Horticulture Science - Plant Improvement

What is one of the primary objectives when identifying plants for the development of agriculture? a) Their ability to survive in harsh natural environments b) Their potential for rapid genetic mutation c) Their reliability for cultivation, harvesting, and storage d) Their unique aesthetic qualities

c) Their reliability for cultivation, harvesting, and storage. The early stages of agriculture really hinged on finding plants that could consistently provide food and be easily managed, which meant they needed to be reliable from seed to storage.

Approximately how many years ago did organized agriculture begin, leading to continuous improvement in crop productivity and quality? a) 2,000 years ago b) 6,000 years ago c) 10,000 years ago d) 20,000 years ago

c) 10,000 years ago. It’s quite a long history, isn't it? This marks the beginning of a deliberate effort to enhance plants for human benefit.

A cave painting from North Africa depicting women harvesting grain dates back approximately how many years? a) 1,000 years b) 3,000 years c) 6,000 years d) 10,000 years

c) 6,000 years. This specific detail highlights the ancient roots of agricultural practices, showing how long people have been interacting with plants in this way.

Which of the following traits is NOT specifically mentioned as a target for improvement in horticultural crops, separate from agronomic crops? a) Taste b) Color c) Drought tolerance d) Size and shape

c) Drought tolerance. While drought tolerance is improved in general crops, the question asks for traits specifically mentioned for horticultural crops beyond general improvements. Taste, color, size, and shape are quality traits highlighted as important for horticultural crops, whereas drought tolerance is listed as a general improvement for all plants.

What characteristic of tomato plants has been modified for mechanical harvesting? a) Increased resistance to environmental stress b) Uniform ripening c) Enhanced flavor profile d) Reduced seed count

b) Uniform ripening. To make mechanical harvesting efficient, tomatoes need to ripen at the same time, which is a key adaptation for modern agricultural practices.

Beyond uniform ripening, what other physical trait of tomatoes has been altered to suit mechanical harvesting? a) Softer skin b) Smaller size c) Thicker skin d) More elongated shape

c) Thicker skin. This helps the tomatoes withstand the rigors of mechanical harvesting without bruising, protecting the quality of the fruit.

Which of the following is a key reason why agricultural plant selection differs significantly from natural selection? a) Agricultural selection always leads to increased genetic diversity. b) Natural selection focuses on traits beneficial to humans. c) Agricultural selection is based on the utility of plants to the grower. d) Natural selection aims to create sterile varieties.

c) Agricultural selection is based on the utility of plants to the grower. This is a crucial distinction! Natural selection favors traits for survival in the wild, while agricultural selection prioritizes traits that serve human purposes, like yield or ease of harvest.

Charles Darwin proposed what as the driving force for evolution? a) Genetic engineering b) Natural selection c) Polyploidy d) Deliberate hybridization

b) Natural selection. This is a foundational concept in biology, emphasizing "survival of the fittest" in a natural environment.

True or False: Plants selected for agricultural purposes would generally be successful under conditions of natural selection.

False. This is a common misconception! Many agriculturally selected traits, like seeds that don't disperse easily or sterile showy flowers, are actually detrimental in a natural environment where plants need to reproduce and spread on their own.

What is considered the "raw ingredient" for plant improvement? a) Uniformity between individuals b) Variation between individuals c) Stable genetic code d) Absence of environmental factors

b) Variation between individuals. If all individuals were identical, there would be no basis for selecting superior traits, right? Variation provides the possibilities for improvement.

If genetically identical plants are grown in different environments, and they grow differently, what is the cause of this variation? a) Genetic variation b) Allelic variation c) Environmental variation d) Phenotypic mutation

c) Environmental variation. This highlights how external conditions can influence the expression of traits even when the underlying genetic code is the same. It’s why scientists try to control environmental factors in experiments!

Variation in yield or quality between different fields or production areas is primarily accounted for by which type of variation? a) Genetic variation b) Inherited variation c) Environmental variation d) Chromosomal variation

c) Environmental variation. Think about it: the soil, water, and climate differ across fields, leading to differences in how plants perform even if they're the same variety.

If plants differ when they are grown under uniform conditions, what is the likely cause of their differences? a) Environmental variation b) Climatic variation c) Genetic variation d) Pathogen-induced variation

c) Genetic variation. When the environment is kept constant, any observed differences must stem from variations in their genetic makeup. This is a key way to identify truly distinct genetic lines.

