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Questions and Answers
Which plant family does Eragrostis tef belong to?
Which plant family does Eragrostis tef belong to?
What type of plant is Eragrostis tef?
What type of plant is Eragrostis tef?
Where was Eragrostis tef first domesticated?
Where was Eragrostis tef first domesticated?
What part of the plant is primarily used for food?
What part of the plant is primarily used for food?
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What is a common method of processing Eragrostis tef?
What is a common method of processing Eragrostis tef?
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What type of plant is arugula (Eruca vesicaria) classified as?
What type of plant is arugula (Eruca vesicaria) classified as?
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What part of arugula (Eruca vesicaria) is primarily used for consumption?
What part of arugula (Eruca vesicaria) is primarily used for consumption?
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Which of the following best describes the native distribution of arugula (Eruca vesicaria)?
Which of the following best describes the native distribution of arugula (Eruca vesicaria)?
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How is arugula (Eruca vesicaria) typically prepared for consumption?
How is arugula (Eruca vesicaria) typically prepared for consumption?
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Which of the following is NOT a characteristic of arugula (Eruca vesicaria)?
Which of the following is NOT a characteristic of arugula (Eruca vesicaria)?
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What primary factor did early plant classification systems focus on?
What primary factor did early plant classification systems focus on?
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Who created the first plant classification system that recognized distinct plant families?
Who created the first plant classification system that recognized distinct plant families?
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What issue did the use of common names in plant classification present?
What issue did the use of common names in plant classification present?
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Which innovation in the 17th century greatly aided plant classification?
Which innovation in the 17th century greatly aided plant classification?
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What does Linnaeus’ binomial system consist of?
What does Linnaeus’ binomial system consist of?
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What is the correct way to write a species name according to the International Code of Botanical Nomenclature?
What is the correct way to write a species name according to the International Code of Botanical Nomenclature?
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What limitation did the polynomial nomenclature have before Linnaeus' system?
What limitation did the polynomial nomenclature have before Linnaeus' system?
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In what context did Theophrastus’ classification system remain influential until the 17th century?
In what context did Theophrastus’ classification system remain influential until the 17th century?
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What defines a biological species in the context of plant classification?
What defines a biological species in the context of plant classification?
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Which type of classification is primarily used by plant taxonomists when dealing with species?
Which type of classification is primarily used by plant taxonomists when dealing with species?
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What is an example of a plant that has evolved a morphology to attract pollinators?
What is an example of a plant that has evolved a morphology to attract pollinators?
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How do environmental conditions affect plant morphology?
How do environmental conditions affect plant morphology?
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Which plant is known for having the world's largest flower?
Which plant is known for having the world's largest flower?
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What type of reproduction do dandelions primarily use?
What type of reproduction do dandelions primarily use?
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What distinguishes monocots from eudicots in terms of cotyledons?
What distinguishes monocots from eudicots in terms of cotyledons?
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Which characteristic is typical for monocots regarding their floral parts?
Which characteristic is typical for monocots regarding their floral parts?
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What is a feature of eudicot root systems?
What is a feature of eudicot root systems?
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What evolutionary theory is primarily recognized today regarding flowering plants?
What evolutionary theory is primarily recognized today regarding flowering plants?
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Which of the following features is generally true for both monocots and eudicots?
Which of the following features is generally true for both monocots and eudicots?
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Which statement about the magnoliid angiosperms is correct?
Which statement about the magnoliid angiosperms is correct?
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What is one hypothesized evolutionary result influenced by Hooker's theory?
What is one hypothesized evolutionary result influenced by Hooker's theory?
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In terms of leaf structure, what distinguishes monocots from eudicots?
In terms of leaf structure, what distinguishes monocots from eudicots?
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What characteristic of the Victoria Water Lily is essential for its survival?
What characteristic of the Victoria Water Lily is essential for its survival?
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Which feature is commonly emphasized in phenetic classification systems?
Which feature is commonly emphasized in phenetic classification systems?
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What evolutionary trait do Baobab trees exhibit to survive in their environment?
What evolutionary trait do Baobab trees exhibit to survive in their environment?
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What is a primary challenge in determining evolutionary relationships among flowering plants?
What is a primary challenge in determining evolutionary relationships among flowering plants?
