High School

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------------------------------------------------ Please help me with some of my Botany questions!

7. If the leptoids of mosses were found to contain a protein whose gene had the same nucleotide sequence as the gene that codes for P-protein, would that be significant evidence for either the homology or analogy of leptoids and phloem?

8. You will see sporophytes only if you examine mosses closely. They look like green or brown "__________" standing up on the green gametophyte, but sporophytes are (circle one: present almost all the time, only present at certain times of the year).

9. Do mosses have an alternation of isomorphic or heteromorphic generations? That is, can you easily tell a moss gametophyte from a moss sporophyte? When we look at leafy green moss plants, what are we seeing—the gametophyte or the sporophyte? In a flowering plant species, would the equivalent stage be the plant or the pollen grains and megagametophytes?

10. The leafy, green moss plants that are so familiar are gametophytes, haploid plants. This is very different from flowering plants and other seed plants. Does the leafy green moss plant grow from a spore or from a fertilized egg? Does the moss plant have both a paternal parent and a maternal parent?

11. Draw a single moss plant, similar to the one in Figure 20-10. Be certain to show the gametophyte and the sporophyte. Now draw one without the sporophyte, showing only the gametophyte. The sporophytes usually have only a very brief life, and after they shed their spores, the gametophytes let them die.

12. Draw and label the life cycle of a moss, being certain to show gametangia and sporangia. Which parts are haploid and which are diploid? Where and when does meiosis occur? Plasmogamy? Karyogamy?

13. In the majority of mosses, which lack hydroids and leptoids, water is conducted along the __________ of the plant by __________ action.

14. The leafy, green moss plants being gametophytes have gametangia, structures that produce gametes. What is the name of the gametangium that produces sperm cells? The gametangium that produces egg cells? Can one single moss gametophyte bear both of these? Do some species have plants that produce only egg cells?

15. The sporophyte of a moss usually has a stalk called a __________ and a simple apical sporangium called a __________.

16. Many people often think of mosses as plants adapted to rainy areas, areas that are usually wet. Are any mosses adapted to deserts? Can some mosses lose much of their water—similar to how a seed does before being planted—and still survive?

Answer :

Final answer:

If the nucleotide sequence of the gene in moss leptoids matches that of the P-protein gene, it provides significant evidence for the homology of leptoids and phloem. Mosses have an alternation of generations, with the leafy green moss plant being the gametophyte and the sporophyte being a brief stage in their lifecycle. The moss plant grows from a spore and only has a maternal parent.

Explanation:

If the leptoids of mosses were found to contain a protein whose gene had the same nucleotide sequence as the gene that codes for P-protein, it would be significant evidence for the homology of leptoids and phloem. Homology refers to the similarity between structures or genes in different organisms due to their common ancestry. The presence of the same gene sequence suggests that leptoids and phloem have a shared evolutionary history.

Mosses have an alternation of generations where both the gametophyte and the sporophyte stages are present. The gametophyte is the leafy, green moss plant that we see, while the sporophyte is the tiny stalk-like structure that grows on the gametophyte. In a flowering plant, the equivalent stage would be the plant itself, not the pollen grains and megagametophytes.

The leafy, green moss plant grows from a spore, not from a fertilized egg. It only has a maternal parent and does not have a paternal parent.