What is the fundamental unit of inheritance? a) Chromosome b) Nucleus c) Protein d) Gene

d) Gene. Genes carry the instructions for an organism's traits, passed down from one generation to the next.

What are genes encoded by? a) Proteins b) RNA sequences c) The sequence of bases (A, C, G, T) in DNA d) Chromosomes

c) The sequence of bases (A, C, G, T) in DNA. This sequence is like the alphabet of life, spelling out the instructions for building and operating an organism.

Where are chromosomes primarily contained within a plant cell? a) Cytoplasm b) Mitochondria c) Nucleus d) Cell wall

c) Nucleus. The nucleus is the control center of the cell, housing the genetic material organized into chromosomes.

What is the primary function of most genes? a) To regulate environmental responses directly b) To encode proteins c) To store energy d) To provide structural support to the cell

b) To encode proteins. Proteins are the workhorses of the cell, carrying out almost all essential functions, so genes are essentially blueprints for these crucial molecules.

The process of converting information from DNA to RNA, and then from RNA to protein, is fundamental. What does the 'protein' step primarily involve? a) DNA replication b) Genetic mutation c) Carrying out essential functions d) Packaging DNA into chromosomes

c) Carrying out essential functions. Proteins are responsible for the vast majority of cellular processes, from enzymatic reactions to structural support.

Approximately how many genes are estimated to be in plants? a) 5,000 to 10,000 b) 10,000 to 20,000 c) 20,000 to 30,000 d) 30,000 to 40,000

c) 20,000 to 30,000. It's quite a lot, isn't it? This shows the complexity of even a seemingly simple plant.

What is the source of genetic variation between individuals? a) Differences in the environmental conditions they are grown in. b) Differences in the sequence of bases (A, C, G, T) in genes. c) Differences in their protein structures. d) Differences in their overall chromosome number.

b) Differences in the sequence of bases (A, C, G, T) in genes. Even a tiny change in this sequence can lead to a different form of a gene, which we call an allele.

What are different forms of the same gene called? a) Genotypes b) Phenotypes c) Alleles d) Mutations

c) Alleles. These variations in genes contribute to the diversity we see in traits.

Alleles: Different forms of the same gene are called alleles. Genes are termed alleles if they occupy the same position on homologous chromosomes and affect the same trait

Genotypes: The genetic information carried by an individual plant is referred to as its genotype.

Phenotypes: The appearance and performance of a plant are referred to as its phenotype. A plant's phenotype is determined by both its genotype and the environment in which it is grown

Mutations: Errors can occur constantly as plants grow and cells divide, leading to mutations that may result in changes in plant characteristics. While a majority of mutations are deleterious, some are not and can aid in developing new cultivars.

True or False: All alleles have drastic, negative effects on an organism.

False. While some alleles can cause serious conditions like cystic fibrosis in humans, most allelic variants do not have such severe consequences. Many just lead to differences in traits like flower color or height.

What term refers to the genetic information carried by an individual plant? a) Phenotype b) Genome c) Genotype d) Trait

c) Genotype. This is the complete set of genes an organism possesses.

What term refers to the appearance and performance of a plant? a) Genotype b) Allele c) Phenotype d) Inherited trait

c) Phenotype. This is what you actually observe, and it's a result of both the plant's genes and its environment.

Phenotype is determined by which two factors? a) Genetic variation and allelic expression b) Genotype and environmental conditions c) Chromosome number and protein synthesis d) Natural selection and artificial selection

b) Genotype and environmental conditions. This interaction is fundamental to how an organism looks and performs. It's why two plants with the same genes might look different if grown in different places.

Traits controlled by only one or two genes, allowing plants to be placed into distinct categories, are called: a) Quantitative traits b) Polygenic traits c) Simply inherited traits d) Continuous traits

c) Simply inherited traits. These are often easier to track and predict in breeding because their expression is quite straightforward, like Mendel's work with flower color.

Gregor Mendel famously used which type of trait in his foundational genetics experiments? a) Yield b) Drought tolerance c) Flower color d) Flavor

c) Flower color. This is a classic example of a simply inherited (qualitative) trait, perfect for demonstrating basic inheritance patterns.