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What characteristic is NOT typically assessed in phenetic classification systems?
What characteristic is NOT typically assessed in phenetic classification systems?
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Which flowering plant is known for growing in the foggy weather of Mt. Kilimanjaro?
Which flowering plant is known for growing in the foggy weather of Mt. Kilimanjaro?
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What significant development has enhanced our understanding of plant phylogenetics?
What significant development has enhanced our understanding of plant phylogenetics?
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What morphology does Azarella compacta exhibit?
What morphology does Azarella compacta exhibit?
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What is a major advantage of agriculture?
What is a major advantage of agriculture?
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Which region is associated with the earliest evidence of agricultural development?
Which region is associated with the earliest evidence of agricultural development?
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What theory proposed by Gordon Childe suggests a connection between humans and domesticated herd animals?
What theory proposed by Gordon Childe suggests a connection between humans and domesticated herd animals?
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According to Carl Sauer, where did human populations first establish a sedentary existence?
According to Carl Sauer, where did human populations first establish a sedentary existence?
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What is one proposed reason for the development of agriculture in arid regions?
What is one proposed reason for the development of agriculture in arid regions?
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What does the Neolithic Revolution refer to in the context of agriculture?
What does the Neolithic Revolution refer to in the context of agriculture?
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What type of species did Childe suggest might have developed due to human and animal interactions during dry periods?
What type of species did Childe suggest might have developed due to human and animal interactions during dry periods?
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What environmental conditions likely influenced the beginning of agriculture in different regions?
What environmental conditions likely influenced the beginning of agriculture in different regions?
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What practice was notably used by the Aztecs for agricultural development?
What practice was notably used by the Aztecs for agricultural development?
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Which genotype is favored due to its simultaneous seed maturation in the context of agricultural selection?
Which genotype is favored due to its simultaneous seed maturation in the context of agricultural selection?
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What selective pressure has contributed to a reduction in seed appendages in cultivated plants?
What selective pressure has contributed to a reduction in seed appendages in cultivated plants?
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What characteristic has been commonly selected for in cereal crops as a result of human harvesting practices?
What characteristic has been commonly selected for in cereal crops as a result of human harvesting practices?
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What trait has been selected against in wild grasses due to human agricultural practices?
What trait has been selected against in wild grasses due to human agricultural practices?
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What process is exemplified by the planting-harvesting link in agriculture?
What process is exemplified by the planting-harvesting link in agriculture?
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Which of the following best describes the effects of human cultivation on wild plant phenotypes?
Which of the following best describes the effects of human cultivation on wild plant phenotypes?
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What was a key reason for early human populations to transition from a hunter-gatherer lifestyle to agriculture?
What was a key reason for early human populations to transition from a hunter-gatherer lifestyle to agriculture?
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Which of the following describes a lifestyle characteristic of hunter-gatherer societies?
Which of the following describes a lifestyle characteristic of hunter-gatherer societies?
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What did sedentary agricultural life enable in terms of societal structure?
What did sedentary agricultural life enable in terms of societal structure?
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What aspect of plant domestication is considered crucial in understanding early agricultural development?
What aspect of plant domestication is considered crucial in understanding early agricultural development?
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How did hunter-gatherers' knowledge of plants influence their eventual shift to agriculture?
How did hunter-gatherers' knowledge of plants influence their eventual shift to agriculture?
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What main change occurred in human populations due to the advent of agriculture?
What main change occurred in human populations due to the advent of agriculture?
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What advantage does loss of shattering provide for crop plants?
What advantage does loss of shattering provide for crop plants?
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How does intraspecific competition affect seedling growth?
How does intraspecific competition affect seedling growth?
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What role do weeds play in the agricultural ecosystem during crop harvest?
What role do weeds play in the agricultural ecosystem during crop harvest?
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Which historical event significantly altered the global distribution of food plants?
Which historical event significantly altered the global distribution of food plants?
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What indigenous food plant is considered most notable from Asia?
What indigenous food plant is considered most notable from Asia?
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What was one of the Mediterranean species introduced to northern Europe by the Romans?
What was one of the Mediterranean species introduced to northern Europe by the Romans?
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Which of the following crops was introduced to Europe from South America?
