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Selective breeding, also known as artificial selection, is a process where humans intentionally choose specific animal or plant males and females to sexually reproduce to enhance desirable phenotypic traits in their offspring.
Answer: True
Explanation: Selective breeding, or artificial selection, is precisely defined as the intentional human selection of specific individuals for reproduction to enhance desired phenotypic traits in subsequent generations.
Domesticated animals resulting from selective breeding are known as varieties, while domesticated plants are referred to as breeds.
Answer: False
Explanation: The terminology is reversed; domesticated animals are known as breeds, while domesticated plants are referred to as varieties, cultigens, cultivars, or breeds.
When two purebred animals of different breeds reproduce, their offspring are called crossbreeds, and similarly, crossbred plants are known as hybrids.
Answer: True
Explanation: The terms 'crossbreeds' for animal offspring and 'hybrids' for plant offspring accurately describe the result of breeding two distinct purebred lineages.
Selective breeding can only occur through deliberate human intention and cannot happen unintentionally.
Answer: False
Explanation: Selective breeding can occur unintentionally as a byproduct of human cultivation practices, leading to changes in species without deliberate intent.
What is the primary goal of selective breeding, also known as artificial selection?
Answer: To intentionally choose specific males and females to enhance desirable phenotypic traits in offspring
Explanation: The fundamental objective of selective breeding is the deliberate human intervention in reproduction to propagate and intensify specific advantageous phenotypic characteristics across generations.
Domesticated animals resulting from selective breeding are known as breeds. What are domesticated plants referred to as?
Answer: Varieties, cultigens, cultivars, or breeds
Explanation: In the context of selective breeding, domesticated plants are classified as varieties, cultigens, cultivars, or breeds, distinguishing them from their wild progenitors.
What terms are used for the offspring when two purebred animals of different breeds reproduce, and for crossbred plants, respectively?
Answer: Crossbreeds and hybrids
Explanation: The offspring of two distinct purebred animal breeds are termed 'crossbreeds,' while crossbred plants are referred to as 'hybrids,' reflecting their mixed genetic heritage.
Can selective breeding occur unintentionally, and what might be one of its outcomes?
Answer: Yes, it can occur as a byproduct of human cultivation, potentially leading to desirable results like increased seed size
Explanation: Unintentional selective breeding can arise from human activities, such as cultivation practices, and may result in advantageous traits like increased seed size, highlighting the complex interplay between human action and evolutionary processes.
What is the term for the genetic mixing that occurs when distinct lineages are intentionally combined, resulting in offspring like crossbreeds or hybrids?
Answer: Crossbreeding
Explanation: Crossbreeding refers to the deliberate interbreeding of distinct genetic lineages, leading to the creation of offspring such as crossbreeds in animals or hybrids in plants.
Charles Darwin discussed the success of selective breeding in his 1859 book, 'On the Origin of Species', using artificial selection as an analogy to explain his theory of natural selection.
Answer: True
Explanation: Charles Darwin indeed used the concept of artificial selection, or selective breeding, as a foundational analogy in 'On the Origin of Species' to illustrate the principles of natural selection.
The practice of selective breeding is a modern invention, only dating back to the British Agricultural Revolution in the 18th century.
Answer: False
Explanation: Selective breeding has been practiced since prehistory, with significant alterations to species like wheat, rice, and dogs occurring over millennia, long before the British Agricultural Revolution.
Abu Rayhan Biruni, in the 11th century, expressed the notion of selective breeding in his book 'India' by providing examples such as an agriculturist selecting corn.
Answer: True
Explanation: Abu Rayhan Biruni's 11th-century work 'India' includes examples that illustrate the concept of selective breeding, such as an agriculturist choosing corn based on desired traits.
Robert Bakewell established selective breeding as a scientific practice during the British Agricultural Revolution, with his most significant breeding program focusing on cattle for milk production.
Answer: False
Explanation: While Robert Bakewell was instrumental in establishing selective breeding as a scientific practice, his most significant program focused on sheep for wool, and he was the first to breed cattle specifically for beef, not milk production.
Robert Bakewell improved the Lincoln Longwool sheep and subsequently developed the New (or Dishley) Leicester breed, known for being hornless and having a square, meaty body.
Answer: True
Explanation: Robert Bakewell's breeding efforts led to the improvement of the Lincoln Longwool and the development of the New Leicester breed, characterized by its hornless and meaty physique.
