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Biology 112 Lab Practical 1


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Define a population.
a localized group of interbreeding individuals that are able to produce offspring.
What is a gene pool?
all the alleles in the interbreeding population
What is evolution?
a change in the genetic composition of a population due to the frequency of alleles
What is gene mutation?
heritable changes that produce variation in the gene pool
What is natural selection?
the impact of the environment on the survival& reproduction of genotypes within the population is a major force in changing frequency of alleles.
What is gene flow?
the frequency of alleles in the gene pool may change due to the immigration or emigration of organisms
What is genetic drift?
the frequency of alleles in the gene pool may change by pure chance.
What are the three factors that increase genetic variability?
mutations, gene flow, and recombination of alleles
What are the rules for Castle-Hardy Weinberg Law?
1. mutations do not occur, 2. the population size is large, 3.the population is isolated from other populations of the same species, 4. no selection takes place, 5.mating is random
Indicated the allele and genotype frequencies in these populations.
91% tasters and 9%nontasters
allele frequencies: T-.7, t-.3
genotype frequencies: TT-.49 Tt:.42, tt-.09
If the CHW laws are met, what will be the allele frequences in a population of 75% tasters and 25% non tasters after 10 generations.
T:.5 t:.5
Name all the physiological adaptations to living on land that plants have adopted.
a)water transport tissues (xylem) and nutrient transport tissues (phloem)
b)support tissue to resist the pull of gravity, c)waxy cuticle and more ground
What are some differences between monocots and dicots?
a monocot has vascular bundles scattered through the stem.
a monocot has parallel veins in its leaves
study apical meristem
study apical meristem
where is the vascular cambium located?
in between the xylem and ploem, in a dicot
Draw a cross section of a dicot stem.
phloem, pith, vascular cambium, epidermis, xylem
how can you differentiate monocot and dicot roots? give two differences.
dicots have vascular cambium, no pith, and a "cross", structure of xylem in the center. Monocots have xylem and phloem in bundles
does root pressure create an upward or downward movement of xylem sap?
upwards: the higher pressure in the roots and water's cohesive and adhesive properties propel it upwards from roots to stems and leaves.
What is the function of casparian strips (in general)?
casparian strips are located on two out of three walls of endordermal cells, and block the passage of water and minerals from flowering OUT after they pass into xylem cells in the vascular bundle.
What are the four tissues in a plant?
meristematic or growth tissue, vascular tissue, ground tissue, epidermal tissue
What are the three organs in a plant?
roots, stems, leaves
What is collenchyma?
modified types of parenchyma with thickened primary cell walls used for strength and flexibility often found in young stems and petioles; living at maturity
What is parenchyma?
most generalized, undifferentiated type of ground tissue; usually consists of irregularly shaped cells filling spaces between more specialized tissues; photosyn.
What is sclerenchyma?
modified type of parenchyma cell that is dead at maturity; has thickened secondary cell walls impt. for support of the plant; gennerally associated with vascular tissue
What are companion cells?
one of many small cells associated with sieve tubes of the phloem, thought provide the nutrition to the sieve tubes
What are vessel elements?
an elongate xylem cell modified for the transport of water and minerals through the plant; lacks end cell wals;dead at maturity
what is the vascular cambium?
merstematic tissue occuring between xylem and phloem in dicots allowing for secondary growth occur in dicots, these coalesce into a ring of vascular tissue
What is a sieve element?
an elongate phloem cell modified for the transport of organic molecules throught the plant
What is a pericycle?
single layer of cells just outside the vascular tissue and just inside the endodermis in roots; functions as a meristem to start lateral (secondary) root growth
What is the pith/
part of a stem or root made of parenchyma which is internal to the vascular tissue
What is a rhizome?
underground, horizontal stem used for spreading of a plant
What is a tuber?
underground storage organ constructed from a modified stem
What is a stolon?
horizontal above ground stem used to spread a plan; roots at nodes
What are casparian strips?
prevent back flow of water

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