Question

Chapter 31

1.Identify each statement as TRUE or FALSE.

a.Fungi are more closely related to plants than to animals.

b.Fungi do not produce gametes.

c.Fungi have sex but do not have male or female genders.

d.In some fungi, plasmogamy may precede karyogamy by decades.

2.Which of the following ecological roles are played by some fungi? Choose all correct answers.

a.Decomposition

b.Predation

c.Mutualistic symbiont

d.Autotroph

Answer 1

Questions 1

Ans - a - FALSE, --- Fungi and animals are more closely related to one another than either group is to plants. This has been determined through molecular phylogenetic analyses. Fungal cells are organized into tube-like filaments called hyphae.

Ans - b - FALSE, ---

Organisms having zygotic meiosis are fundamentally haploid. Growth and mitotic cell divisions always involve haploid cells. These organisms produce gametes (sex cells equivalent to sperm and egg) via mitosis, since they themselves are already haploid. Gametes may be produced in a great variety of structures, but ultimately the gametes must come together, fuse and form a diploid zygote. The zygote never divides mitotically; instead it undergoes meiosis and the resulting cells are again haploid, thereby completing a full life cycle. The following are characteristic of zygotic meiosis:

1. 1. Haploid thallus (body)
   2. Gametes produced by mitotic divisions of previously haploid nuclei
   3. Gametes fuse to form a zygote (diploid product of gametic fusion)
   4. Zygote divides by meiosis without intervening mitotic divisions
   5. Products of meiosis develop into new haploid generation

GAMETANGIAL MEIOSIS

Organisms having gametangial meiosis are fundamentally diploid. Growth and mitotic cell divisions always involve diploid cells. These organisms produce gametes via meiosis, since, unlike their gametes, they themselves are diploid. Gametes are produced in structures called gametangia. Gametangia contain diploid cells (at least initially) but some or all of these undergo meiosis to form the gametes. The gametes ultimately fuse to form a zygote. The zygote, which is already diploid like its parents, never undergoes meiosis, but instead develops by mitotic divisions, thereby completing the full life cycle. Humans have this type of life cycle. The following are characteristic of gametangial meiosis:

1. 1. Diploid thallus
   2. Gametes produced by meiotic divisions of previously diploid cells
   3. Gametes fuse to form a zygote (diploid product of gametic fusion)
   4. Zygote divides by mitosis without intervening meiotic divisions
   5. Products of mitosis develop into new diploid generation
2. . Ans- c - TRUE.
3. Ans -d- TRUE

QUESTIONS 2 ,

Ans- a.

Key Points

• Aiding the survival of species from other kingdoms through the supply of nutrients, fungi play a major role as decomposers and recyclers in the wide variety of habitats in which they exist.
• Fungi provide a vital role in releasing scarce, yet biologically-essential elements, such as nitrogen and phosphorus, from decaying matter.
• Their mode of nutrition, which involves digestion before ingestion, allows fungi to degrade many large and insoluble molecules that would otherwise remain trapped in a habitat.

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