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PLS 002 MT 1
Flashcards to help study for Midterm 1 in PLS 002.
| Question | Answer |
|---|---|
| What is the second law of thermodynamics? | Every energy transfer or transformation increases the entropy of the universe. |
| What does entropy mean? | The possible different configurations of a specific setup of atoms. |
| Why, contrary to popular perception, does the 2nd law of thermodynamics not contradict the occurrence of life and its evolution towards increasing complexity over time? | The entropy of a closed system increases. |
| What is a leaf? | A flat, often green part of a plant that's individually attached to the stem of a plant. Consists of a bud. |
| What is a leaflet? | Attached to a common stalk or rachis. Small in size and doesn't consist of a bud. |
| What is a meristem? | A region of unspecialized cells in a plant capable of cell division. |
| Which characteristics to all leaves share? | They all have chlorophyl, lignin, and an axillary bud. |
| Do grasses produce secondary xylem? Why or why not? | No, because they are monocots, which are not capable of producing secondary xylem. |
| Why can most animal cells not sustain high pressure inside the cell, but plant cells can? | Their cells have a rigid cell wall around the plasma membrane, unlike animal cells. |
| What is the connection between vascular tissue and fascism? | Vascular tissue is bundled into fascicles (which contain a fascicular cambium) which has the same word root as fascism. |
| What are charophytes, and what is their relation to land plants? | They are green algae. They are the closest living relatives to land plants. They are the ancestral lineage that gave rise to land plants. |
| What are the two generations of land plants? | Nonvascular (gametophyte-dominant) and vascular (sporophyte-dominant) |
| What generation of land plants produces spores? | Vascular |
| What generation of land plants produces gametes? | Non-vascular |
| In land plants, which type of cell division creates spores? | Meiosis |
| In land plants, which type of cell division creates gametes? | Mitosis |
| In the 50 million years or so after land plants first appeared, the average surface temperature on Earth dropped steeply. Why can this be partly attributed to plants? | The plants took in the carbon dioxide from the atmosphere. |
| Extant of nonvascular plants | Somewhat diverse |
| Extant of seedless vascular plants | Not too diverse |
| Extant of non-flowering seed plants (gymnosperms) | Least diverse |
| Extant of flowering plants (angiosperms) | Most diverse |
| Which group of land plants includes the longest-lived, tallest, and most massive single organisms known? | Conifers |
| Which group of land plants disperse via spores? | nonvascular plants (or bryophytes) such as mosses , and seedless vascular plants such as ferns |
| Which groups of land plants disperse via seeds? | vascular plants containing seeds (such as gymnosperms and angiosperms) |
| Are dicots (dicotyledonous plants – angiosperms with two "seed leaves" [cotyledons]) a monophyletic group? | No |
| Are monocots a monophyletic group? | Yes |
| What is the name for the cells that are the products of meiosis in land plants? | Haploids |
| How do ferns disperse their offspring? | Through spores |
| What is the dominant sub-group of Gymnosperms? | Conifers |
| What is the most economically important group of land plants? | Monocots |
| Why might a farmer prefer to use seeds rather than clonal propagation to produce lots of plants? | It's less time-intensive and they want genetic variation. |
| Why might a farmer prefer to use clonal propagation rather than seeds to produce lots of plants? | They want a large amount of plants with a specific trait. |
| What is the purpose of auxin (indole-3-acetic acid, IAA) in propagation using cuttings? | It promotes the production of adventitious roots |
| From which area of a plant – more distal (farther from the base) or more basal (closer to the base) – would you take a cutting if your objective were to graft it onto an almond rootstock? Why? | More distal, because you want to make flowers during this process, and flowering happens away from the base. |
| From which area of a plant – more distal (farther from the base) or more basal (closer to the base) – would you take a cutting if your objective were to create a whole new plant? Why? | More basal, because the juvenile tissue closer to the base is the most likely to root. |
| Name a reason why a farmer or grower would use grafting (regarding flowering). | It reduces the time to get flower production. |
| Name a reason why a farmer or grower would use grafting (regarding plant wounds). | It heals a wounded part of a plant. |
| What is it called when a plant produces seeds without fertilization? | It's called agamospermy or apomixis. |
| What is meant by a "whorl" of leaves? | All leaves are attached to a node. |
| Name the four whorls of modified leaves in flowers. | The gynoecium, androecium, corolla, and calyx. |
| Respective parts of the gynoecium | Pistils |
| Respective parts of the androecium | Stamens |
| Respective parts of the corolla | Petals |
| Respective parts of the calyx | Sepals |
| A flower has stamens and pistils. Is this flower from a dioecious or monoecious species? | Monoecious |
| Monoecious means | Both male and female flowers are on the same plant. |
| Dioecious means | Male and female flowers are on separate plants. |
| "Perfect" flowers mean | Individual flowers have both male and female parts. |
| How many nuclei does a mature microgametophyte contain, in a typical flowering plant? | Three |
| Why does the endosperm in a seed of a flowering plant typically contain more than two copies of the genome? | The fusion of one sperm cell with two central-cell (polar) nuclei during double fertilization creates a triploid (or greater) endosperm, which has three sets of chromosomes. |
| A colorful, fleshy structure contains a seed. Is the structure necessarily a fruit, and why? | No, because the structure has to have been derived from the ovary of a flower, which was not assumed here. |
| Why are fully mature seeds lighter than less-mature seeds of the same species? | This is because seeds dehydrate before they reach maturity. |
| How many nuclei does a mature megagametophyte contain, in a typical flowering plant? | Eight |
| Are seeds more likely to germinate under high temperatures, or under low temperatures? | They are more likely to germinate under whatever temperatures they happen to evolve for. |
| Suppose you cross two plants that are both heterozygous for a given trait. On average, what fraction of their offspring will be heterozygous for the trait? | Half of their offspring will be heterozygous for the trait. |
| Which type of plant will generally have more homozygous loci: a plant with a primarily selfing habit, or a plant with a primarily outcrossing habit? | A plant with a primary selfing habit. |
| Why do inbred populations often have reduced vigor or productivity? | This is because inbreeding depression occurs, which occurs due to the increased homozygosity of recessive (deleterious) alleles. |
| Which of these modern breeding techniques is better suited for a trait that is controlled by many distinct genetic loci: marker-assisted selection or genomic selection? | Genomic selection because marker-assisted selection is used based on a single genetic locus. |
| There are two different ways that sexual reproduction creates new combinations of alleles. One way is the fusion of gametes from different parents. What is the other way? | Crossing over and independent assortment is the other way, which shuffles alleles within each parent's chromosomes. |
| What is backcrossing, and why is it necessary in traditional plant breeding? | Backcrossing introduces a desirable trait from a donor line to a recipient line. |
| What is biolistic transformation? | The physically-mediated method of introducing DNA fragment(s) into a plant genome. |
| What is Bt corn, and when was it introduced into the US market? | This is a type of corn with the Bt gene, which produces a protein that kills European corn borer larvae. It was introduced into the US market in 1996. |
| True or False: Very little acreage in the US is actually planted with genetically engineered crops. | False, because more than ninety percent of corn, soybean, and cotton grown in the US is genetically-modified. |
| What barriers, apart from the difficulty of gene-editing itself, are faced by plant biotechnologists who wish to bring genome-edited plants to market? | Genetically-modified plants are expensive to commercialize, are not widely-accepted by consumers, and there are regulations regarding genetically-modified plants such as approval requirements, and mandatory labeling standards for foods that use them. |
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