Exam 31: Plant Structure, Growth, and Reproduction

Plants differ from many animals because they undergo indeterminate (continual) growth. Indeterminate growth is common in clonal plants because a single clone can continually produce new clones without undergoing sexual reproduction, even if the plant is capable of doing so. Senescence, an inability to undergo cell division as an organism ages, also occurs in many plants and animals. However, scientists have had a difficult time establishing the occurrence of senescence in cloning plants because of their indeterminate growth patterns. Mutations in somatic cells are common during asexual growth, and these mutations lead to a decrease in sexual fitness. Scientists hypothesize that over time, as these mutations accumulate, they may contribute to senescence in clonal plants. To test this theory, scientists studied a naturally growing population of trembling aspen (Populus tremuloides), a tree species that grows clones from its root system but is capable of sexual reproduction. To determine if trembling aspens senesce, they compared genetic data of estimated tree age with the variable of "diminishing fertility": the amount of pollen released by male aspen trees. Here are the results for this part of the study: Source: Adapted from Ally, D., Ritland, K., & Otto, S. P. (2010). Aging in a long-lived clonal tree. PLoS Biol, 8(8): e1000454. doi:10.1371/journal.pbio.1000454. -If a male trembling aspen clone loses its ability to produce pollen, how is its reproduction capability affected?

What event that occurred around 10,000 years ago led to genetic changes in wheat?

What happens to the cotyledons of pea and maize (corn) seeds?

How many chromosomes are there in an unfertilized maize (corn) egg cell nucleus as compared to a maize (corn) pollen cell nucleus?

Which statement is false?

Plants differ from many animals because they undergo indeterminate (continual) growth. Indeterminate growth is common in clonal plants because a single clone can continually produce new clones without undergoing sexual reproduction, even if the plant is capable of doing so. Senescence, an inability to undergo cell division as an organism ages, also occurs in many plants and animals. However, scientists have had a difficult time establishing the occurrence of senescence in cloning plants because of their indeterminate growth patterns. Mutations in somatic cells are common during asexual growth, and these mutations lead to a decrease in sexual fitness. Scientists hypothesize that over time, as these mutations accumulate, they may contribute to senescence in clonal plants. To test this theory, scientists studied a naturally growing population of trembling aspen (Populus tremuloides), a tree species that grows clones from its root system but is capable of sexual reproduction. To determine if trembling aspens senesce, they compared genetic data of estimated tree age with the variable of "diminishing fertility": the amount of pollen released by male aspen trees. Here are the results for this part of the study: Source: Adapted from Ally, D., Ritland, K., & Otto, S. P. (2010). Aging in a long-lived clonal tree. PLoS Biol, 8(8): e1000454. doi:10.1371/journal.pbio.1000454. -If you generalize the trends in data to 20,000 years, what can you conclude?

Which part of this root tip is the vascular cylinder?

The part of corn that is used for fuel or food for humans is the

Angiosperms consist of the clades

What helps regulate the movement of carbon dioxide into and out of a leaf?

A seed develops from a(n)

Which substance, by providing strength, allows sclerenchyma cells to provide support and play a role analogous to that of an animal's skeleton?

Aspen trees are the most widely distributed tree in North America. A forest of many aspen trees, some of which may be tens of thousands of years old, is actually one single clone. What is likely to be the greatest threat to the long-term survival of aspen forests?

If you carve your initials in the trunk of a tree, will they move up as the tree grows?

The redwood groves in Northern California are one of America's greatest natural resources. Redwoods can live more than 2,000 years and grow taller than 350 feet. When tourism became popular in the late 1800s, large tunnels were cut through the center of several of these giant trees to allow wagons to pass through (and to attract tourists to the location). Even today, visitors wait in line to be photographed driving their cars through a tunnel. When the groves were converted into national parks, the tunneling was discontinued, but several tunneled trees are still alive. -When the redwood tunnels were first constructed, not much consideration was given to the long-term effects of a tunnel on a tree's health. Nevertheless, many trees have survived more than 100 years after a tunnel was cut through their trunks. This is possible because

A 20-foot-tall tree that seemed to have stopped growing was cut down by the forester who was concerned that it might be diseased. She had planted it 43 years earlier. Measurements over the past 10 years had shown that the tree's height varied only 2 or 3 inches each year, some years with a height increase and some years with a height decrease. Other data indicated that the tree had 41 rings of similar width and had produced similar numbers of nuts every year for the last 30 years. Based on these data, which conclusion was most likely a part of the forester's report on the tree's health?

The male organ of a flower is the

-Which structure can change to regulate the amount of CO2 entering the leaf?

The growth that pushes a root down through the soil takes place through

While cleaning out the attic, you find a packet of seeds that your grandmother gathered from her garden. You plant them outside, and some of them sprout. What was the condition of these germinating seeds while they were in the attic?