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Botanically, a seed is defined as a plant structure comprising an embryo and stored nutrients, enveloped by a protective testa, and originating from a fertilized ovule.
Answer: True
The botanical definition specifies a seed as a structure containing an embryo and nutrients, enclosed by a protective testa, and developing from a fertilized ovule.
In a broader, non-botanical context, the term 'seed' may encompass any plant propagation unit capable of being sown, such as tubers or bulbs.
Answer: True
The term 'seed' is sometimes used more broadly to include any structure that can be sown for propagation, even if it does not meet the strict botanical definition of a seed.
In flowering plants, the fruit develops from the ovary post-fertilization, typically serving to protect and facilitate the dissemination of the seed.
Answer: True
Following fertilization in angiosperms, the ovary matures into a fruit, which generally functions to protect the seed and aid in its dispersal.
All items commonly referred to as 'seeds,' such as sunflower seeds and nuts, are botanically classified as true seeds.
Answer: False
Many items commonly called 'seeds,' including sunflower seeds and nuts, are botanically classified as fruits, not true seeds.
The micropyle is a primary component of a plant ovule, serving as the main body where the megagametophyte develops.
Answer: False
The micropyle is a small pore in the ovule, typically serving as the entry point for the pollen tube. The nucellus is the main body of the ovule where the megagametophyte develops.
The shape of the ovule during its development does not influence the final shape of the seed.
Answer: False
The morphology of the ovule during its development directly influences the final shape of the seed. Various ovule orientations and curvatures lead to diverse seed shapes.
The radicle represents the embryonic root tip, and the plumule signifies the embryonic shoot tip, both constituting principal components of a plant embryo.
Answer: True
The radicle is indeed the embryonic root, and the plumule is the embryonic shoot. These are fundamental parts of the plant embryo within a seed.
Monocotyledonous plants possess unique structures known as the coleoptile and coleorhiza, which protect the developing shoot and embryonic root, respectively.
Answer: True
In monocots, the coleoptile is a protective sheath for the plumule (shoot), and the coleorhiza is a protective sheath for the radicle (root).
The seed coat develops from the embryo itself, with the testa forming from the inner integument and the tegmen from the outer integument.
Answer: False
The seed coat develops from the integuments of the ovule, not the embryo. The outer integument typically forms the testa, and the inner integument forms the tegmen.
The seed coat's primary function is to attract pollinators to the seed.
Answer: False
The primary functions of the seed coat are protection of the embryo from mechanical damage, dehydration, and predation, not attracting pollinators.
Seeds can be described as reniform if they are kidney-shaped or globose if they are spherical.
Answer: True
Descriptive terms for seed shape include reniform for kidney-shaped and globose for spherical.
The two fundamental parts of a typical seed are the embryo and the endosperm, with the seed coat being optional.
Answer: False
The two fundamental parts of a typical seed are the embryo and the seed coat. The endosperm is a nutritive tissue present in many seeds but not universally considered a fundamental part in the same way as the embryo and seed coat.
Seed types are classified based on factors like embryo morphology, endosperm amount, and embryo position relative to the endosperm.
Answer: True
Classification of seed types commonly considers embryo morphology, the presence and quantity of endosperm, and the relative positions of these structures within the seed.
Endospermic (albuminous) seeds retain their endosperm at maturity for nourishment, while non-endospermic (exalbuminous) seeds have the endosperm fully absorbed by the embryo.
Answer: True
This distinction accurately describes endospermic seeds, which retain endosperm, and exalbuminous seeds, where the endosperm is absorbed by the developing embryo, often by the cotyledons.
Based on the botanical definition, what are the essential components contained within a seed's protective testa?
Answer: An embryo and stored nutrients
The botanical definition of a seed specifies that it contains an embryo and stored nutrients, enclosed within the protective testa.
Which of the following is NOT considered a true seed in a botanical sense, despite sometimes being referred to as one?
Answer: A sunflower seed
Sunflower 'seeds' are botanically classified as fruits (achenes), where the pericarp (fruit wall) is fused to the seed coat. While pea seeds, wheat grains, and corn kernels are also botanically fruits (caryopses), the source material specifically highlights sunflower seeds as an example of a commonly misidentified 'seed'.