What term describes traits that are affected by the actions of many genes, resulting in continuous variation within a population? a) Qualitative traits b) Simply inherited traits c) Mendelian traits d) Quantitative traits

d) Quantitative traits. These are much more complex and often show a spectrum of variation, like height or weight, because so many genes contribute.

Which of the following is NOT explicitly mentioned as an example of a quantitative trait important for plant production? a) Yield b) Flower color c) Flavor d) Drought tolerance

b) Flower color. Flower color is given as an example of a simply inherited (qualitative) trait, not a quantitative one. Yield, flavor, and drought tolerance are explicitly listed as quantitative.

Which strategy for plant improvement was used by early agriculturists and is still common for woody ornamental plants due to their long generation times? a) Deliberate hybridization b) Development of F1 hybrids c) Identification of desirable varieties in natural populations d) Creation of polyploids

c) Identification of desirable varieties in natural populations. This is the most basic form of selection, simply finding and using what already exists that fits a need.

What are "sports" in the context of plant improvement? a) Plants developed through intentional crosses for specific athletic events. b) Result of rare spontaneous mutations in cultivated plants with desirable characteristics. c) Plants exhibiting hybrid vigor from crossing two inbred lines. d) Varieties resistant to environmental stresses, found in extreme conditions.

b) Result of rare spontaneous mutations in cultivated plants with desirable characteristics. Sports are exciting because they offer a new, unexpected variation that can be very valuable.

Which of the following is an example of a 'sport'? a) A newly bred disease-resistant wheat variety. b) A seedless Navel orange. c) A hybrid corn plant with increased yield. d) A triploid watermelon.

b) A seedless Navel orange. This is a classic example of a sport, originating from a single branch mutation on an orange tree.

What is a chimera in plant improvement? a) A plant that spontaneously reverted to its wild type. b) A plant where only one layer of tissue is altered by a mutation. c) A hybrid resulting from a cross between two different genera. d) A plant grown from a seed that has been genetically modified.

b) A plant where only one layer of tissue is altered by a mutation. This is a fascinating type of sport where the genetic change is localized, leading to distinct patterns like variegation.

In thornless blackberries, which layer of tissue is altered in a chimera? a) Mesophyll layer b) Vascular tissue c) Epidermal layer d) Cortex layer

c) Epidermal layer. The outermost layer is where the mutation occurs, preventing thorn production.

For a thornless blackberry sport, if stems are produced by propagation from tissues other than the altered epidermal layer, what characteristic would they likely exhibit? a) They would remain thornless. b) They would produce thorns. c) They would become sterile. d) They would develop variegated leaves.

b) They would produce thorns. This is a key point about chimeras – the trait is stable only if propagated from the altered tissue layer. If you use underlying tissue, you lose the "sport" characteristic.

The red flecks on a White Sim' carnation, which is a sport of 'Red Sim', indicate what about the underlying mesophyll tissue? a) It is sterile. b) It is unable to produce red pigments. c) It is able to produce red pigments. d) It is resistant to disease.

c) It is able to produce red pigments. This shows that the mutation is in the epidermal layer, not the underlying tissue, which retains its original ability to produce pigment.

Many cultivars with variegated leaf color are examples of what type of plant improvement that were first identified as sports? a) Polyploids b) Hybrids c) Chimeras d) Transgenic plants

c) Chimeras. The varied color patterns in leaves are often due to a mutation in one cell layer, which then expresses differently than the others.

What is polyploidy in plants? a) An organism with a single set of chromosomes (n). b) An organism with more than the normal diploid (2n) number of chromosomes. c) An organism that has lost one or more chromosomes. d) An organism that has gained a single extra chromosome.

b) An organism with more than the normal diploid (2n) number of chromosomes. This often leads to larger cells and, consequently, larger plant parts.

What is a common beneficial effect of polyploidy in plants? a) Smaller fruit b) Increased disease susceptibility c) Larger cells, resulting in larger fruit d) Reduced generation time

c) Larger cells, resulting in larger fruit. This is a very desirable trait for many horticultural crops, leading to bigger yields.

Which of the following fruits is mentioned as an octoploid (8n)? a) Tart cherries b) Winesap apples c) Strawberries d) Watermelons

c) Strawberries. Their octoploid nature contributes to their often large fruit size.

