28. Plants

Which example below is a clade of nonvascular plants?

When you see a green, "leafy" moss, you are looking at the __________.

Rhizoids __________.

Which of the following produces eggs and sperm?

The gametophyte generation of a moss __________.

Fertilization in moss occurs when sperm swim from a(n) __________ and down the neck of a(n) __________.

How are gametes produced by bryophytes?

In mosses, haploid __________ directly produce buds that grow into gametophores.

Which structure of a bryophyte sporophyte is specialized for gradual spore discharge?

In which bryophyte structure specifically does a zygote develop into an embryo?

Sphagnum is a __________ that forms extensive deposits of partially decayed organic material.

The gametophyte stage of the plant life cycle is most conspicuous in __________.

What does it mean to say that a signal is transduced? a. The signaling molecule enters the cell directly and elicits a cellular response. b. The signal is generated by the production of proteins. c. The physical form of the signal changes between the outside of the cell and the inside. d. The signal is amplified.

Suppose an efficient conducting system evolved in a moss that could transport water and other materials as high as a tall tree. Which of the following statements about 'trees' of such a species would not be true? a. Spore dispersal distances would probably increase. b. Females could produce only one archegonium. c. Unless its body parts were strengthened, such a 'tree' would probably flop over. d. Individuals would probably compete more effectively for access to light.

Summarize the experimental evidence in sponges showing that animal cells adhere to each other selectively. Explain the molecular basis of selective adhesion.

What is the significance of the observation that many signal transduction pathways create a network, where they intersect or overlap?

Steroid hormones, like most lipid-soluble signaling molecules, are processed directly. How does the absence of a signal transduction cascade in the processing of steroid hormones affect (a) signal amplification?

Suppose you have an antibody that binds to the receptor tyrosine kinase illustrated in Figure 11.16. When you add this antibody to the cell, you find that it activates the cell response, even when no signaling molecule is present. Explain this result.

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. Researchers hypothesized that small animals called springtails (a type of arthropod) facilitate sperm transfer in mosses. To test this hypothesis, the researchers grew patches of male and female mosses at varying distances from each other and in the presence or absence of springtails. They later checked to see how many sporophytes were found in each female patch (as an indicator that fertilization had occurred). Their results are shown in the graph here (** means P<0.01, * means P>0.05. What conclusions can be drawn about the role of the springtails during the reproductive cycle of the mosses?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. What structure do moss sperm use for motility, and how does that reflect the evolution of land plants from green algae?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. Beyond the results presented here, what other evidence would be useful when drawing conclusions about the role of springtails in moss reproduction?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. A friend in your biology study group claims that eggs in mosses are fertilized by spores. What is wrong with that statement?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. A friend in your biology study group claims that eggs in mosses are fertilized by spores. What is wrong with that statement?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. Besides springtails, are there other ways moss sperm may be transferred from male to female gametophytes?

Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. Animals are responsible for pollinating many flowering plants. Did animal-mediated fertilization originate with flowering plants, or was this mode of sperm dispersal likely in place before the origin of flowering plants? Explain.