What is the role of the fruit in flowering plants concerning seed reproduction?
Answer: The fruit ripens from the ovary, enclosing and aiding the dissemination of the seed.
In angiosperms, the fruit develops from the ovary and serves to enclose, protect, and facilitate the dispersal of the seed(s) contained within.
Which part of the plant ovule typically serves as the entry point for the pollen tube during fertilization?
Answer: The micropyle
The micropyle is a small opening in the ovule's integuments that typically allows the pollen tube to enter for fertilization.
What are the primary components that constitute a plant embryo within a seed?
Answer: Cotyledons, epicotyl, hypocotyl, plumule, and radicle
A plant embryo typically consists of cotyledons (seed leaves), the epicotyl, hypocotyl, plumule (embryonic shoot), and radicle (embryonic root).
In monocotyledonous plants, what are the protective sheathing structures covering the plumule and radicle called?
Answer: Coleoptile and coleorhiza
Monocots possess a coleoptile that protects the plumule and a coleorhiza that protects the radicle.
The seed coat develops from which part of the ovule?
Answer: The integuments
The seed coat originates from the integuments, which are the outer layers of the ovule.
Which of the following is a primary protective function of the seed coat?
Answer: Protecting the embryo from mechanical damage and dehydration
The seed coat's principal role is to safeguard the embryo against physical injury and desiccation.
A seed described as 'reniform' would have which shape?
Answer: Kidney-shaped
The term 'reniform' is used in botanical descriptions to denote a kidney-shaped morphology.
What are the two fundamental parts of a typical seed, according to the source?
Answer: Embryo and seed coat
The two fundamental components of a typical seed are the embryo and the seed coat.
Seeds that retain their endosperm at maturity for nourishment are classified as:
Answer: Both B and C
Seeds that retain their endosperm at maturity are referred to as both albuminous and endospermic.
Ferns and mosses reproduce via seeds, analogous to the reproductive strategy of seed plants (spermatophytes).
Answer: False
This statement is incorrect. Ferns and mosses reproduce using spores, not seeds. Seed production is a defining characteristic of spermatophytes.
The earliest land plants, which emerged approximately 468 million years ago, reproduced using seeds.
Answer: False
The earliest land plants, emerging around 468 million years ago, reproduced via spores. Seed reproduction evolved later.
Gymnosperms, appearing in the late Devonian period, were the earliest seed-bearing plants and produced seeds enclosed within an ovary.
Answer: False
Gymnosperms were indeed the earliest seed-bearing plants, appearing in the late Devonian period. However, their seeds were not enclosed within an ovary; this characteristic defines angiosperms.
Seed ferns, which evolved during the Carboniferous period, bore their ovules within a cupule, a structure likely formed from protective branches.
Answer: True
Seed ferns, prominent during the Carboniferous period, are characterized by bearing their ovules within a cupule, a structure believed to be derived from modified branches offering protection.
The defining characteristic of reproduction in seed plants (spermatophytes) is the formation of a seed.
Answer: True
The capacity to produce seeds, which encapsulate the embryo and nutritive tissue, is the fundamental reproductive innovation that defines seed plants (spermatophytes).
Double fertilization in angiosperms involves the fusion of one male gamete with the egg cell, leading to the embryo, and the other male gamete with the central cell, forming the endosperm.
Answer: True
Double fertilization is a unique process in angiosperms where one male gamete fertilizes the egg to form the zygote (embryo), and a second male gamete fuses with the central cell to form the triploid endosperm, a nutritive tissue.
The earliest 'true' seeds, found in the fossil record, date back to the Carboniferous period.
Answer: False
The earliest 'true' seeds are documented in the fossil record from the Late Devonian period, predating the Carboniferous period.
How do seed plants (spermatophytes) fundamentally differ in reproduction from plants like ferns and mosses?
Answer: Seed plants reproduce using seeds, whereas ferns and mosses do not.
The principal reproductive divergence is that seed plants (spermatophytes) produce seeds, a characteristic absent in ferns and mosses, which reproduce via spores.
Which geological period saw the emergence of the earliest seed-bearing plants, known as gymnosperms?
