CLASS ELEVEN BIOLOGY CHAPTER 2 BIOLOGICAL CLASSIFICATION QUESTIONNAIRE PART 3
CLASS ELEVEN BIOLOGY CHAPTER 2 BIOLOGICAL CLASSIFICATION QUESTIONNAIRE FOR TESTS AND REVISION.
PART 3
A. Fungi are heterotrophic organisms that lack chlorophyll and cellulosic cell walls, unlike plants, and they do not have complex organ systems like animals.
1. What distinguishes fungi from plants and animals?
A. Examples include mushrooms, toadstools, mold on bread and fruits, and yeast used in baking and brewing.
2. Provide examples of common fungi found in everyday life.
A. Fungi are heterotrophs that absorb soluble organic matter from dead substrates. They secrete enzymes to break down complex organic molecules into simpler forms that can be absorbed through their hyphae.
3. How do fungi obtain nutrients?
A. Fungal bodies consist of long, slender thread-like structures called hyphae. These hyphae form networks known as mycelium, which may be either coenocytic (multinucleated) or septate (with cross walls).
4. Describe the structure of fungal bodies.
A. Fungal cell walls are composed of chitin, a polysaccharide, along with other polysaccharides like glucans.
5. What are the main components of fungal cell walls?
A. Fungi reproduce vegetatively through fragmentation, where hyphae break into fragments that can grow into new individuals. They also reproduce through fission (binary fission) and budding, where new cells or hyphae grow from the parent organism.
6. How do fungi reproduce vegetatively?
A. Conidia are asexual spores produced externally at the tips or sides of specialized hyphae called conidiophores. Sporangiospores are formed within sporangia, which are sac-like structures. Zoospores are flagellated spores capable of swimming through water.
7. What are conidia, sporangiospores, and zoospores in fungal reproduction?
A. Sexual reproduction in fungi involves:
8. Explain the process of sexual reproduction in fungi.
a. Plasmogamy: Fusion of cytoplasm between two compatible mating types (gametes).
b. Karyogamy: Fusion of nuclei from the fused gametes.
c. Meiosis: Reduction division in the zygote resulting in haploid spores (oospores, ascospores, or basidiospores).
A. In some fungi (ascomycetes and basidiomycetes), after plasmogamy, a dikaryotic phase (n + n, with two nuclei per cell) occurs. This stage, called the dikaryon, precedes fusion of nuclei to form diploid cells during karyogamy.
9. What is the significance of the dikaryotic phase in fungal sexual reproduction?
A. Yeast, a type of fungi, is used in baking to ferment dough and produce bread. It is also used in brewing to ferment sugars into alcohol to produce beer.
10. How do fungi contribute to food production?
A. Fungi such as Penicillium produce antibiotics like penicillin, which have been crucial in treating bacterial infections.
11. What role do fungi play in medicine?
A. Some fungi, like Puccinia, cause diseases in plants (e.g., wheat rust), affecting agricultural productivity.
12. How do fungi impact agriculture?
A. Lichens are symbiotic associations between fungi and algae or cyanobacteria. The fungal partner provides structure and protection, while the algal or cyanobacterial partner performs photosynthesis to produce food.
13. What are lichens, and how do they form?
A. Mycorrhizal fungi form symbiotic associations with plant roots, enhancing the plant's ability to absorb water and nutrients from the soil in exchange for carbohydrates produced by the plant through photosynthesis.
14. How do mycorrhizal fungi benefit plants?
A. Fungi prefer warm and humid environments, as these conditions promote their growth and reproductive activities.
15. What environmental conditions do fungi prefer for growth?
A. Fungi can cause diseases in animals by infecting their skin, respiratory tract, or internal organs. Examples include ringworm and histoplasmosis.
16. How do fungi cause diseases in animals?
A. Parasitic fungi affecting plants include powdery mildews, which cause white spots on leaves, and rust fungi like Puccinia, which cause rust-like lesions on plant tissues.
17. What are some examples of parasitic fungi affecting plants?
A. Fungi adapt to diverse habitats by producing spores that can withstand harsh environmental conditions and by forming symbiotic relationships that enhance their survival in specific ecosystems.
18. How do fungi adapt to diverse habitats?
A. Saprophytic fungi decompose dead organic matter, breaking down complex molecules into simpler forms and returning nutrients to the soil, which promotes nutrient cycling in ecosystems.