Which of the following crops was introduced to Europe from South America?
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What effect do the introductions of new crops have on agriculture?
What effect do the introductions of new crops have on agriculture?
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What is a primary concern regarding genetically engineered (GE) crops in ecosystems?
What is a primary concern regarding genetically engineered (GE) crops in ecosystems?
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Which statement accurately differentiates genetic engineering from genetic modification?
Which statement accurately differentiates genetic engineering from genetic modification?
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How has the decline of older plant cultivars impacted agricultural practices?
How has the decline of older plant cultivars impacted agricultural practices?
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What is a significant reason for consumer resistance to GE crops, especially in Europe?
What is a significant reason for consumer resistance to GE crops, especially in Europe?
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What does the term 'genetic diversity' imply in agriculture?
What does the term 'genetic diversity' imply in agriculture?
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What is a potential effect of hybridizing GE crops with native plants?
What is a potential effect of hybridizing GE crops with native plants?
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Why are older crop varieties increasingly sought after by agricultural geneticists?
Why are older crop varieties increasingly sought after by agricultural geneticists?
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What is a key characteristic of white flour compared to whole grain flour?
What is a key characteristic of white flour compared to whole grain flour?
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Which proteins are essential for traditional bread-making?
Which proteins are essential for traditional bread-making?
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What is the significance of the corn plant having separate male and female flowers?
What is the significance of the corn plant having separate male and female flowers?
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What primary component is released by yeast during the fermentation of dough?
What primary component is released by yeast during the fermentation of dough?
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How does corn's protein content compare to other cereal grains?
How does corn's protein content compare to other cereal grains?
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Which type of bread can be made from corn flour due to the absence of gluten?
Which type of bread can be made from corn flour due to the absence of gluten?
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In what ways is modern corn beneficial in agriculture?
In what ways is modern corn beneficial in agriculture?
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What role did corn play in the development of ancient civilizations in Central America?
What role did corn play in the development of ancient civilizations in Central America?
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What is the main carbohydrate found in cereal grains?
What is the main carbohydrate found in cereal grains?
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Which term is used to describe the dry indehiscent fruit produced by true cereals?
Which term is used to describe the dry indehiscent fruit produced by true cereals?
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How many chromosomes are present in the final hexaploid form of bread wheat?
How many chromosomes are present in the final hexaploid form of bread wheat?
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What was the initial process used to make cereal grains edible 9,000 years ago?
What was the initial process used to make cereal grains edible 9,000 years ago?
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Where is bread wheat thought to have originated?
Where is bread wheat thought to have originated?
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Which of the following describes the process of backcrossing in the development of bread wheat?
Which of the following describes the process of backcrossing in the development of bread wheat?
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What is the primary use of durum wheat?
What is the primary use of durum wheat?
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Which of the following statements is true about the classification of wheat species?
Which of the following statements is true about the classification of wheat species?
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What significant event is thought to have led to the creation of leavened bread?
What significant event is thought to have led to the creation of leavened bread?
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What is the main function of the endosperm in wheat grain?
What is the main function of the endosperm in wheat grain?
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What processing step involves moistening the grain to toughen the bran?
What processing step involves moistening the grain to toughen the bran?
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What part of the wheat grain is primarily made up of starch?
What part of the wheat grain is primarily made up of starch?
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Which type of wheat is commonly grown in cool temperate regions and harvested in autumn?
Which type of wheat is commonly grown in cool temperate regions and harvested in autumn?
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What is the primary purpose of current breeding programs for wheat?
What is the primary purpose of current breeding programs for wheat?
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How does black stem rust fungus affect wheat plants?
How does black stem rust fungus affect wheat plants?
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Which grain is mainly grown as fodder and has the highest protein content among cereals?
Which grain is mainly grown as fodder and has the highest protein content among cereals?
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What health issue was linked to the consumption of polished white rice in the early 1900s?
What health issue was linked to the consumption of polished white rice in the early 1900s?
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What compound found in ergot can cause psychotic symptoms in humans?
What compound found in ergot can cause psychotic symptoms in humans?
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What characterizes rye flour in baking?
What characterizes rye flour in baking?
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Which vitamin deficiency is commonly associated with polished white rice consumption?