Robert Bakewell was the first to breed cattle specifically for beef, a departure from the previous practice of keeping cattle primarily as oxen for pulling ploughs.
Answer: True
Explanation: Robert Bakewell pioneered the breeding of cattle specifically for beef production, shifting from the traditional use of cattle as draught animals.
Robert Bakewell bred the Improved Black Cart horse, which later evolved into the Clydesdale horse.
Answer: False
Explanation: Robert Bakewell bred the Improved Black Cart horse, which later evolved into the Shire horse, not the Clydesdale.
Charles Darwin coined the term 'selective breeding' and used 'artificial selection' as an illustration of his proposed wider process of natural selection.
Answer: True
Explanation: Charles Darwin introduced the term 'selective breeding' and employed 'artificial selection' as a key analogy to elucidate his theory of natural selection in 'On the Origin of Species'.
The Romans practiced selective breeding, with treatises from 2,000 years ago offering advice on selecting animals for various purposes.
Answer: True
Explanation: Historical records, including Roman treatises, confirm the ancient practice of selective breeding, providing guidance on animal selection for specific purposes.
The average weight of a bull sold for slaughter more than doubled between 1700 and 1786 due to Robert Bakewell's cattle breeding efforts.
Answer: True
Explanation: Robert Bakewell's pioneering work in cattle breeding for beef production led to a dramatic increase in animal size, with the average weight of bulls more than doubling within a century.
Charles Darwin discussed selective breeding in his 1859 book, 'On the Origin of Species'. What was its purpose in his work?
Answer: To use artificial selection as an analogy to explain his theory of natural selection
Explanation: Darwin employed artificial selection as a compelling analogy to elucidate the mechanisms of natural selection, demonstrating how selective pressures, whether human-directed or environmental, drive evolutionary change.
What historical evidence supports the practice of selective breeding since prehistory?
Answer: Significant alteration of species like wheat, rice, and dogs from their wild ancestors over millennia
Explanation: The profound morphological changes observed in domesticated species such as wheat, rice, and dogs, when compared to their wild ancestors, provide compelling evidence for the ancient practice of selective breeding.
How did Abu Rayhan Biruni contribute to the concept of selective breeding in the 11th century?
Answer: He provided examples of selection, such as an agriculturist choosing corn or a forester choosing branches
Explanation: Abu Rayhan Biruni's 11th-century writings illustrate the concept of selective breeding through practical examples of human selection in agriculture and forestry.
Who established selective breeding as a scientific practice during the British Agricultural Revolution, and what was his primary focus?
Answer: Robert Bakewell, primarily focusing on sheep to select for large, fine-boned animals with lustrous wool
Explanation: Robert Bakewell is recognized for systematizing selective breeding during the British Agricultural Revolution, with a primary focus on improving sheep breeds for desirable wool and body characteristics.
Robert Bakewell improved the Lincoln Longwool sheep and subsequently developed which new breed?
Answer: The New (or Dishley) Leicester breed
Explanation: Robert Bakewell's breeding expertise led to the development of the New (or Dishley) Leicester breed, an improved lineage of sheep known for specific physical traits.
What was a significant impact of Robert Bakewell's work on cattle breeding?
Answer: He was the first to breed cattle specifically for beef, leading to a dramatic increase in size and quality
Explanation: Robert Bakewell revolutionized cattle breeding by focusing on beef production, a departure from traditional uses, which significantly enhanced the size and quality of livestock.
Robert Bakewell also bred the Improved Black Cart horse, which later evolved into what well-known draft horse breed?
Answer: The Shire horse
Explanation: The Improved Black Cart horse, developed by Robert Bakewell, is recognized as the progenitor of the modern Shire horse, a prominent draft breed.
How did Charles Darwin use the term 'artificial selection' in 'On the Origin of Species'?
Answer: As an illustration of his proposed wider process of natural selection, showing how humans select for desirable traits
Explanation: Darwin strategically employed the concept of artificial selection to provide a tangible and understandable parallel for the more abstract process of natural selection, emphasizing the role of selective pressures in shaping species.
What was the average weight of a bull sold for slaughter in 1700 compared to 1786, following Bakewell's breeding efforts?
Answer: It more than doubled
Explanation: Robert Bakewell's innovative cattle breeding practices led to a dramatic increase in the average weight of bulls, more than doubling between 1700 and 1786, signifying a major advancement in livestock production.