What is the ploidy level of Winesap apples? a) Diploid (2n) b) Triploid (3n) c) Tetraploid (4n) d) Octoploid (8n)

b) Triploid (3n). This specific detail shows how different ploidy levels are present across various crops.

What is a key characteristic of "seedless" watermelons? a) They are diploid. b) They produce viable seeds that are simply very small. c) They are triploid, causing seeds to remain immature and soft. d) They are a result of genetic engineering to remove seed development genes.

c) They are triploid, causing seeds to remain immature and soft. The odd number of chromosome sets (3n) disrupts proper seed development.

How are "seedless" watermelons typically produced? a) By crossing two diploid (2n) plants. b) By crossing a diploid (2n) plant with a tetraploid (4n) plant. c) By crossing two tetraploid (4n) plants. d) Through spontaneous mutation in a wild watermelon.

b) By crossing a diploid (2n) plant with a tetraploid (4n) plant. This specific cross results in the desired triploid offspring that produce seedless fruit.

Which of these plants is listed as an example where polyploidy leads to larger flowers? a) Tomato b) Corn c) Marigold d) Apple

c) Marigold. Polyploidy can enhance ornamental traits like flower size, making them more appealing.

What observation-based plant improvement strategy laid the groundwork for modern plant breeding? a) Genetic modification using recombinant DNA technology. b) Selection of varieties, sports, and polyploids from natural variation. c) Marker-assisted selection for specific genes. d) Induced mutagenesis.

b) Selection of varieties, sports, and polyploids from natural variation. Before we understood genetics deeply, keen observation was the primary tool for improving crops.

Modern crop improvement heavily relies on plant breeding with the development of what understanding? a) Soil chemistry b) Weather patterns c) How traits are inherited d) Global trade routes

c) How traits are inherited. Understanding genetics revolutionized plant breeding, making it a much more directed and scientific process.

What is the core definition of plant breeding as a deliberate process? a) Random collection of diverse plant species. b) Deliberate hybridization of plants with complementary traits and selection of elite lines. c) Propagation of plants solely through asexual means. d) Cultivation of plants only in their natural environments.

b) Deliberate hybridization of plants with complementary traits and selection of elite lines. This is the essence of modern plant breeding—combining desirable traits to create something even better.

What is the first fundamental step in plant breeding? a) Cross the two plants. b) Evaluate performance of progeny. c) Identify plants with complementary characteristics that can hybridize. d) Collect seed and grow up progeny.

c) Identify plants with complementary characteristics that can hybridize. You can't start crossing until you know what you want to cross and why! This is the planning stage.

If you want to combine uniform ripening from Parent A (tomato) with resistance to TMV from Parent B (tomato), what complementary characteristic would you be looking for in Parent B for the TMV resistance? a) Low soluble solids b) High yield c) Resistant to TMV d) Continuous ripening

c) Resistant to TMV. This is the specific trait from Parent B that complements the desired uniform ripening from Parent A.

During the crossing of two plants in a breeding program, what is the term for removing the male reproductive parts of the female parent flower? a) Pollination b) Fertilization c) Emasculation d) Germination

c) Emasculation. This ensures that the female parent is pollinated by the desired male parent, preventing self-pollination.

After crossing plants and collecting seeds, what is the next step in the plant breeding process? a) File for a patent. b) Propagate the improved variety. c) Evaluate performance of the progeny in subsequent generations. d) Select the best progeny.

c) Evaluate performance of the progeny in subsequent generations. You need to see how the offspring perform to know if the cross was successful.

1. Identify plants with complementary characteristics that can hybridize. For example, when breeding tomatoes, a breeder might be interested in combining traits like uniform ripening, low soluble solids, and susceptibility to Tobacco Mosaic Virus (TMV) from "Parent A" with continuous ripening, high soluble solids, resistance to TMV, and low yield from "Parent B".

2. Cross these two plants - This involves emasculating the female parent, collecting pollen from the male parent, and then pollinating the female parent by hand.