19. Describe the ecological role of saprophytic fungi.
A. Fungi are economically important for food production (e.g., mushrooms, yeast), medicine (e.g., antibiotics), bioremediation (e.g., breaking down pollutants), and agriculture (e.g., mycorrhizal fungi).
20. What are the economic uses of fungi?
A. Fungi can cause diseases in humans, such as respiratory infections (e.g., aspergillosis), skin infections (e.g., athlete's foot), and systemic infections (e.g., candidiasis).
21. How do fungi impact human health?
A. The fruiting body of a mushroom typically consists of a cap (pileus) supported by a stalk (stipe) and contains gills or pores underneath where spores are produced.
22. What are the characteristics of a mushroom's fruiting body?
A. Fungi spread their spores through various means, including air currents, water, animals, and human activities. Some fungi have specialized structures or mechanisms for spore dispersal.
23. How do fungi spread their spores?
A. Chitin provides structural support and protection to fungal cells, similar to its role in the exoskeletons of arthropods.
24. What is the importance of chitin in fungal cell walls?
A. Fungi form symbiotic relationships with algae (as lichens) and plant roots (as mycorrhizae), where they exchange nutrients and enhance the survival and growth of their partners.
25. How do fungi interact with other organisms in symbiotic relationships?
A. Fragmentation allows fungi to reproduce vegetatively by breaking hyphae into fragments that can grow into new individuals under suitable environmental conditions.
26. How does fragmentation contribute to fungal reproduction?
A. Fungal diseases in plants can reduce crop yields, affect biodiversity, and disrupt ecosystems by altering nutrient cycling and plant community dynamics.
27. What are the ecological implications of fungal diseases in plants?
A. Yeast cells are unicellular fungi that reproduce by budding, unlike most fungi that are filamentous (multicellular) and reproduce by forming spores.
28. Why are yeast cells considered exceptions among fungi?
A. Septate hyphae have cross walls (septa) that divide the hyphae into individual cells, each containing one or more nuclei. Coenocytic hyphae lack these septa, forming continuous multinucleated tubes.
29. How do septate hyphae differ from coenocytic hyphae?
A. The formation of fruiting bodies in fungi is influenced by environmental factors such as temperature, humidity, and nutrient availability, as well as genetic factors related to fungal species and life cycle stages.
30. What factors influence the formation of fruiting bodies in fungi?
A. Members of Phycomycetes are found in aquatic habitats, on decaying wood in moist and damp places, or as obligate parasites on plants.
31. Where are members of Phycomycetes typically found?
A. The mycelium of Phycomycetes is aseptate and coenocytic, meaning it lacks cross walls (septa) and consists of continuous multinucleated tubes.
32. Describe the structure of the mycelium in Phycomycetes.
A. Asexual reproduction in Phycomycetes occurs by zoospores (motile spores) or aplanospores (non-motile spores) that are endogenously produced within sporangia.
33. How does asexual reproduction occur in Phycomycetes?
A. Sporangia are specialized structures within which zoospores or aplanospores are produced endogenously by Phycomycetes.
34. What are sporangia in Phycomycetes?
A. A zygospore is a thick-walled structure formed by the fusion of two gametes. In Phycomycetes, these gametes can be similar in morphology (isogamous) or dissimilar (anisogamous or oogamous).
35. What is a zygospore, and how is it formed in Phycomycetes?
A. Common examples include Mucor (Figure 2.5a), Rhizopus (commonly known as bread mold), and Albugo (a parasitic fungus affecting mustard plants).
36. Provide examples of common Phycomycetes organisms.
A. Phycomycetes play roles as decomposers of organic matter in aquatic environments and on decaying wood, as well as pathogens causing diseases in plants.
37. What is the ecological role of Phycomycetes in their habitats?
A. Zoospores are motile spores that allow Phycomycetes to disperse and colonize new environments, facilitating their reproductive success.
38. How do zoospores contribute to the life cycle of Phycomycetes?
A. Isogamous gametes are morphologically similar and fuse to form a zygospore. Anisogamous gametes are morphologically different but still fuse to form a zygospore. Oogamous gametes involve a large, non-motile egg cell (female) and a smaller, motile sperm cell (male) that fertilize to form a zygospore.
39. Compare and contrast isogamous, anisogamous, and oogamous gametes in Phycomycetes.
A. Phycomycetes adapt to different environments through their ability to produce diverse types of spores and by forming specialized structures like sporangia for efficient reproduction and survival.