What did Robert Bakewell aim to select for in his most significant breeding program focused on sheep?
Answer: Large, fine-boned animals with long, lustrous wool
Explanation: Robert Bakewell's pioneering sheep breeding program aimed to develop animals with specific desirable traits, including large size, fine bones, and high-quality, lustrous wool.
Purebred animals are developed by selecting individuals with undesirable traits for further breeding and culling those with desired traits.
Answer: False
Explanation: Purebred animals are developed by selecting individuals with *desired* traits for further breeding and *culling* those with undesirable traits, ensuring the consistent transmission of specific characteristics.
Crossbreeds are a mix of two purebred animals with known parentage, whereas mixed breeds are a mix of several breeds, often with unknown or complex parentage.
Answer: True
Explanation: The distinction between crossbreeds and mixed breeds lies in the known parentage from two specific purebreds for crossbreeds, versus the often unknown or complex multi-breed parentage of mixed breeds.
The primary goal of purebred animal breeding is to introduce maximum genetic diversity into a lineage to prevent any degree of inbreeding.
Answer: False
Explanation: The primary goal of purebred breeding is to establish and maintain stable traits, often involving a degree of inbreeding, rather than maximizing genetic diversity.
Hybrid vigor, also known as heterosis, refers to the decreased strength, growth, and fertility often seen in hybrid offspring compared to their purebred parents.
Answer: False
Explanation: Hybrid vigor, or heterosis, actually refers to the *increased* strength, growth, and fertility observed in hybrid offspring compared to their purebred parents.
Plant breeding has been practiced for thousands of years, beginning with the domestication of wild plants into uniform agricultural cultigens, which was crucial for humans to transition to settled farming.
Answer: True
Explanation: The domestication of wild plants through selective breeding over millennia was a pivotal development, enabling the transition to settled agriculture and the establishment of stable food sources.
'Play farming' refers to an early period where humans fully committed all their time and resources to agriculture, minimizing the risk of crop failure.
Answer: False
Explanation: 'Play farming' describes an experimental phase of agriculture where humans did not fully commit resources due to the risk of crop failure, allowing for gradual acclimation and evolution of crops.
Michael Pollan's 'The Botany of Desire' illustrates coevolution by showing how human desires have influenced plants, and how these plants have, in turn, influenced humans.
Answer: True
Explanation: Michael Pollan's 'The Botany of Desire' explores the concept of coevolution, demonstrating the reciprocal influence between human desires and the selective breeding of plants.
What are the defining characteristics of animals known as particular breeds or pure breeds?
Answer: Homogeneous appearance, behavior, and other characteristics, developed by culling undesirable traits and selecting desired ones
Explanation: Purebred animals are characterized by their consistent and predictable traits, which are meticulously maintained through the selective breeding of individuals exhibiting desired characteristics and the removal of those with undesirable ones.
What is the primary difference between crossbreeds and mixed breeds in animal breeding?
Answer: Crossbreeds are a mix of two purebred animals with known parentage, while mixed breeds have unknown or complex parentage from several breeds
Explanation: The key distinction lies in the clarity of lineage: crossbreeds result from the intentional pairing of two known purebreds, whereas mixed breeds typically have a more complex and often undocumented multi-breed ancestry.
What is the main objective of purebred animal breeding?
Answer: To establish and maintain stable traits that animals will consistently pass on to the next generation
Explanation: The primary goal of purebred animal breeding is to ensure the consistent inheritance of specific, desirable traits, thereby maintaining the integrity and predictability of the breed's characteristics.
Hybrid vigor, or heterosis, refers to what characteristic often seen in hybrid offspring compared to their purebred parents?
Answer: Increased strength, growth, and fertility
Explanation: Hybrid vigor, or heterosis, describes the phenomenon where hybrid offspring often exhibit superior strength, growth, and fertility compared to their purebred parents, a beneficial outcome of genetic outcrossing.
How has plant breeding evolved over thousands of years, starting from wild plants?
Answer: By domesticating wild plants into uniform and predictable agricultural cultigens, leading to high-yielding varieties
Explanation: Plant breeding has a long history, characterized by the gradual domestication of wild species into cultivated forms with enhanced yields and predictable characteristics, a process fundamental to the development of agriculture.
What was 'play farming' and how did it influence early agriculture?
Answer: An experimental approach where humans cultivated plants without fully committing all resources, allowing crops to acclimate and evolve
Explanation: 'Play farming' represents an early, less intensive phase of agriculture, where experimental cultivation allowed crops to adapt and co-evolve with human practices before full commitment to settled farming.