Answer: The Late Devonian period
Gymnosperms, the earliest seed-bearing plants, first appeared during the Late Devonian period.
Seed ferns, which evolved during the Carboniferous period, are noted for bearing their ovules in what structure?
Answer: A cupule
Seed ferns of the Carboniferous period bore their ovules within a structure known as a cupule, which likely provided protection.
The process of double fertilization in angiosperms results in the formation of:
Answer: The zygote (embryo) and the primary endosperm
Double fertilization in angiosperms yields the zygote, which develops into the embryo, and the primary endosperm nucleus, which develops into the endosperm.
The earliest 'true' seeds found in the fossil record date back to which period?
Answer: The Late Devonian period
Fossil evidence indicates that the earliest 'true' seeds originated during the Late Devonian period.
Seed dispersal mechanisms include anemochory (wind), hydrochory (water), and zoochory (animals), but not myrmecochory (ants).
Answer: False
Myrmecochory, the dispersal of seeds by ants, is a recognized mechanism of seed dispersal, alongside anemochory, hydrochory, and zoochory.
Seeds adapted for wind dispersal often possess wings, lightweight structures, or hairs to aid in aerial transport.
Answer: True
Adaptations such as wings, pappi (hairs), or reduced seed mass are common in seeds evolved for efficient dispersal by wind currents.
Animals facilitate seed dispersal by carrying seeds attached to fur, consuming fruits and excreting seeds, or burying seeds for later consumption.
Answer: True
Zoochory, or animal-mediated seed dispersal, occurs through various means including external transport on fur, internal transport via ingestion and defecation, and caching or hoarding behavior.
Myrmecochory refers to seed dispersal by wind, utilizing specialized structures to catch air currents.
Answer: False
Myrmecochory specifically denotes seed dispersal by ants. Wind dispersal is termed anemochory.
What is the term for seed dispersal by animals?
Answer: Zoochory
Seed dispersal mediated by animals is termed zoochory.
Which adaptation is commonly found in seeds designed for dispersal by wind?
Answer: Wings or lightweight, hairy structures
Seeds adapted for anemochory (wind dispersal) often possess structures like wings or hairs that increase their surface area and reduce their density, facilitating aerial transport.
Myrmecochory is a specific type of seed dispersal facilitated by:
Answer: Ants
Myrmecochory refers to the dispersal of seeds by ants, often facilitated by nutrient-rich appendages on the seeds.
Seed dormancy primarily serves to synchronize germination with favorable conditions and to spread germination over time.
Answer: True
Dormancy is a critical adaptive strategy that ensures seeds germinate only when environmental conditions are optimal for seedling survival and allows for temporal dispersal of germination events.
Induced dormancy (enforced dormancy) is caused by internal seed conditions preventing germination, even when environmental conditions are favorable.
Answer: False
Induced dormancy, or enforced dormancy, is caused by unfavorable external environmental conditions that prevent germination, even if the seed's internal state is conducive. True dormancy (innate dormancy) is due to internal seed conditions.
Physical dormancy is characterized by the seed coat being impermeable to water and gases, often requiring disruption of a 'water gap' for germination.
Answer: True
Physical dormancy arises from a seed coat that prevents water and gas exchange. Germination is often triggered by mechanical or environmental disruption of this impermeable layer, sometimes involving a specific 'water gap'.
Chemical dormancy is overcome by the seed coat being physically broken or scratched.
Answer: False
Chemical dormancy is overcome by the leaching or degradation of inhibitory chemical compounds within the seed, not by physical damage to the seed coat, which is characteristic of physical dormancy.
Morphological dormancy implies that the embryo is fully developed at the time of seed dispersal.
Answer: False
Morphological dormancy is characterized by an underdeveloped or undifferentiated embryo at the time of seed dispersal, requiring further development before germination can proceed.
Viability of the embryo, satisfaction of dormancy requirements, and suitable environmental conditions (water, oxygen, temperature, light) are essential for seed germination.
Answer: True
Successful seed germination necessitates a viable embryo, the fulfillment of any dormancy requirements, and the presence of appropriate environmental cues such as water, oxygen, temperature, and sometimes light.