40. How do Phycomycetes adapt to their varied environments?
A. Phycomycetes can cause diseases in crops, affecting agricultural productivity, and contribute to the decomposition of organic matter, which is essential for nutrient cycling in ecosystems.
41. What are some economic impacts of Phycomycetes?
A. Phycomycetes interact with other organisms as decomposers, pathogens of plants, and contributors to nutrient cycling in aquatic and terrestrial ecosystems.
42. How do Phycomycetes interact with other organisms in their ecosystems?
43. Explain the significance of coenocytic hyphae in Phycomycetes.
A. Coenocytic
hyphae in Phycomycetes allow for rapid growth and nutrient transport throughout
the mycelium, enhancing their ability to colonize substrates and obtain
resources.
A. Coenocytic hyphae in Phycomycetes allow for rapid growth and nutrient transport throughout the mycelium, enhancing their ability to colonize substrates and obtain resources.
A. Phycomycetes thrive in moist, damp environments with sufficient organic matter for decomposition, such as aquatic habitats, decaying wood, and areas with high humidity.
44. What environmental conditions favor the growth of Phycomycetes?
A. Phycomycetes typically reproduce using motile zoospores and non-motile aplanospores, whereas other fungal groups may use different types of spores and reproductive structures like ascospores and basidiospores.
45. How do Phycomycetes differ from other fungal groups in terms of reproductive strategies?
A. Mucor reproduces asexually by producing sporangia containing sporangiospores within its mycelium. Sexual reproduction occurs through the fusion of isogamous or anisogamous gametes to form a zygospore.
46. Describe the life cycle of Mucor as an example of a Phycomycete.
A. Phycomycetes secrete enzymes that break down complex organic molecules into simpler forms, facilitating the decomposition of dead plant and animal material.
47. How do Phycomycetes contribute to the decomposition of organic matter?
A. Sporangia are specialized structures that protect and release spores (zoospores or aplanospores) for dispersal, enabling the spread and reproduction of Phycomycetes.
48. What roles do sporangia play in the life cycle of Phycomycetes?
A. Phycomycetes play crucial roles in nutrient cycling and food webs within aquatic ecosystems by decomposing organic matter and serving as food sources for other organisms.
49. How are Phycomycetes important in aquatic ecosystems?
A. Coenocytic hyphae allow for efficient nutrient uptake and distribution throughout the mycelium, enhancing the competitive advantage and survival of Phycomycetes in diverse environments.
50. How does the presence of coenocytic hyphae benefit Phycomycetes in their habitats?
A. Rhizopus, commonly known as bread mold, thrives on decaying bread and other starchy materials, contributing to the decomposition process in human-influenced environments.
51. What distinguishes Rhizopus from other Phycomycetes in terms of its ecological niche?
A. Phycomycetes like Albugo can cause diseases in plants, leading to reduced crop yields and economic losses in agriculture.
52. How do Phycomycetes impact the health of plants?
A. Phycomycetes have specialized structures and reproductive strategies that enable them to infect and colonize host plants, extracting nutrients and causing disease symptoms.
53. What adaptations do Phycomycetes exhibit for parasitic lifestyles?
A. Zoospores are motile and equipped with flagella, allowing them to swim through water to find suitable substrates for germination and colonization. Aplanospores, in contrast, are non-motile and rely on environmental factors for dispersal.
54. How do zoospores of Phycomycetes differ from aplanospores in terms of mobility and function?
A. Phycomycetes represent an ancient lineage of fungi with diverse reproductive strategies and ecological adaptations, providing insights into the evolution and diversification of fungal species over geological time scales.
55. How can the study of Phycomycetes contribute to understanding fungal evolution?
A. Environmental factors such as temperature, humidity, and nutrient availability influence the production and release of zoospores from sporangia in Phycomycetes, affecting their dispersal and reproductive success.
56. What environmental factors influence the formation and release of zoospores in Phycomycetes?
A. Phycomycetes like Mucor are used in biotechnology for enzyme production and as model organisms for studying fungal genetics and physiology in laboratory settings.
57. How are Phycomycetes utilized in biotechnology and research?
A. Diseases caused by Phycomycetes in crops can lead to significant yield losses and increased costs for disease management, impacting agricultural economies and food security.
58. What are the economic consequences of diseases caused by Phycomycetes in agriculture?
A. Phycomycetes decompose organic matter, releasing nutrients like nitrogen and phosphorus into the soil, which are essential for plant growth and ecosystem productivity.
59. How do Phycomycetes contribute to nutrient cycling in terrestrial ecosystems?
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