Which vitamin deficiency is commonly associated with polished white rice consumption?
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What is the primary use of oats in agriculture?
What is the primary use of oats in agriculture?
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How did the consumption of ergot-contaminated rye influence history?
How did the consumption of ergot-contaminated rye influence history?
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Which of the following statements about the breeding process for hybrid corn is true?
Which of the following statements about the breeding process for hybrid corn is true?
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What consequence did the male-sterility gene carry during hybrid corn breeding?
What consequence did the male-sterility gene carry during hybrid corn breeding?
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Which rice variety is known for requiring continuous submergence in water?
Which rice variety is known for requiring continuous submergence in water?
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How is labor typically involved in rice farming practices in Asia, Africa, and South America?
How is labor typically involved in rice farming practices in Asia, Africa, and South America?
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Which nutrient is specifically crucial for rice cultivation?
Which nutrient is specifically crucial for rice cultivation?
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What is a key characteristic that distinguishes hybrid rice cultivars from traditional ones?
What is a key characteristic that distinguishes hybrid rice cultivars from traditional ones?
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What type of rice is characterized as short-grained and tends to be sticky when boiled?
What type of rice is characterized as short-grained and tends to be sticky when boiled?
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Study Notes
Botanical Information
- Eragrostis tef belongs to the Poaceae family, commonly known as the grass family.
- It is an herbaceous annual plant.
- Its native distribution is in the Ethiopian highlands.
History as a Food Plant
- Tef was first domesticated in Ethiopia.
- It is most widely grown in Ethiopia and Eritrea.
Utilization
- The seeds of Eragrostis tef are used as a food source.
- They can be processed in various ways:
- Ground into flour for making injera, a flatbread that is a staple food in Ethiopia.
- Used to make other breads, porridges, and beverages.
- Sometimes consumed as a whole grain.
Botanical Information
-
Arugula belongs to the Brassicaceae family, also known as the mustard family.
-
Arugula is an herbaceous annual plant.
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Arugula is native to the Mediterranean region and parts of Central Asia.
Utilization
-
The leaves of the arugula plant are used as a food.
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Arugula leaves can be eaten raw in salads, sandwiches, or as a garnish. They can also be cooked in dishes like pasta or stir-fries.
History of Plant Classification
- Theophrastus, a disciple of Aristotle, created the first plant classification system around 2300 years ago. He identified key characteristics to distinguish natural plant groups, recognizing families like Pea, Grass, Sunflower, and Mustard.
- The Age of Herbals (1470-1670) saw the expansion of early works, following the invention of the printing press.
- Due to communication problems with common names, a standard Latin-based system of nomenclature was developed.
- Carl Linnaeus introduced the binomial system, still used today, in Species Plantarum (1753). In this system, the species name consists of a generic name and a species epithet.
- The system follows rules from the International Code of Botanical Nomenclature, including capitalization, italicization, and the use of authority designations.
Plant Species
- A biological species is a group of individuals that can interbreed with one another but not with individuals of another species.
- Plants are notoriously "plastic," meaning their morphology depends on the environmental conditions under which they are grown.
- Evolution is constantly altering morphological form.
- Examples of morphological diversity:
- Rafflesia, with the world's largest flower, has evolved to produce a "corpse" smell to attract insects.
- Duckweed is an invasive species from Asia, with the world's smallest fruit.
- Baobab trees in Madagascar have evolved to have large, thick trunks.
- Colocynth lives in North African deserts like Libya.
Evolutionary Relationships of Flowering Plants
- Morphological classifications are known as phenetic classification systems.
- Phenetic classifications emphasize conservative characters that do not vary with environmental conditions.
- The publication of Charles Darwin's Origin of Species (1859) increased interest in the phylogenetic approach to classification, which emphasizes evolutionary relationships.
- In the 19th century two competing theories regarding flowering plant evolution were given:
- ENGLER, Adolf (Germany, 1844-1930): the earliest evolved flowers were small, structurally simple, and wind-pollinated
- HOOKER, Joseph D.(England, 1817-1911): The earliest evolved flowers were large with numerous floral parts.
- The Hooker system is accepted today; between 300 and 350 flowering plant families are recognized.