The three phases of seed germination are water imbibition, metabolic reactivation (lag phase), and radicle emergence.
Answer: True
The process of seed germination is typically described in three phases: initial water uptake (imbibition), a period of metabolic activity (lag phase), and the emergence of the radicle.
Scarification is a process used to break physiological dormancy by exposing seeds to cold temperatures.
Answer: False
Scarification involves weakening or breaking the seed coat to facilitate water and gas penetration. Exposure to cold temperatures to break dormancy is known as stratification.
Stratification, or moist-chilling, is used to break physiological dormancy by keeping seeds moist and cold for a period.
Answer: True
Stratification, commonly referred to as moist-chilling, is a technique employed to overcome physiological dormancy by subjecting seeds to specific periods of cold, moist conditions.
What is the primary benefit of seed dormancy for a plant species?
Answer: To prevent germination until environmental conditions are optimal
Seed dormancy is a crucial adaptation that prevents germination under suboptimal or unfavorable environmental conditions, thereby increasing the likelihood of seedling survival.
Which type of seed dormancy is caused by external environmental conditions being unsuitable for germination?
Answer: Induced dormancy
Induced dormancy, also known as enforced dormancy, occurs when external environmental factors inhibit germination, rather than internal seed characteristics.
Physical dormancy in seeds is primarily due to:
Answer: The seed coat being impermeable to water and gases
Physical dormancy is characterized by a seed coat that prevents the necessary uptake of water and gases, thereby inhibiting germination.
What is scarification, and why is it performed on some seeds?
Answer: Weakening or breaking the seed coat; performed to allow water/gas penetration.
Scarification is the process of weakening or breaching the seed coat, typically to facilitate the entry of water and gases, thereby overcoming physical dormancy.
Stratification is a process used to break dormancy by:
Answer: Keeping seeds moist and exposed to cold temperatures
Stratification involves maintaining seeds in moist, cold conditions for a specific duration to break dormancy, particularly physiological dormancy.
Seed vigor refers to the percentage of seeds that are non-viable.
Answer: False
Seed vigor pertains to the quality of seeds, encompassing their viability, germination rate, and the strength of the resulting seedlings, not the percentage of non-viable seeds.
DNA repair mechanisms, such as those involving ligase, are important for maintaining seed longevity by counteracting accumulated damage during dormancy.
Answer: True
The ability of seeds to repair accumulated DNA damage during dormancy, utilizing enzymes like ligase, is considered crucial for preserving viability and ensuring longevity.
The seed microbiome refers to the microorganisms found within the seed, which can influence plant health.
Answer: True
The seed microbiome comprises the microbial communities residing within seeds, and these microbes can exert significant influence on the health and development of the resulting plant.
What is the significance of the seed microbiome?
Answer: It is a community of microorganisms within the seed that can affect plant health.
The seed microbiome consists of microorganisms residing within the seed, which can play roles in plant health and development.
Seeds primarily serve the parent plant by storing water and providing structural support.
Answer: False
Seeds primarily serve the embryo by providing nourishment, facilitating dispersal, and enabling dormancy for survival. Their role is for the offspring, not directly for the parent plant's structural support or water storage.
Seeds provide nourishment to the embryo through stored food reserves in the endosperm or cotyledons, allowing for a faster start than sporelings.
Answer: True
The stored food reserves within seeds, located in the endosperm or cotyledons, are crucial for nourishing the developing embryo, providing a significant advantage over spore-based reproduction.
U.S. farmers spent approximately $22 billion on seeds in 2018, a decrease from 2010 spending.
Answer: False
U.S. farmers spent approximately $22 billion on seeds in 2018, which represented a 35 percent increase compared to 2010 spending.
The primary sources of human calories derived from seeds are nuts and vegetables.
Answer: False
The principal sources of human caloric intake from seeds are staple crops such as cereals and legumes, in addition to nuts.
Many legume seeds are unsafe to eat raw due to compounds like lectins and trypsin inhibitors, which are denatured by cooking.
Answer: True
Raw legume seeds often contain antinutritional factors, such as lectins and trypsin inhibitors, which can cause adverse health effects and are deactivated by cooking processes that denature these compounds.