In 'The Botany of Desire,' Michael Pollan illustrates coevolution by showing how human desires have influenced plants, and in turn, how these plants have influenced humans. Which of the following is NOT an example he uses?
Answer: Wheat for disease resistance
Explanation: Michael Pollan's 'The Botany of Desire' explores coevolution through examples such as apples, tulips, cannabis, and potatoes, but does not specifically cite wheat for disease resistance in this context.
What is the term for animals with homogeneous appearance, behavior, and other characteristics, developed by culling undesirable traits and selecting desired ones?
Answer: Pure breeds
Explanation: Animals exhibiting consistent and uniform characteristics, achieved through rigorous selection and culling, are classified as pure breeds, representing a stable genetic lineage.
The potential benefits of selective breeding in aquaculture were realized early due to low mortality rates and extensive education in quantitative genetics among fish biologists.
Answer: False
Explanation: The potential benefits of selective breeding in aquaculture were delayed due to high mortality rates, inbreeding depression, difficulties in controlling reproduction, and a lack of education in quantitative genetics.
Aquaculture species are selectively bred for key quality traits such as growth rate, survival rate, meat quality, and age at sexual maturation.
Answer: True
Explanation: Aquaculture breeding programs prioritize traits such as growth rate, survival, meat quality, and age at sexual maturation to enhance productivity and economic viability.
Selective breeding has led to a 30% decrease in body weight per generation for Atlantic salmon.
Answer: False
Explanation: Selective breeding has resulted in a *30% increase* in body weight per generation for Atlantic salmon, not a decrease.
Rainbow trout have shown substantial improvements in growth rate and high resistance to Infectious Pancreatic Necrosis Virus (IPNV) through selective breeding.
Answer: True
Explanation: Selective breeding programs have successfully enhanced growth rates and conferred high resistance to IPNV in rainbow trout, demonstrating significant improvements in aquaculture.
Coho salmon have shown a decrease in weight after four generations of selective breeding, but earlier spawning dates were successfully achieved.
Answer: False
Explanation: Coho salmon have shown a *more than 60% increase* in weight after four generations of selective breeding, in addition to achieving earlier spawning dates.
Selective breeding programs for Common carp aim to improve growth, body shape, and disease resistance, leading to outcomes like improved cold tolerance in some strains.
Answer: True
Explanation: Common carp breeding programs successfully target improved growth, body shape, and disease resistance, with notable achievements such as enhanced cold tolerance in specific strains like the Ropsha carp.
Selective breeding has led to an approximate 80% increase in growth rate per generation for Channel Catfish.
Answer: False
Explanation: Selective breeding has led to an approximate 80% *response to selection* for improved growth rate, averaging a *13% increase per generation* for Channel Catfish, not an 80% increase per generation.
Selective breeding for live weight in Pacific oysters has resulted in improvements up to 25.6% compared to wild stock, and Sydney-rock oysters showed a 15% increase after two generations.
Answer: True
Explanation: Significant improvements in live weight have been achieved through selective breeding in both Pacific and Sydney-rock oysters, demonstrating the efficacy of these programs.
Selective breeding programs have successfully developed resistance to the Bonamia ostreae parasite in European flat oysters, leading to lower infection prevalence and reduced mortality.
Answer: True
Explanation: Selective breeding has proven effective in enhancing resistance to the Bonamia ostreae parasite in European flat oysters, mitigating the impact of this significant pathogen.
Researchers successfully bred the Eastern oyster for dual resistance against co-occurring parasites Haplosporidium nelson (MSX) and Perkinsus marinus (Dermo).
Answer: True
Explanation: The Eastern oyster has been successfully bred for dual resistance to MSX and Dermo parasites, showcasing the potential of selective breeding to address complex disease challenges in aquaculture.
Selective breeding for growth in Litopenaeus stylirostris showed an 18% decrease in growth after the fourth generation.
Answer: False
Explanation: Selective breeding for growth in Litopenaeus stylirostris resulted in an *18% increase* in growth after the fourth generation, not a decrease.
Selective breeding has been effective in combating viral diseases in Penaeid shrimps, developing Pacific White Shrimp with increased survival to TSV and 'Super Shrimp' resistant to IHHNV.