- Molecular biology studies of plant genomes have largely confirmed the evolutionary validity of the Hooker-Bessey-Cronquist system, although many refinements have been made.
Flowering Plants: Monocots and Eudicots
- Traditional plant classification recognizes two major flowering plant groups: the monocotyledons (or monocots) and the eudicotyledons (or eudicots).
- This division is based on the number of cotyledons ("seed leaves") found in the seed: monocots have a single cotyledon, whereas eudicots have two cotyledons.
- Several additional morphological features distinguish these two groups (although there are exceptions):
-
Monocots:
- Plant Form: Herbaceous, never woody (some are "tree-like")
- Floral Parts: Three or multiples [3,6,9..]
- Leaves: Linear, sheathing the base, parallel-veined.
- Root System: Primary root is short-lived, fibrous root system developed.
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Eudicots:
- Herbaceous or woody ("true" trees and shrubs).
- Four, five or multiples [4,8,10..]
- Broad, not sheathing, net veined.
- Primary root often persists, forming a taproot.
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Monocots:
- Recent genetic investigations have revealed that the division of the flowering plants into monocot and eudicot groups is too simplistic.
- A third group, known as the magnoliid Angiosperms, evolved prior to the divergence of the monocots and eudicots.
Early History of Plants and People
- Domestication of plants began approximately 10,000 years ago.
- Prior to domestication, humans lived as nomadic hunter-gatherers.
- Hunter-gatherer populations remained below the environment's carrying capacity.
- Hunter-gatherer societies relied on seasonal food supplies, leading to a nomadic lifestyle.
- Humans are omnivores, and plants played critical roles in early societies, providing food, medicine, and psychoactive substances.
- Hunter-gatherers possessed extensive knowledge of plant life cycles, habitat requirements, and edible parts.
- Present-day !Kung people of central Africa provide insights into hunter-gatherer societies.
- The transition from hunter-gatherer existence to agriculture offers incentives:
- Reliable and plentiful local food supply.
- Access to trade routes.
- Year-round access to water.
- Settlement leads to plant cultivation and animal domestication, resulting in:
- More reliable and stable food supplies.
- Larger human populations.
- Increased control over the environment.
- Sedentary existence with permanent settlements.
- Greater efficiency in food production, leading to more free time and specialization.
Origins of Agriculture
- Agriculture involves land tilling for deliberate crop planting.
- Agriculture emerged from plant domestication and, often, animal domestication.
- The transition from hunter-gatherer to agricultural societies occurred gradually.
- Archeological evidence suggests independent development of agriculture in three regions: Asia Minor, China-Southeast Asia, and the Americas.
- Agriculture became prevalent around 5,000 to 7,000 years ago.
- The earliest evidence of agriculture stems from arid regions, particularly the Fertile Crescent of Asia Minor.
- Factors contributing to agriculture's development in the Fertile Crescent:
- The need for a reliable and adequate food supply in a relatively dry region.
- The presence of wild precursor food plants, especially cereal crops, conducive to domestication.
Domestication of Plants
- Theories explaining the shift from hunter-gatherer to agricultural dependence:
- Childe's Neolithic Revolution (1928): Humans and herd animals congregated during dry periods, influencing soil and vegetation, favoring the growth of "weedy" grasses, precursors to domesticated cereal crops.
- Sauer's Favorable Habitats (1952): Sedentary human populations developed in regions with mild climate, edible plants, good fishing, and adequate water supply.
- Sophisticated agricultural practices emerged around 2500 years ago:
- Aztec (Mexico): Intensive irrigation agriculture.
- Mayan (Central America): Selective breeding of corn and beans.
- Inca (Andes, South America): Potato domestication and irrigation systems.
Selection Pressures on Plants
- Plant characteristics are influenced by their genomes, which evolve through natural selection.
- Plant cultivation significantly alters the phenotypic characteristics of wild plants.
- The "planting-harvesting link" led to passive selection of beneficial cultivars.
- Wild plants often produce numerous seeds, maturing over extended periods to ensure environmental resilience.
- Selection pressures favor specific characteristics in cereal crops:
- Uniform seed maturation.
- Compression of tillering, reducing staggered seed maturation.
- Loss of seed appendages that detach before harvest.
