Questions and Answers of Botany An Introduction To Plant Biology

In Question 23, if one chromosome has R and T and the homologous chromosome also has R and T, does linkage matter? What is the single type of genotype that this plant can produce in its
What does the term “multiple alleles” mean? Think about flowers such as roses that have many different colors. Do you think that flower color genes in roses might have multiple alleles? Now think
Figure 16-17 shows a dihybrid cross but it can be analyzed as a monohybrid cross of just smooth seed coat (S) and wrinkled seed coat (s) with complete dominance that should show a 1:2:1 ratio.
Why is it easier to study plastid inheritance than mitochondrial inheritance? What is unusual about both? Do plastids and mitochondria undergo sexual reproduction? Syngamy?
Imagine that you have a plant with no chlorophyll. It is completely white because of a mutation in a plastid gene. Imagine that you cross this plant with an ordinary green plant. In one cross, you
What is a lethal allele? Would you expect most lethal alleles to be recessive (that is, only ll is fatal), or would you expect many of them to be dominant (LL and Ll are both fatal)? Do you think a
If a cell has one set of chromosomes, it is said to be haploid. If it has two sets, it is diploid. What term is used if it has three sets? Multiple sets?
Plants with multiple sets of chromosomes (polyploid plants) have more sets than they need. They are often healthy and vigorous. What might happen to their extra chromosomes and genes over long
Evolution is the gradual conversion of one species into one or several new species. It occurs for the most part by __________________ ________________. Mutations cause new __________________ or new
Relative to a human lifetime, is evolution a process too slow or too fast for us to see it easily?
As the idea of geological evolution developed, it had an impact on biological thinking. Describe the impact. What was the importance of river deltas?
The discovery of evolution by natural selection happened at about the same time as other critical discoveries. Name some of these discoveries. Can you describe how they might have affected biological
Genes and inheritance have an impact on the lives of parents and their progeny, the F1 and F2 generations. Population genetics also deals with genetics, but in a different way. What is the definition
How does an accident differ from natural selection? Would an unusually severe drought with no rainfall at all for 50 years be a selective or a nonselective destructive force?
How does artificial selection differ from natural selection? Do you think the ancestors of lettuce had such soft, nonbitter leaves? Could today’s lettuce plants survive in natural conditions?
Many people assume that natural selection depends on something outside the plant in the environment affecting the plant, but is that true? Wood is always inside the plant. It is never in contact with
One of the conditions necessary before natural selection can occur is that the population must produce more offspring than can possibly grow and survive to maturity in that habitat. Do you think this
Another condition necessary for natural selection to occur is that progeny must differ from each other in their types of alleles. Do you think this is true for most plants or animals? Be careful for
Name several factors that are not part of natural selection.
Change each of the following sentences into ones that are true:(a) Plants produce root hairs in order to absorb more water.(b) Plants close their stomata at night to conserve water.(c) DNA produces
Are plants subjected to just one type of selection at a time or are there multiple selection pressures affecting a plant? The text gives an example of a mutation that improves cold hardiness but that
Why is it that evolutionary changes that result in the loss of a structure or metabolism can come about quickly?
Modern cacti evolved from ancestors that were leafy trees (Figure 17-11), and in the early stages of cactus evolution, leaves were lost; however, the capacity to produce leaves was not lost quickly.
Look at the two cacti in Figure 17-11. Both the leafy Pereskia in part a and the very desert-adapted Gymnocalycium in part b evolved from the same ancestors—leafy trees that were not themselves
What is gene flow? How does it occur?
The Hawaiian Islands were formed as underwater volcanoes that became so tall that they protruded above the ocean’s surface. Being formed from molten rock, they were absolutely sterile at first, but
What is an abiological reproductive barrier? Name several. Is something that is an abiological reproductive barrier for a plant necessarily also one for an animal? Would you guess that small herbs
Differences in flower color, shape, or fragrance are listed as being potential biological reproductive barriers. Do you think they would matter at all in a wind pollinated species? If a plant species
One of the earliest postzygotic barriers to arise is hybrid sterility. Two plants can be crossed, but the resulting seeds grow into sterile plants that cannot reproduce. Is this as important in
What is genetic drift? What is a founder? Are these important in large populations or in small ones? How are these phenomena important when we create national parks and preserves to protect
What is convergent evolution? Euphorbias and cacti are often used as examples of convergent evolution. Have their genotypes converged? Have their phenotypes converged? Both have spines, but if we
What is the theory of chemosynthesis?