Answer: True
Explanation: Selective breeding has yielded significant success in developing shrimp strains with enhanced resistance to major viral diseases like TSV and IHHNV, crucial for sustainable aquaculture.
Selective breeding programs for aquatic species often show better outcomes than those for terrestrial livestock primarily due to their low fecundity and limited genetic variation.
Answer: False
Explanation: Aquatic species breeding programs often show better outcomes due to their *high fecundity* and *large phenotypic and genetic variation*, which allow for greater selection intensity.
The primary economic benefits of selective breeding in aquaculture include reduced production costs due to faster turnover rates and improved feed efficiency.
Answer: True
Explanation: Selective breeding in aquaculture contributes to economic efficiency by accelerating growth rates, reducing maintenance, and improving feed conversion, thereby lowering overall production costs.
Why were the potential benefits of selective breeding in aquaculture not realized until recently?
Answer: High mortality rates in early programs led to inbreeding depression and reliance on wild stock
Explanation: The delayed realization of aquaculture's breeding potential was largely due to early challenges such as high mortality rates, which resulted in limited broodstock, inbreeding, and a continued dependence on wild populations.
Which of the following is a key quality trait for which aquaculture species are selectively bred?
Answer: Meat quality (e.g., size, fat percentage, color, taste)
Explanation: Meat quality, encompassing attributes like size, fat content, color, and taste, is a critical trait targeted in selective breeding programs for aquaculture species to meet consumer demands and market standards.
Selective breeding has significantly improved Atlantic salmon, leading to what percentage increase in body weight per generation?
Answer: 30%
Explanation: Selective breeding efforts have yielded substantial improvements in Atlantic salmon, notably a 30% increase in body weight per generation, alongside other enhanced performance metrics.
What improvements have been observed in rainbow trout through selective breeding?
Answer: Substantial improvements in growth rate and high resistance to IPNV
Explanation: Rainbow trout breeding programs have successfully achieved notable gains in growth rate and developed robust resistance to Infectious Pancreatic Necrosis Virus (IPNV), enhancing their viability in aquaculture.
What significant results have been achieved in selective breeding programs for Coho salmon?
Answer: More than a 60% increase in weight and earlier spawning dates
Explanation: Coho salmon breeding programs have demonstrated remarkable success, achieving over a 60% increase in weight and earlier spawning, contributing to more efficient production cycles.
Selective breeding programs for Common carp have aimed to improve growth, body shape, and disease resistance. What was a notable outcome for the Ropsha carp strain?
Answer: A 30-40% to 77.4% improvement in cold tolerance
Explanation: The Ropsha carp strain, developed through selective breeding, exemplifies successful adaptation to environmental stressors, exhibiting a significant improvement in cold tolerance.
What has been the approximate average increase in growth rate per generation for Channel Catfish due to selective breeding?
Answer: 13%
Explanation: Selective breeding has consistently yielded an average growth rate increase of approximately 13% per generation in Channel Catfish, contributing to enhanced productivity.
Selective breeding for live weight in Pacific oysters has resulted in improvements ranging from 0.4% to what maximum percentage compared to wild stock?
Answer: 25.6%
Explanation: Selective breeding programs have achieved substantial gains in Pacific oyster live weight, with improvements reaching up to 25.6% over wild stock, demonstrating significant genetic progress.
How have selective breeding programs successfully addressed the Bonamia ostreae parasite in European flat oysters?
Answer: By developing resistance in oysters, leading to lower infection prevalence and reduced mortality
Explanation: Selective breeding has been instrumental in developing oyster strains with enhanced resistance to the Bonamia ostreae parasite, effectively reducing disease impact and improving survival rates.
Researchers successfully bred the Eastern oyster, Crassostrea virginica, for dual resistance against which two co-occurring parasites?
Answer: Haplosporidium nelson (MSX) and Perkinsus marinus (Dermo)
Explanation: The Eastern oyster has been successfully bred to exhibit dual resistance against the prevalent MSX and Dermo parasites, a significant achievement in aquaculture disease management.
What were the results of selective breeding for growth in Litopenaeus stylirostris after the fourth generation?
Answer: An 18% increase
Explanation: Selective breeding for growth in Litopenaeus stylirostris demonstrated an 18% increase in growth after four generations, highlighting the effectiveness of these programs in shrimp aquaculture.
Selective breeding has helped Penaeid shrimps combat viral diseases by developing which resistant lines?