- Loss of germination inhibitors, enabling simultaneous germination.
- Increase in the number of florets, resulting in more seeds.
- Reduced day-length sensitivity to facilitate cultivation in different regions.
- Loss of shattering, ensuring seeds stay on the plant for harvesting.
- Increase in food reserves (starch) within the seed, enhancing seedling growth and competition.
- Selection can also affect weed species:
- Some weeds mature before harvest, maintaining their populations.
- Some weeds mimic crop plants, producing seeds with similar size and maturation times, contaminating harvests.
Geographic Origin and Spread of Plants
- Most common food plants have restricted native geographical ranges.
- The introduction of new crops had significant impacts on agriculture and diets.
- Examples include:
- Potatoes from South America to Europe.
- Tomatoes and chili peppers from South America to Europe and Asia.
- Sugar cane from southeast Asia to the Caribbean.
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Europe:
- Romans introduced Mediterranean species like peas, oats, rye, and herbs into northern Europe.
- Arabic colonization of Spain brought in rice, sugarcane, sorghum, and citrus fruits.
- European conquest of the Americas introduced corn and potatoes to Europe.
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Asia:
- Asia has diverse indigenous food plants, notably rice.
- Many cereals, cucurbits, and brassicas exhibit high mutability.
Genetic Engineering
- Genetic engineering involves adding genetic information from other organisms into crop plants.
- GE crops have become more prevalent in recent years, with uses including pest, pathogen, and herbicide resistance.
- Consumer resistance to GE crops is strong in Europe, leading to bans or strict regulations.
- Concerns regarding GE crops:
- Potential escape into natural habitats and hybridization with native plants.
- Concerns about the safety and health of GE crops.
- Higher cost of GE seeds, limiting access for farmers in developing nations.
Genetic Diversity
- The development of new crop varieties, crops, and medicinal drugs relies on genetic diversity.
- The disappearance of older, less productive plant varieties poses concerns, as they may hold valuable genetic information for future breeding programs.
- The loss of tropical rainforests and other natural ecosystems is a significant issue, as they represent a vast reservoir of genetic resources.
- It is estimated that rainforests contain nearly three-quarters of all species on Earth.
Cereal Crops
- Cereal crops, like wheat, rice, and corn, were essential to the development of agriculture.
- Cereal grain is a concentrated food source, rich in carbohydrates with some protein, oil, vitamins, and minerals.
- Cereals can be stored for long periods due to their low water content.
- Cereal grains are fruits belonging to the Grass family (Poaceae).
- Grasses produce a dry indehiscent fruit called a caryopsis.
- The caryopsis is mostly seed, with a hard pericarp fused to the seed coat.
Bread Wheat (Triticum aestivum)
- Bread wheat originated in Asia Minor (present-day Iraq) through a series of hybridization events involving three genera: Triticum, Agropyron, and Aegilops.
- The final hexaploid bread wheat has 42 chromosomes (six times the base chromosome number, N=7).
- Archaeological evidence suggests wheat cultivation in Jarmo (present-day Iraq) around 9,000 years ago.
- Ancient grains, such as einkorn wheat (diploid) and emmer wheat (tetraploid), were first cultivated in Asia Minor around 8,000 years ago.
- There are two main types of wheat: hexaploid bread wheat (T. aestivum) and tetraploid durum wheat (T. durum).
- Bread wheat varieties are categorized into spring and winter types, depending on their planting season.
- Spring wheat has a 90-day growing season and is common in cool temperate regions.
- Winter wheat is sown in fall, germinates in late fall, overwinters as seedlings, and is harvested in mid-summer.
- Winter wheat requires moist fall weather, a mild winter, and adequate snow cover.
- Black stem rust fungus is a significant pathogen for wheat, and breeding programs focus on enhancing resistance.
- Black stem fungus attacks the endosperm, reducing yield.
Wheat Grain Structure
- A wheat grain consists of three parts:
- Germ: plant embryo, rich in oils and protein.
- Bran: outer coating, includes seed coat, aleurone layer, and husk, containing protein, enzymes, and fiber.
- White flour (semolina): endosperm tissue, primarily starch, the food source for the developing embryo.
- The germ makes up about 6% of the grain, the bran about 4%, and the white flour about 85-90%.