3. Collect seed and grow up progeny.

4. Evaluate performance of the progeny in subsequent generations. The decision on which generation to evaluate depends on the specific breeding scheme being used. This evaluation is carried out over several years and at many sites to ensure that the selected varieties perform reliably

5. Select the best progeny after evaluating their performance

6. Propagate the improved variety. This can involve either the production of seed or through asexual propagation.

7. File for a "Plant Variety Patent" or a normal utility patent to protect the invention.

The decision on which generation to evaluate in a plant breeding scheme primarily depends on what? a) The available funding b) The specific breeding scheme being used c) The number of genes involved d) The type of pollinator available

b) The specific breeding scheme being used. Different breeding methods have different timelines for when the most effective evaluation can occur.

How is the selection of the best progeny carried out to show that selected varieties perform reliably? a) By evaluating them only once in a controlled greenhouse setting. b) By evaluating them over several years and at many sites. c) By testing them against only one known disease. d) By relying solely on genetic markers.

b) By evaluating them over several years and at many sites. This rigorous testing ensures that the new variety is truly robust and performs well under various real-world conditions.

What is the final fundamental step listed in the plant breeding process after propagation of the improved variety? a) Genetic sequencing b) Releasing the variety to the public for free c) Filing for a "Plant Variety Patent" or a normal utility patent d) Mass production of seeds for global distribution

c) Filing for a "Plant Variety Patent" or a normal utility patent. This is crucial for protecting the breeder's investment and invention, allowing them to benefit from their hard work.

1. Identify plants with complementary characteristics that can hybridize. For example, when breeding tomatoes, a breeder might be interested in combining traits like uniform ripening, low soluble solids, and susceptibility to Tobacco Mosaic Virus (TMV) from "Parent A" with continuous ripening, high soluble solids, resistance to TMV, and low yield from "Parent B".

2. Cross these two plants. This involves emasculating the female parent, collecting pollen from the male parent, and then pollinating the female parent by hand

3. Collect seed and grow up progeny.

4. Evaluate performance of the progeny in subsequent generations. The decision on which generation to evaluate depends on the specific breeding scheme being used. This evaluation is carried out over several years and at many sites to ensure that the selected varieties perform reliably

5. Select the best progeny after evaluating their performance.

6. Propagate the improved variety. This can involve either the production of seed or through asexual propagation.

7. File for a "Plant Variety Patent" or a normal utility patent to protect the invention.

In a simple breeding example aiming to combine two simply inherited traits, each controlled by one gene, what is the expected proportion of progeny that will contain the combination of genes necessary to express both traits? a) 1 out of 4 b) 1 out of 8 c) 1 out of 16 d) 1 out of 32

c) 1 out of 16. This illustrates the challenge of combining traits even in a simple scenario, showing the power of independent assortment.

Why is plant breeding considered both an art and a science? a) Because it relies solely on intuition. b) Because it involves both creative vision in selecting parents and scientific principles of genetics. c) Because it only requires scientific knowledge, but is often done in a picturesque setting. d) Because it involves painting new colors onto flowers.

b) Because it involves both creative vision in selecting parents and scientific principles of genetics. It's not just about crunching numbers; it requires a keen eye and intuition for what combinations might work best, combined with a deep understanding of genetic inheritance.

Most characteristics important for horticulture, such as yield, flavor, and stress tolerance, are influenced by many genes. What term describes these traits? a) Monogenic traits b) Qualitative traits c) Polygenic or quantitative traits d) Mendelian traits

c) Polygenic or quantitative traits. This means many genes contribute to the final expression, making them much more challenging to breed for, as their inheritance is complex.

If a breeder wants to combine traits from two lines where each is controlled by five genes, what is the approximate frequency with which all ten desired genes will be present in the progeny of a cross between these? a) 1 in a thousand b) 1 in ten thousand c) 1 in a hundred thousand d) 1 in a million

d) 1 in a million. This really underscores the difficulty and the "needle in a haystack" aspect of breeding for multiple quantitative traits.

Which of the following crops is NOT typically grown as an inbred line and capable of self-pollination? a) Beans b) Tomato c) Petunia d) Apple

d) Apple. Apple is explicitly mentioned as a natural outcrosser, unlike beans, tomato, and petunia, which are typically self-pollinated.

What does it mean for a self-pollinated crop to be grown as an inbred line? a) All genes are heterozygous. b) Both alleles of each gene are the same (homozygous). c) The plants are sterile. d) They are prone to inbreeding depression.

b) Both alleles of each gene are the same (homozygous). This means the genetic makeup is very uniform and stable, leading to consistent traits from generation to generation.

