetic efficiency of diatoms?

Question 24

Discuss the potential applications of diatom-based materials in sustainable technology.

Question 25

Analyze the ecological significance of brown algae in marine ecosystems, discussing their structural adaptations and role in marine food webs.

Question 26

Compare and contrast the cellular organization and wall structure of diatoms with other algal groups, explaining how these features contribute to their success in aquatic environments.

Question 27

Evaluate the reproductive strategies in brown algae and diatoms, discussing how these mechanisms ensure species survival and genetic diversity.

Question 28

Discuss the potential impacts of climate change and ocean acidification on brown algae communities and their ecological implications.

Question 29

Analyze the biotechnological applications of brown algae and diatoms in modern industry, focusing on their unique structural and biochemical properties.