Wheat Processing (Milling)
- Wheat grain processing involves:
- Cleaning: removes glumes and other inedible parts.
- Tempering: moistening grain to toughen the bran and prevent fragmentation.
- Crushing: removes the bran and germ.
- Separating: produces white flour (endosperm) and bran and germ (used for animal feed).
- Wheat is unique among cereal grains because it contains both gliadin and glutenin proteins necessary for bread-making.
- During baking, yeasts ferment sugars in the dough, releasing carbon dioxide (CO2) trapped by gluten, causing the dough to rise.
Corn or Maize (Zea mays)
- Corn (maize in Europe) is native to Central America and has been cultivated for at least 7,000 years.
- Corn was critical to the Mayan, Aztec, and Inca civilizations.
- Modern corn is a mutated derivative of the wild grass teosinte.
- Corn is unique because its male (tassels) and female (ears) flowers are separated.
- Corn is low in protein (especially lysine) and some vitamins compared to other cereal grains.
- Corn lacks gluten proteins, limiting its use for bread-making.
- Corn is widely grown in Central and North America for livestock feed, human consumption, and bioethanol production.
- Hybrid vigor in corn cultivars is maintained by crossing inbred lines.
- Hybrids are stronger and healthier than true breeds, and this is achieved more easily in corn due to its separate male and female flowers.
- Traditional hybrid vigor was maintained using double-crossing, but this process is time-consuming.
- In the 1960s, a male-sterile line was developed, which inadvertently carried a susceptibility to southern corn blight, leading to a devastating crop failure in 1970.
- Recent molecular genetics research indicates that corn is a mutated derivative of the wild grass teosinte.
Rice
- Archaeological evidence suggests early rice cultivation in China and Southeast Asia.
- Rice requires a hot, humid climate with high rainfall.
- Most commercial varieties (paddy rice) need continuous submergence in water for 2-3 months.
- Upland rice is grown in high-rainfall areas with saturated soils and does not need submergence.
- Rice demands nutrient-rich soil, especially nitrogen, and is labor-intensive.
- Rice cultivars are categorized into two major groups: long-grained (indica) and short-grained (sativa).
- Hybridization programs have significantly boosted rice crop yields.
- Rice is typically consumed with minimal processing.
- Rice processing involves:
- Threshing: separates grains from chaff.
- Pearling and Polishing: removes bran and germ, resulting in white rice, but also significant nutrient loss.
Polished White Rice
- Polished white rice grains are predominantly starch (about 92%), low in protein, and lack gluten proteins.
- Polishing removes thiamine (vitamin B1), leading to thiamine deficiency and the potential for beriberi disease.
Beriberi Disease
- Beriberi symptoms include weight loss, reduced sensory perception, limb pain and weakness, and emotional disturbances.
- Beriberi became a health issue in parts of Asia in the early 1900s when polished white rice replaced traditional brown rice.
Other Cereal Crops
Oats (Avena sativa)
- Oats are important as forage and fodder for cattle.
- Oats contain a high protein content, the highest of all cereals, but lack gluten proteins.
Rye (Secale cereale)
- Rye likely originated from S. montanum, a weed mimicking wheat and barley crops.
- Rye thrives in cool climates and tolerates nutrient-poor soils.
- Rye is mainly grown for fodder and pasture, but is also used for bread flour, especially in Eastern Europe and Russia.
- Due to its low gluten content, rye flour produces dense, dark, and bitter bread.
Fungal Ergot
- Rye can be infected with fungal ergot in wet seasons, causing severe symptoms like convulsions, paralysis, gangrene, and hallucinations in humans.
- Symptoms of ergot poisoning, including convulsions, paralysis, gangrene, and hallucinations, have been linked to historical events, including witch trials, demonic possessions, and religious visions.
- Ergot contains ergotamine, LSD, and alkaloid compounds with dangerous physiological effects in humans.
Ergot Contamination
- The FDA allows acceptable levels of ergot contamination in crops.
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This quiz explores the botanical characteristics and historical significance of Eragrostis tef, a key food plant from Ethiopia. Learn about its cultivation, processing, and traditional uses in Ethiopian cuisine, particularly in making injera and other staple foods.