Answer: Pacific White Shrimp with increased survival to TSV and 'Super Shrimp' resistant to IHHNV
Explanation: Through selective breeding, Penaeid shrimps have developed enhanced resistance to critical viral pathogens, including TSV and IHHNV, leading to more resilient aquaculture stocks.
Selective breeding programs for aquatic species often show better outcomes compared to terrestrial livestock primarily due to:
Answer: High fecundity of both sexes and large phenotypic and genetic variation in aquatic species
Explanation: The superior outcomes in aquatic species breeding programs are largely attributable to their high fecundity and extensive genetic variation, which provide ample opportunities for intense selection.
Which of the following is a primary economic benefit of selective breeding in aquaculture?
Answer: Reduced production costs due to faster turnover rates and improved feed efficiency
Explanation: Selective breeding in aquaculture yields significant economic advantages by accelerating growth, enhancing feed efficiency, and reducing overall production expenses, thereby increasing profitability.
In modern research, selective plant breeding is used to produce transgenic animals that breed 'true' for artificially inserted or deleted genes.
Answer: True
Explanation: Modern research utilizes selective breeding techniques to create transgenic animals that reliably pass on specific genetic modifications, enabling the study of gene function across generations.
One of the main advantages of selective breeding as a research tool is that it provides a direct way to determine if a specific trait can evolve in response to selection, requiring fewer individuals for testing compared to single-generation experiments.
Answer: True
Explanation: Selective breeding serves as an effective research tool by directly demonstrating the evolutionary potential of traits under selection, often with greater efficiency than single-generation studies.
A practical advantage of selective breeding experiments is that a single experiment can assess an entire group of genetic variances, making them highly efficient.
Answer: False
Explanation: A practical disadvantage of selective breeding experiments is that they require individual experiments for each specific trait, as a single experiment cannot assess an entire group of genetic variances.
What is a modern application of selective plant breeding in research?
Answer: To produce transgenic animals that breed 'true' for artificially inserted or deleted genes
Explanation: A contemporary application of selective breeding in research involves generating transgenic animals that reliably transmit specific genetic modifications, facilitating the study of gene function and inheritance.
What is one of the main advantages of using selective breeding as a research tool?
Answer: It provides a direct way to determine if a specific trait can evolve in response to selection, requiring fewer individuals than single-generation breeding
Explanation: Selective breeding offers a direct and efficient method for researchers to ascertain the evolutionary potential of specific traits under selection, particularly for complex characteristics, often requiring fewer subjects than alternative approaches.
Which of the following is a practical disadvantage of conducting selective breeding experiments?
Answer: They require individual experiments for every specific trait and often controlled environments
Explanation: A practical limitation of selective breeding experiments is the necessity for trait-specific studies and the often demanding requirement for controlled environmental conditions and mating protocols, which can be resource-intensive.
Single-trait breeding, focusing on one characteristic, can lead to problematic outcomes such as roosters losing the ability to perform courtship dances or lab rats developing severe neurosis.
Answer: True
Explanation: Focusing selective breeding on a single trait can have unintended negative consequences, as demonstrated by the behavioral and neurological issues observed in roosters and lab rats.
Selective breeding in aquaculture always enhances genetic diversity in wild fish populations by introducing new, beneficial traits.
Answer: False
Explanation: Selective breeding in aquaculture can negatively impact wild fish populations by reducing genetic diversity in farmed stock and potentially through interbreeding with or competition from escaped farmed fish.
Selective breeding in dogs, particularly for extremely small sizes, has been linked to a higher incidence of kneecap dislocations.
Answer: True
Explanation: The pursuit of extreme physical traits through selective breeding, such as very small size in dogs, can lead to increased prevalence of specific health issues like kneecap dislocations.
The Lenape potato was selectively bred for enhanced flavor, but it inadvertently resulted in dangerously high levels of toxic glycoalkaloid solanine.
Answer: False
Explanation: The Lenape potato was selectively bred for *disease and pest resistance*, not enhanced flavor, and this resistance was linked to dangerously high levels of toxic glycoalkaloid solanine.
The reduction of genetic diversity due to selective breeding can make crop populations highly vulnerable to mass epidemics, as exemplified by the Southern Corn leaf-blight epidemic of 1970.
Answer: True
Explanation: The Southern Corn leaf-blight epidemic of 1970 serves as a stark example of how reduced genetic diversity, a consequence of selective breeding, can render crop populations highly susceptible to widespread disease.