For self-pollinated crops, what is true about their traits from generation to generation? a) They are highly variable. b) They are stably inherited. c) They depend heavily on environmental variation. d) They show significant inbreeding depression.

b) They are stably inherited. Because they are inbred and homozygous, their traits remain consistent across generations, which is valuable for predictable crop production.

What is a key step in the breeding process for self-pollinated crops after the F1 hybrid stage? a) Immediate asexual propagation. b) F2, segregation, followed by evaluation of families in later generations (F3, F4). c) Crossing with outcrossing crops. d) Introduction of polyploidy.

b) F2, segregation, followed by evaluation of families in later generations (F3, F4). This is where you see the traits separate out, and you can start selecting for the desired combinations.

Which of the following is a horticultural crop mentioned as a natural outcrosser? a) Petunia b) Tomato c) Rose d) Bean

c) Rose. Along with apple, roses are examples of crops that naturally cross-pollinate with other individuals.

What is a biological barrier that some outcrossing crops have to self-fertilization? a) Heterosis b) Incompatibility c) Hybrid vigor d) Homozygosity

b) Incompatibility. This mechanism prevents self-pollination, promoting genetic diversity through outcrossing.

What can result from self-pollination in many outcrossing crops? a) Increased vigor b) Higher productivity c) Hybrid vigor d) Reduced plant performance, vigor, or productivity (inbreeding depression)

d) Reduced plant performance, vigor, or productivity (inbreeding depression). Outcrossing species often suffer when forced to self-pollinate due to the expression of deleterious recessive alleles.

In outcrossing crop breeding, the F1 generation is genetically unique because: a) Each F1 plant inherits identical sets of genes from each parent. b) Each F1 plant inherits different sets of genes from each parent. c) They are entirely homozygous. d) They are the result of asexual propagation.

b) Each F1 plant inherits different sets of genes from each parent. This genetic diversity within the F1 is then leveraged through selection and asexual propagation.

Who first described the phenomenon of hybrids between inbred lines performing better than the inbreds themselves? a) Gregor Mendel b) Charles Darwin c) Nikolai Vavilov d) Luther Burbank

b) Charles Darwin. It’s fascinating how many fundamental biological concepts he observed, even beyond his work on natural selection.

What is the phenomenon where hybrids are more vigorous and have higher yield than their inbred parents called? a) Inbreeding depression b) Genetic uniformity c) Hybrid vigor or heterosis d) Polyploidy

c) Hybrid vigor or heterosis. This is a very powerful tool in plant breeding, leading to significantly improved performance.

Which of the following is an agronomic crop where F1 hybrids are widely used? a) Tomato b) Petunia c) Snapdragon d) Corn

d) Corn. F1 hybrid corn has dramatically increased yields, making it a staple crop worldwide.

Besides hand pollination, what genetic system is sometimes used to force cross-pollination for F1 hybrid seed production? a) Self-incompatibility b) Male-sterile lines c) Inducing polyploidy d) Germplasm collections

b) Male-sterile lines. This prevents the female parent from self-pollinating, ensuring that all seeds produced are true hybrids from the desired cross.

What is still debated regarding F1 hybrids? a) Whether they are more vigorous than inbreds. b) Their potential for asexual propagation. c) The basis of hybrid vigor. d) Their ability to be patented.

c) The basis of hybrid vigor. Despite its widespread use, the exact genetic mechanisms behind heterosis are still a subject of ongoing research.

Plant breeding is described as a progressive process because it involves: a) Revolutionary changes in a single generation. b) Large, discontinuous leaps in improvement. c) Small but continual improvements to established varieties. d) Primarily restoring wild traits to domesticated plants.

c) Small but continual improvements to established varieties. It's often a gradual process of refinement, building upon previous successes.

A large proportion of increased crop plant yields over the last 100 years is a result of plant breeding, but what other factor also contributes significantly to gains? a) Reduction in global cultivated land. b) Improved production practices (e.g., fertilization, pest control). c) Decreased genetic diversity. d) Spontaneous natural mutations.

b) Improved production practices (e.g., fertilization, pest control). It's a combination of better plants and better ways to grow them that leads to increased yields.