Describe the conditions present on Earth at the time of its early second atmosphere. What chemicals and energy sources were present? What chemical in particular was absent? Can you speculate about
Life originated on Earth so long ago that erosion and weathering and metamorphosis of rock have destroyed most traces of the processes that occurred, but oxygen is an interesting exception. What is
Are opening and closing of stomatal pores based on short-distance or long-distance transport? Is osmosis or active transport involved in opening and closing? What ion is especially important?
Water is both cohesive and adhesive. What do these words mean, and how do they affect water’s movement in a plant?
In xylem, the pressure potential is a negative number. Why? What does the weight of the water have to do with this? Stolons, rhizomes, and horizontal vines do not have a problem with the weight of
What is global warming? What is the main gas that causes it? What would happen if the Earth’s atmosphere had a lower concentration of CO2 than it has now? What would happen if it had more?
With oxygen present, not only can NAD+ be regenerated, allowing glycolysis to continue, but even more __________ is formed in the regeneration process.
Two of the following are oxidizing agents and two are reducing agents. Which are which: NAD+, NADP+, NADH, and NADPH?
ATP is an important chemical involved in many of a plant and animal’s metabolic reactions. Yet any plant has only a small amount of it. Can you explain this? When ATP enters a reaction and forces
What is the meaning of the word entropy? Does the entropy of a plant increase or decrease while it is alive? After it is dead?
What is a reduction reaction? Why does a reduction reaction always occur simultaneously with an oxidation reaction?
Name several examples of photoautotrophs and several of heterotrophs. How do photoautotrophs obtain energy? Can a plant be heterotrophic while a seedling and photoautotrophic when older?
Name the three methods of phosphorylation.
In organic molecules, we calculate the oxidation state of carbon by assuming that each oxygen has an oxidation state of _____________________. Each hydrogen has an oxidation state of
In photosynthesis, what is the ultimate source of electrons? What are the benefits of this molecule in terms of its toxicity and the cost of the plant to obtain it?
Describe the absorption spectrum of chlorophyll. Why does it match the action spectrum of photosynthesis?
The most common accessory pigments in land plants are chlorophyll ____________________ and the ____________________. Algae that live in deep water have other accessory pigments because only
Chlorophyll does not use high-energy quanta. Why not? What would happen to the chlorophyll if it did? It also does not use long wavelength radiation either. Why not?
Name the electron carriers that transport electrons from photosystem II to photosystem I. Which ones contain metal atoms, and which do not?
When photosystem I produces NADPH, its reaction center P700 chlorophyll a loses electrons. What would happen if photosystem II did not supply new electrons to P700?
When electrons are removed from water, protons are liberated. Does this occur in the stroma or inside the thylakoid lumen? Can protons move directly across the membrane? Describe the chemiosmotic
Is ADP converted to ATP directly by the reaction center chlorophylls? Do the enzymes that synthesize ATP obtain the necessary energy by interacting directly with the reaction center chlorophylls?
What chemical is the acceptor of carbon dioxide in the C3 cycle? What enzyme catalyzes the reaction, and what is the product?
RuBP carboxylase is by no means an ideal enzyme. Describe some of the problems with its active site and its substrate specificity. If we compare the amino acid sequences of this enzyme from many
Which chemicals are useful for energy storage on a short-term basis? Which are for intermediate term and which are for long term?
What is the “quality” of light? How does it differ for plants in deserts, grasslands, and the canopy of a forest versus for plants in the understory? How does it differ for algae that grow near
How is the quantity of light affected by a plant’s location relative to the equator or the poles? On one side of a mountain or the other? On one side of a valley or the other?
Imagine a leaf in bright light but an atmosphere with no carbon dioxide. Would RuBP carboxylase be functioning? Would the NADP be in the reduced or oxidized form?
Name some of the brightest environments. Describe some protective adaptations that plants may use to shade themselves.
An important factor for plants is the amount of water lost for each molecule of carbon dioxide absorbed. How could the plant be harmed if it loses a lot of water for each carbon dioxide molecule,
In a C4 plant, where is PEP carboxylase located? Where is RuBP carboxylase located?
In a CAM plant, are stomata open during the day or the night? How does this affect the amount of water the plant loses when its stomata are open?
As a CAM plant makes and stores acids during the night, how does this affect the plant’s acidity (its pH)? Think about the acidity of your own blood. Do you think it is allowed to vary by any large
In habitats where water conservation is not especially necessary, is CAM metabolism more or less advantageous than C3 or C4 metabolism? Why?