What potential problem can arise from single-trait breeding, as exemplified by roosters bred solely for fast growth?
Answer: Loss of ability to perform courtship dances, leading to aggression towards hens
Explanation: Single-trait breeding, such as prioritizing rapid growth, can inadvertently compromise other essential behaviors, leading to maladaptive outcomes like the loss of courtship rituals and increased aggression in roosters.
What is a potential negative impact of selective breeding in aquaculture on biodiversity?
Answer: Loss of genetic diversity in farmed stock and potential negative impacts on wild populations through competition or interbreeding
Explanation: A significant ecological concern associated with aquaculture selective breeding is the potential for reduced genetic diversity in farmed populations and adverse effects on wild populations through genetic introgression or competitive exclusion.
What physical problem is specifically mentioned as arising from selective breeding in dogs, particularly for extremely small sizes?
Answer: Kneecap dislocations
Explanation: Selective breeding for extreme miniaturization in dog breeds has been associated with an elevated incidence of patellar luxation (kneecap dislocations), highlighting a trade-off between aesthetic traits and health.
Which plant was selectively bred for disease resistance but resulted in dangerously high levels of toxic glycoalkaloid solanine?
Answer: The Lenape potato
Explanation: The Lenape potato, bred for disease resistance, inadvertently accumulated toxic levels of solanine, underscoring the potential for unintended harmful consequences in selective breeding programs.
The reduction of genetic diversity due to selective breeding can severely impact crop populations by:
Answer: Making them vulnerable to mass epidemics, as seen with the Southern Corn leaf-blight
Explanation: Reduced genetic diversity, a common outcome of intensive selective breeding, can critically compromise crop resilience, rendering populations highly susceptible to widespread disease outbreaks, as tragically demonstrated by the Southern Corn leaf-blight epidemic.
The image of the Belgian Blue cow illustrates how selective breeding can maintain specific genetic defects, such as a myostatin gene defect, for accelerated lean muscle growth.
Answer: True
Explanation: The Belgian Blue cow exemplifies how selective breeding can perpetuate specific genetic traits, even defects like the myostatin gene, to achieve desired agricultural outcomes such as increased muscle mass.
The image comparing a Chihuahua mix and a Great Dane demonstrates the limited range of dog breed sizes that can be created through selective breeding within a single species.
Answer: False
Explanation: The comparison of a Chihuahua mix and a Great Dane actually demonstrates the *wide range* of dog breed sizes achievable through selective breeding within a single species, highlighting extreme variations.
The image showing teosinte and modern maize represents the dramatic transformation achieved through selective breeding, altering wild plants to develop high-yielding agricultural crops.
Answer: True
Explanation: The visual evolution from teosinte to modern maize serves as a powerful illustration of the profound morphological and yield-related transformations achieved through millennia of human selective breeding.
The image of carrots of many colors signifies that selective breeding is limited to producing only orange carrots.
Answer: False
Explanation: The existence of multi-colored carrots demonstrates that selective breeding can be utilized to develop a diverse range of aesthetic and nutritional traits in plants, extending beyond a single color.
The Belgian Blue cow illustrates how selective breeding can maintain which specific genetic characteristic?
Answer: A myostatin gene defect responsible for accelerated lean muscle growth
Explanation: The Belgian Blue cow serves as a prominent example of how selective breeding can perpetuate a specific genetic defect, the myostatin gene, to achieve a desired phenotype of extreme muscle mass.
The comparison of a Chihuahua mix and a Great Dane demonstrates what about selective breeding in dogs?
Answer: The wide range of dog breed sizes created through human selection for specific physical characteristics
Explanation: The dramatic size disparity between a Chihuahua mix and a Great Dane vividly illustrates the extensive phenotypic plasticity achievable within a single species through human-directed selective breeding for diverse physical attributes.
The image showing teosinte and modern maize represents the dramatic transformation achieved through selective breeding, specifically:
Answer: The alteration of wild plants to develop high-yielding agricultural crops
Explanation: The morphological divergence from wild teosinte to modern maize is a classic example of how selective breeding has profoundly reshaped wild plant species into highly productive agricultural staples.
The image of carrots of many colors signifies that selective breeding can be used to:
Answer: Develop carrots with a variety of aesthetic and nutritional traits
Explanation: The successful breeding of multi-colored carrots demonstrates the capacity of selective breeding to diversify both the visual and nutritional characteristics of cultivated plants.