Why is the preservation of genetic diversity critical to plant breeding? a) It ensures that all plants are uniform. b) It reduces the need for new breeding efforts. c) It provides the raw material (variation) for future improvement. d) It eliminates the possibility of disease outbreaks.

c) It provides the raw material (variation) for future improvement. Without a diverse genetic pool, breeders have fewer options for developing new traits, like disease resistance or drought tolerance.

What are "germplasm collections" used for? a) To study plant diseases in isolation. b) To preserve genetic diversity of wild and cultivated varieties of crop plants. c) To develop new synthetic chemicals for plant growth. d) To store agricultural machinery.

b) To preserve genetic diversity of wild and cultivated varieties of crop plants. These collections are like living libraries of genetic potential, safeguarding the future of agriculture.

Who is credited with identifying the geographical centers of origin of various crop plants? a) Charles Darwin b) Gregor Mendel c) Nikolai Vavilov d) Luther Burbank

c) Nikolai Vavilov. His work on centers of origin is foundational to understanding crop diversity and where to look for valuable genetic material.

Which crop is listed as having its center of origin in the region associated with Maize, peppers, beans, and squash? a) Potatoes b) Rice c) Wheat d) None of the above; Maize, peppers, beans, squash are a grouping.

d) None of the above; Maize, peppers, beans, squash are a grouping. The list groups these crops together as originating from a specific geographical center (Mesoamerica).

From which geographical center of origin are potatoes, tomatoes, and peanuts associated? a) China b) South America c) Ethiopia d) Mediterranean

b) South America. This is the region where these important crops first evolved and were domesticated.

Which crop is specifically mentioned as originating from a center that also includes soybeans and sugarcane? a) Bananas b) Rice c) Wheat d) None of the above; Soybeans and sugarcane are a grouping.

d) None of the above; Soybeans and sugarcane are a grouping. These are grouped together as originating from a specific center, likely Southeast Asia.

What is the name of the cultivated apple species susceptible to apple scab? a) Malus floribunda b) Malus domestica c) Lycopersicon esculentum d) Lycopersicon pimpinellifolium

b) Malus domestica. This is the common apple we eat, and it faces challenges like scab.

From which related species can a gene for resistance to apple scab be transferred into cultivated apple? a) Lycopersicon esculentum b) Malus domestica c) Malus floribunda (crabapple) d) Sorghum

c) Malus floribunda (crabapple). This is a classic example of using wild relatives to introduce valuable traits into cultivated crops.

What method is used to transfer the scab resistance gene from crabapple into cultivated apple? a) Direct genetic modification b) Spontaneous mutation c) Sexual hybridization d) Asexual propagation only

c) Sexual hybridization. This involves traditional breeding methods, allowing the genetic material to be combined naturally.

In the process of introgressing the scab resistance gene into cultivated apple, after the F1 generation, what is the next step repeated multiple times? a) Self-pollination of F1 plants. b) Crossing the F1 plants back to the susceptible cultivated apple (Malus domestica). c) Crossing the F1 plants to the crabapple (Malus floribunda). d) Inducing polyploidy in the F1 plants.

b) Crossing the F1 plants back to the susceptible cultivated apple (Malus domestica). This "backcross" strategy is key to recovering most of the desirable traits of the cultivated apple while retaining the resistance gene.

Why is the backcross procedure repeated several times when introgressing genes from a wild relative into a cultivated species? a) To increase the frequency of the wild relative's undesirable traits. b) To recover most of the traits found in the regular cultivated apple. c) To make the plants resistant to all diseases. d) To reduce the overall genetic diversity.

b) To recover most of the traits found in the regular cultivated apple. You want the beneficial gene from the wild relative, but you also want to keep all the good traits (like large fruit, flavor) of the cultivated variety.

Each generation in the gene introgression process for apple scab resistance is noted to take how long? a) Several months b) Several years c) A single season d) A decade

b) Several years. This highlights the patience and long-term commitment required for traditional plant breeding, especially with tree crops.

From which wild relative have several genes for disease resistance been transferred into cultivated tomato (Lycopersicon esculentum)? a) Malus domestica b) Malus floribunda c) Lycopersicon pimpinellifolium d) Solanum tuberosum

c) Lycopersicon pimpinellifolium. This wild relative has been a valuable source of resistance genes for important tomato diseases.

