Homework 7: Ch. 28 Protists

Their offspring may be more adaptable to changes in the environment. *Offspring produced by sexual reproduction are genetically different from their parents and may be better able to thrive if the environment changes.*

Syngamy

Gametophyte

Holdfast

Haploid cells are produced by meiosis of diploid cells.

Gametophytes produce cells that undergo mitosis to produce gametes that fuse to form a zygote. *Gametophytes are haploid adults that produce cells that undergo mitosis and form gametes that fuse to form a diploid zygote.*

False * Organisms that exhibit alternation of generations reproduce asexually in the diploid stage by producing haploid cells that form spores, which then germinate into haploid adults. The haploid adults produce haploid gametes that can then participate in sexual reproduction.*

A: amoebas emerge from large capsule B: n C: cells aggregate when food is scarce D: two amoebas fuse to form a zygote E: n F: 2n G: aggregate migrates H: n I: fruiting body releases spores J: n K: one amoeba emerges from each spore L: n *The life cycle of cellular slime molds, such as Dictyostelium, involves haploid cells called amoebas that function independently and move through the use of pseudopodia. In the sexual part of the life cycle, two amoebas may fuse, forming a zygote, which undergoes meiosis. Several rounds of mitosis results in the production of more amoebas. In the asexual part of the life cycle, amoebas gather together when food is scarce, forming a slug-like aggregate. The aggregate migrates, eventually stopping and forming a fruiting body, which releases haploid spores. A single amoeba emerges from each spore.*

Inside an infected mosquito, haploid gametes fuse, forming a diploid zygote that develops into an oocyst. The complete life cycle of Plasmodium requires two hosts. Plasmodium cells infect two specific types of cells in humans. Plasmodium cells are transferred to humans through mosquito saliva. *The figure below shows the two-host life cycle of Plasmodium, the protist that causes malaria. Plasmodium cannot reproduce without infecting both human and mosquito hosts.*

1: a multicellular diploid sporophyte produces haploid spores through meiosis 2: unicellular, haploid spored divide by mitosis to produce haploid gametophytes 3: multicellular, haploid gametophytes produce haploid gametes 4: male and female haploid gametes fuse to produce a diploid zygote 5: the diploid zygote matures into a multicellular, diploid sporophyte *The figure below shows the alternation of generations in Laminaria. A diploid sporophyte produces haploid spores though meiosis. Haploid spores undergo mitosis, producing haploid gametophytes. Male and female gametophytes produce haploid gametes, which fuse to form a diploid zygote. The zygote grows and matures into a diploid sporophyte. *

diplomonads ...parabasalids

alveolata *Dinoflagellates, apicomplexans and ciliates are classified in Alveolata, a group characterized by cells with small membrane-bounded cavities under their cell membranes.*

photosynthetic

kinetoplastids

brown algae, red algae, and green algae

cellular slime molds *Cellular slime molds are amoebozoans*

diatoms

apicomplexan

ciliate *A paramecium makes use of its cilia to move and feed.*

brown algae

ciliates

stramenopila

red algae *The phycobilins and other accessory pigments of red algae allow them to absorb the wavelengths of light that penetrate deep water and to use them in photosynthesis.*

oomycetes

chlorophytes *Chlorophytes (green algae), like green plants, contain both chlorophylls a and b.*