What is the Kyoto Protocol? How many countries have signed it? Name one country that has not signed it. What are two substances burned in the United States (and all other countries) that produce CO2?
Most plants store excess energy from photosynthesis. Name some times when recovery of stored energy may occur. Does energy recovery always occur in the same sites where photosynthetic capture
When a storage organ becomes active after dormancy and mobilizes its reserves, the starch is usually converted to sucrose for transport. Why is starch not transported?
The oxidation of NADH to NAD+ requires transferring electrons from it onto something else. What are characteristics the ideal recipient would have? What is the recipient actually used? What does it
Under what conditions does plant tissue experience lack of oxygen? How is ATP generated from glucose without oxygen?
Glycolysis can proceed only if ____________ is available. If it cannot be regenerated from NADH, the organism will starve, despite having glucose available.
Imagine that you have two solutions of glucose in water. One solution consists of 1 g of glucose in 100 mL of water. The other consists of 10 g of glucose in 100 mL. Which solution has a more
Unless frozen, water is always in _______________, always ______________ within a plant from areas where it is abundant or under pressure to areas where it is rare or under tension.
The pressure potential of water measures the effect of pressure on water. If a cell had no cell wall, would it have a pressure potential?
What are the three components of water potential? Which of these potentials measures water’s interaction with dissolved material?
Like any other chemical, water has a free energy measured by its water potential. Name three simple ways water potential can be increased.
Would active transport be possible if the molecular pumps were located in a freely permeable membrane?
What is a freely permeable membrane? How does it differ from a completely impermeable membrane or a differentially permeable membrane?
What is the definition of the respiratory quotient (RQ)? The complete aerobic respiration of glucose consumes six molecules of oxygen and produces six of carbon dioxide. What is the RQ for this
The four-carbon sugar erythrose-4-phosphate is the starting material in the synthesis of many compounds. Name two important examples.
The intermediates of all respiratory pathways can be used in _______________ _________________ to make various compounds. It is not ____________________ that they will be completely oxidized to
Some plants generate large amounts of heat. Name two examples. How is the generation of heat beneficial to each of these plants? What is the name of heat-generating respiration?
What is a chemiosmotic potential in mitochondria?
Examine Figure 11-13. Where are the electron carriers of the mitochondrial electron transport chain located—in the matrix, the membrane, or in the crista lumen? As they carry electrons, some of
What are the three basic parts of aerobic respiration? Which steps occur in mitochondria and which in cytosol?
Plants do not make the acid mentioned in Question 11. What do plants make instead during anaerobic respiration? Pyruvate is converted to _________________, and then NADH reacts with that, forming
The reduction of NAD+ to NADH during glycolysis is a problem. Why is this less of a problem if roots absorb nitrates and sulfates or if the plant is synthesizing fatty acids?
During anaerobic respiration in animals, the electron acceptor is pyruvate. What is the acid (or the anion of which acid) that is formed? During hard, fast exercise, your own muscles probably
For the citric acid cycle to occur, pyruvate must be transported from _____________ where glycolysis occurs, across the _____________________ to the ____________________. It is transported as a
The text mentions that the benefit in the citric acid cycle is the generation of more ATP, yet at only one step is ATP produced. How is the citric acid cycle involved in more ATP production than just
Plants have both short-distance and long-distance transport. How long are the distances involved in each?
Plants have several tissues that act as isolation mechanisms. Name two.
Define diffusion. How does this differ from osmosis?
In a beaker of pure water, what is the water potential? Does water potential become more positive or more negative as you add solute to it? Put pressure on it? Add it to dry clay? Add acid to it? In
By adding salt to eggplant, water can be drawn from the tissues. Which has a more negative water potential—eggplant or salt crystals?
In each of the following pairs, circle the one that would probably have the more negative water potential: cell of a wilted leaf—cell of a turgid leaf; guard cells of an opening stoma—regular
Imagine a cell with a water potential of –0.1 MPa being placed in a beaker of solution that also has a water potential of –0.1 MPa. Are the two water potentials in equilibrium? Would any water
Now imagine the same root as in Question 16 being placed in a dry soil in which the little soil water present has a water potential of –1.0 MPa. Would water move from the soil into the root or
Circle the correct word of each pair.a. If a cell [absorbs, loses] water, it will become turgid.b. If a cell [absorbs, loses] water, it will become plasmolyzed.c. If a cell [absorbs, loses] water and

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