What do the letters "VFNT" in improved tomato varieties indicate? a) Resistance to specific pests only. b) Enhanced flavor and nutritional traits. c) Genes for resistance to verticillium, fusarium, nematodes, and tomato mosaic virus. d) Varieties developed through natural selection only.

c) Genes for resistance to verticillium, fusarium, nematodes, and tomato mosaic virus. This acronym summarizes the multiple disease resistances introgressed from wild species.

New methods of biotechnology allow genes to be transferred from any species for plant improvement. True or False?

True. This is a significant advancement beyond traditional breeding, which is limited by the ability of species to hybridize sexually. Biotechnology overcomes this barrier.

Which of the following is NOT an example of plant improvement made possible by new biotechnology methods? a) Tomatoes with longer shelf life. b) Flowers that last longer. c) Plants that are resistant to viruses. d) Introduction of polyploidy for larger fruit.

d) Introduction of polyploidy for larger fruit. While polyploidy is a method of plant improvement, it's a traditional breeding strategy and not specifically listed as a new biotechnology method for gene transfer from any species.

"Functional foods" are an example of improved nutritional qualities made possible by which type of plant improvement? a) Sports b) Polyploidy c) Hybridization of self-pollinated crops d) New methods of biotechnology

d) New methods of biotechnology. Biotechnology allows for precise genetic modifications to enhance nutritional content, creating foods with added health benefits.

What are the two fundamental steps described in the summary for how plant breeding creates new plant varieties? a) Random mutation and natural selection. b) Deliberate crosses between selected parental lines and selection of elite lines. c) Environmental modification and nutrient enhancement. d) Mass propagation and commercialization.

b) Deliberate crosses between selected parental lines and selection of elite lines. This succinctly captures the essence of the entire breeding process.

What does the development of new methods of biotechnology expand the potential to develop? a) Plants with fewer genes. b) Plants that can only grow in controlled environments. c) Plants with novel characteristics. d) Plants that are identical to their wild ancestors.

c) Plants with novel characteristics. Biotechnology opens up a world of possibilities for creating traits that wouldn't be possible through traditional breeding alone.

What horticultural trait, important for ornamental crops, refers to the color variations found on leaves? a) Fall color b) Leaf retention c) Variegation d) Foliar longevity

c) Variegation. This is a highly sought-after aesthetic trait in many ornamental plants, often arising from chimeras.

Plant selection in horticultural crops is performed on a _ range of traits compared to other forms of selection. a) narrower b) wider c) similar d) unpredictable

b) wider. Horticultural crops are valued for many aesthetic and quality traits beyond just yield, leading to a broader focus in selection.

In human examples of deleterious alleles, which disease is mentioned as being caused by a genetic defect? a) Alzheimer's disease b) Diabetes c) Cystic fibrosis d) Heart disease

c) Cystic fibrosis. This specific example helps illustrate the impact of some genetic variations.

Which part of the genetic information flow (DNA -> RNA -> protein) is responsible for carrying out most essential functions in all organisms? a) DNA b) RNA c) Protein d) Genes

c) Protein. They are the molecular machines that perform the vast array of tasks necessary for life.

If a plant has a genetic makeup where both alleles of almost all its genes are the same, it is said to be: a) Heterozygous b) Polyploid c) Homozygous d) Triploid

c) Homozygous. This is characteristic of inbred lines, leading to stable inheritance.

The term 'heterosis' is synonymous with what other concept in plant breeding? a) Inbreeding depression b) Genetic uniformity c) Hybrid vigor d) Environmental variation

c) Hybrid vigor. These terms are used interchangeably to describe the superior performance of F1 hybrids.

In the context of improved tomato varieties, the 'N' in VFNT stands for resistance to which specific pathogen? a) Fungi b) Nematodes c) Nitrogen deficiency d) Nutritional imbalances

b) Nematodes. It’s important to know what each letter represents in such acronyms for disease resistance.

Plant improvement began with the identification of plants that could be reliably cultivated, harvested, and _. a) Marketed b) Stored c) Cross-pollinated d) Genetically modified

b) Stored. The ability to store harvested crops reliably was essential for ensuring a consistent food supply and the establishment of agriculture.