Ricin is a non-toxic substance found in the seeds of the castor bean plant.
Answer: False
Ricin is a highly toxic protein derived from the seeds of the castor bean plant (*Ricinus communis*).
Seeds from apples and cherries can potentially cause cyanide poisoning if consumed in large quantities due to the presence of amygdalin.
Answer: True
The seeds of certain fruits, including apples and cherries, contain amygdalin, which can metabolize into cyanide and pose a risk of poisoning if ingested in significant amounts.
Besides food, seeds are used for extracting industrial oils, providing fibers like cotton, and as decorative items.
Answer: True
Seeds have diverse applications beyond nutrition, including the extraction of industrial oils and the production of fibers such as cotton.
The coco de mer palm produces the largest known seed, with its fruit potentially weighing up to 23 kilograms.
Answer: True
The coco de mer palm (*Lodoicea maldivica*) is recognized for producing the world's largest seed, with its characteristic fruit capable of reaching weights of up to 23 kilograms.
The oldest viable seed known to have germinated was a sunflower seed recovered from ancient Egyptian tombs.
Answer: False
The oldest known viable seed to germinate was a Judean date palm seed, estimated to be approximately 2,000 years old, recovered from archaeological excavations in Israel.
Which of the following is NOT one of the three main functions seeds perform for the parent plant?
Answer: Absorbing atmospheric carbon dioxide
The primary functions of seeds are to nourish the embryo, facilitate dispersal, and enable dormancy. Absorbing atmospheric carbon dioxide is a function of the parent plant's photosynthetic tissues.
How do seeds primarily contribute to the survival and development of the embryo?
Answer: By storing food reserves in the endosperm or cotyledons
Seeds ensure embryo survival and development primarily by providing stored food reserves within the endosperm or cotyledons.
In 2018, U.S. farmers spent approximately how much on seeds, representing an increase from 2010?
Answer: $22 billion
In 2018, U.S. farmers' expenditure on seeds reached approximately $22 billion, indicating an increase from 2010 levels.
Which of the following are the primary sources of calories derived from seeds for human consumption?
Answer: Cereals, legumes, and nuts
The majority of human caloric intake derived from seeds comes from staple crops such as cereals and legumes, along with nuts.
Why are many raw legume seeds considered unsafe to eat?
Answer: They contain compounds like lectins and trypsin inhibitors.
Many raw legume seeds contain antinutritional compounds, such as lectins and trypsin inhibitors, which can cause adverse health effects and are deactivated by cooking.
Ricin, a potent toxin, is derived from the seeds of which plant?
Answer: Castor bean (*Ricinus communis*)
Ricin is a highly toxic substance extracted from the seeds of the castor bean plant (*Ricinus communis*).
Which of these seeds can potentially lead to cyanide poisoning if consumed in significant quantities?
Answer: Apple seeds
Seeds from fruits like apples, cherries, and apricots contain amygdalin, which can release cyanide and cause poisoning if consumed in large amounts.
Besides being a food source, seeds are utilized for:
Answer: Extracting industrial oils and providing fibers
Seeds serve multiple purposes beyond food, including the extraction of industrial oils and the provision of fibers like cotton.
What plant is known to produce the largest seed in the world, with its fruit weighing up to 23 kg?
Answer: Coco de mer palm
The coco de mer palm (*Lodoicea maldivica*) produces the largest known seed, with its fruit potentially weighing up to 23 kilograms.
What is the oldest known viable seed that has successfully germinated and grown into a plant?
Answer: A Judean date palm seed (~2,000 years old)
The oldest successfully germinated viable seed is a Judean date palm seed, estimated to be around 2,000 years old.
The Book of Genesis describes the creation of seed-bearing plants on the second day of creation.
Answer: False
According to the Book of Genesis, seed-bearing plants were created on the third day of creation.
The Quran describes Allah as the one who causes seed-grains and date-stones to split and sprout, bringing forth life.
Answer: True
The Quran attributes the process of splitting seed-grains and date-stones and bringing forth life from them to Allah.
According to the Book of Genesis, on which day were seed-bearing plants created?
Answer: The third day
The Book of Genesis states that seed-bearing plants were created on the third day of creation.