Practice Exam Crop Improvement

Determining that the plant as whole and not a single flower as the correct unit of selection was not a landmark in plant breeding

False

Selection and Hybridization will continue to be the basic source of high-performing cultivars

true

Methods for breeding Hybrid corn were established around the year 1805

False

Mendel's “laws of inheritance” were adopted immediately upon publishing them.

False

Molecular technologies do not diminish the importance or the need for Selection and Hybridization for crop improvement.

True

Understanding the crop is the last step in any breeder's strategy

False

Breeders limit their search for new genes in the crop's close relatives.

False

A plant breeder must be a specialist in all the disciplines related to his program

False

The use of Molecular genetics techniques created some controversy.

True

As plant breeders depended more and more on science, they became less reliant on skill and chance in establishing new cultivars.

True

Wild plants and domesticated plants have different approaches for resource management.

True

Any region with the greatest genetic variation for a given crop is the probable site of its domestication

True

Hunter-gatherer societies can also be named forager societies.

True

Center of diversity is the geographic area where the plant species exhibits the highest degree of genetic variation

True

Some scientists prefer the term "centers of diversity" instead of exact centers of origin

True

The highest number of cultivated species and wild relatives exist at the center of origin.

False

Plant germplasm may include seeds and pollens but will never include cultured cells.

False

The US is known to have a very satisfactory plant germplasm as it includes all known species.

False

U.S. National Plant Germplasm System includes 2 major divisions only

False

Introductions can be a source of genetic variation in a breeding program

True

New plant introductions may only be used as parents for recrossing.

True

The probability of obtaining superior progeny is very low if the breeder selects superior and suitable parents.

False

Breeding lines can be the parents in crosses.

True

The breeder is limited to the two-parent cross as the only way to create recombination.

False

In a three-way cross, all parents contribute the same percentage of alleles.

False

In a four-parent (double) cross, all parents contribute the same percentage of alleles

True

Three-way and four-way crosses increase the time necessary before selection can start.

True

Mutations utilized as a source of variation are only those that happen naturally.

False

Interspecific crosses are difficult because progeny may be sterile or embryos may not develop.

True

Heritability can be defined as the degree to which variability is transmitted to progeny.

True

A heterozygote genotype will have two identical alleles at a locus.

False

Phenotypes may vary physically and physiologically but never biochemically

False

Backcrosses provide further evidence on breeding behavior of plants.

False

Qualitative traits are expressed in a continuous range of variation (yield).

False

Variation among plants may be due to environment, heredity, and environment × heredity interactions.

True

Two corn plants with the same heredity grown under different fertility levels will differ and this difference will show up in progeny.

False

At least one parent should exhibit characteristics desired in the offspring

True

Some crops can be considered both self- and cross-pollinated.

True

Autogamy is not the same as self-fertilization

False

Slight cross-pollination (~5%) usually occurs in self-pollinated plants.

True

Bermudagrass with chromosome numbers 2n = 18 and 2n = 36 is considered a ploidy series

True

In mitosis, daughter nuclei normally receive exact chromosome copies

True

Double fertilization refers to one sperm fusing with the egg to form a zygote.

False

In corn, pollen grains are produced in little amounts (less than 100 per plant)

False

Monoecious plants have staminate and pistillate flowers on different plants.

False

The pistil consists only of an ovary and stigma

False

Vivipary is extensively used in plant breeding because seeds are not formed.

False

A clone is a group of plants propagated vegetatively from a single plant

True

Self-incompatibility refers to the inability of viable pollen to fertilize flowers of the same or similar genotype.

true

Foreign pollen is unaffected by self-incompatibility and can fertilize the egg.

True

Incompatibility can be caused only by physiological reactions and is not genetically based.

False

Male sterility is caused by non-functional pollen grains.

True

Cytoplasmic male sterility (CMS) is caused by mitochondrial genes interacting with nuclear genes.

True

Genic male sterility (GMS) is caused by mitochondrial genes interacting with nuclear genes.

False