Quiz 7 (Tuesday Morning)

 

  1. The number of nuclei in a mature embryo sac (female or mega-gametophyte) is 8

 

  1. Why is fertilization in the flowering plants referred to as “double” fertilization?

 

Because the polar nuclei are fertilized as well as the egg by the two sperms.

 

  1. When pollen grains are dispersed from a flower, are their nuclei haploid or diploid?  How do you know?

 

Pollen grains are microgametophytes,and all gametophytes are haploid.

 

  1. What is the difference between a diploid cell and a dikaryotic cell?

 

A diploid cell contains a nucleus with two sets of  chromosomes.  A dikaryotic cell contains two haploid nuclei.

 

  1. What is an advantage of aseptate hyphae in the Zygomycota?

 

Fast transport of nutrients throughout the mycelium

 

  1. How are basidia and asci similar?

 

They are sporangia within which meiosis produces meiospores.

 

Quiz 7 (Tuesday Afternoon)

 

 

  1. How many nuclei are in a germinated pollen grain (male or microgametophyte) just before fertilization?  3

 

  1. Why is endosperm triploid?

 

Because it arises from the fusion of two polar nuclei (both haploid) and a sperm (haploid)

 

  1. In which of the following parts of a flower does meiosis take place: sepals, petals, anthers, ovules?

 

Only in the anthers and ovules

 

  1. Which nuclei undergo meiosis in a fungus?

 

Only the zygote resulting from karyogamy

 

  1. What is a disadvantage of septate hyphae in Ascomycota and Basidiomycota?

 

Transport of nutrients is slowed, resulting in lower growth rates compared to Zygomycota.

 

  1. What types of nuclear division produce basidiospores and conidia? Meiosis.

 

Quiz 7 (Thursday Morning)

 

  1. What is the difference between a megasporocyte and a megaspore?

 

A megaspore results from meiosis of a megasporocyte

 

  1. Why are embryos diploid?

 

Because they result from fusion of two haploid nuclei (of an egg and a sperm)

 

  1. Which stage of the angiosperm life cycle is structurally more complex, the sporophyte or the gametophyte?  Explain your answer.

 

The sporophyte.  Angiosperm gametophytes are microscopic, consisting of only a few cells.

 

  1. What is a the difference between fungal plasmogamy and karyogamy?

 

Plasmogamy = fusion of hyphae.  Karyogamy = fusion of nuclei.

 

  1. How do the cells walls of fungi differ from the cell walls of plants?

 

Fungal cell walls are composed of chitin while plant cell walls are composed of cellulose.

 

  1. Where in a fungal mycelium would you look to find a diploid nucleus?

 

In a zygote.

 

 

Quiz 7 (Thursday Afternoon)

 

  1. What is the difference between a microsporocyte and a microspore?

 

A microspore results from meiosis of a microsporocyte.

 

  1. Why are all the nuclei of a gametophyte haploid?

 

Because gametophytes develop (mitotically) from haploid spores.

 

  1. Why are all the cells of a sporophyte diploid?

 

Because sporophytes develop (mitotically) from diploid zygotes

 

  1. Are the nuclei of a dikaryotic cell haploid or diploid?  How do you know?

 

Haploid.  Because each mycelium developed from a haploid spore.

 

  1. Define “septate” and “aseptate”.

 

Septate hyphae have cross-walls, aseptate hyphae don’t

 

  1. Why is inappropriate to refer to fungal mating types as sexes?

 

They look alike.  Also, frequently there are more than two.