Answer:
C. George Cuvier
Explanation:
During the 19th century, Georges Cuvier developed his own theory of catastrophes. Fossils show that animal and plant species are destroyed time and again by floods and other natural disasters, and that new species evolve shortly after that.
the layer of the skin called the lacks blood vessels.
The epidermis layer of the skin called the lacks blood vessels.
The skin has three layers: The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
The dermis, beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
The epidermis is visible to the eye and works to provide protection to the body. It does not contain any blood vessels and is, therefore, dependent on the dermis, the layer of the skin underneath it, to provide access to nutrients and dispose of waste. Hence, the epidermis is the layer of skin that does not contain blood vessels.
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what ingredients are broken down by enzymes during the modification of barley?
Through the activity of enzymes released from the aleurone layer and perhaps the scutellum during germination, modification refers to the disintegration of cell walls and the conversion of starch to sugars in the endosperm of grains.
The modification of barley is also known as Malting. Malting is a test of practical biochemistry, particularly enzymology. Both the carbohydrate, protein, and nucleic acid molecules stored in barley grains and the fermentation processes carried out by brewing yeasts are not supported by these molecules. Before the yeast can utilize these big and physically complicated molecules, they must first partially or, in some cases, completely breakdown into their constituent sugars, amino acids, and nucleotides. When barley seeds sprout, hydrolytic enzymes are created or transformed into active forms that can quickly break down these heavy substances.
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what is an environmental agent that significantly increases the rate of mutation above the spontaneous rate called? tautomer mutagen transposon missense agent ames agent
An environmental agent that significantly increases the rate of mutation above the spontaneous rate is called mutagen.
A mutagen is a substance that can cause DNA mutations by chemical or physical means. Tobacco products, radioactive compounds, x-rays, ultraviolet radiation, and a wide range of chemicals are a few examples of mutagens. DNA mutations that cause or support the development of some diseases can result from exposure to a mutagen.
The following are the impacts of mutagens: DNA is altered by mutagens, which can result in issues with transcription, replication, and, in severe situations, cell death. Chromosome breakages and rearrangements including translocation, deletion, and inversion can be brought on by strong mutagens that produce chromosomal instability. Certain mutagens can result in aneuploidy, which is a change in the number of chromosomes in a cell.
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Which layer of the skin is composed of stratified squamous epithelium?
The epidermis, which is the outermost layer of the skin, is composed of stratified squamous epithelium.
This layer is primarily responsible for providing a barrier between the external environment and the underlying tissues, and it is also involved in the production of melanin, which helps protect the skin from UV radiation. The epidermis is constantly shedding dead skin cells and producing new ones, which allows for the maintenance and repair of the skin. Beneath the epidermis is the dermis, which contains connective tissue, blood vessels, and nerve endings, among other structures. The epidermis also contains melanocytes, which are responsible for producing the pigment melanin that gives the skin its color and helps protect it from radiation. Additionally, the epidermis contains Langerhans cells, which are a type of immune cell that helps protect against infection and cancer.
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What makes membrane potential more positive?
The membrane potential normally becomes more positive in response to neurotransmitters that open Na+ channels.
Whereas the membrane potential typically becomes more negatively responsive to neurotransmitters that open K+ channels.
The voltage known as the membrane potential is caused by variations in the concentrations of ions on the opposing sides of a cellular membrane. The typical membrane potential ranges from -70 mV to -40 mV. Potassium (K+), which has a high concentration inside the membrane and a low concentration outside, is one of the ions that have a concentration gradient across it. In the extracellular and intracellular regions, respectively, sodium (Na+) and chloride (Cl) ions are present in high and low amounts.
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Summarize the phases of cellular respiration.
All of the following statements about respiration in birds and mammals are correct except _____. (a) A single breath of air remains in a mammal's respiratory system for one inhale and one exhale and in a bird's respiratory system for three cycles of inhalation and exhalation. (b) Air sacs are present in the respiratory systems of birds but not mammals. (c) Because of the efficiency of their respiratory systems, we would expect to see birds, but not mammals, at very high altitudes. (d) Mammals have more dead space but also greater surface area of exchange in their respiratory exchange organ than do birds. (e) Ventilation in bird lungs is unidirectional, but ventilation in mammal lungs is tidal.
The ideal decision is (d). In their respiratory exchange organ, mammals have a larger surface area for exchange than do birds, but they also have more dead space.
They have developed diverse ideal respiratory structures in response to restrictions and limitations brought on by phylogeny, behaviour, body size, and environment. Gas exchangers are the epitome of the proverb "necessity is the mother of invention," as they were developed through rigorous cost-benefit assessments that required trade-offs and compromises. Constructions of gas exchangers show strong structural-functional relationships: within and between taxa, morphological complexity and respiratory efficiency rise with metabolic capacity and oxygen requirements. Small, highly active endotherms have more refined gas exchangers than huge, inactive ectotherms.
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If an increase in global temperatures causes parts of Alaska to remain snow free for two additional weeks each year, what affects might that have on earth? Describe 2-3 effects that may be seen on earth
There will be a decrease in the planet's albedo or reflectivity if interior Alaska remains snow-free.
What is albedo?
TThe ratio of a surface's radiosity (J) to its irradiance (Ee) (flux per unit area) is known as its albedo. The amount of solar radiation that reaches the Earth's surface and its spectral and angular distribution both influence how much of it is reflected. These variables change depending on the type of atmosphere, the location, and the time (see position of the Sun). Albedo is the directional integration of reflectance over all solar angles in a given period, as opposed to bi-hemispherical reflectance, which is calculated for a single angle of incidence (i.e., for a given position of the Sun). The temporal resolution can be measured in seconds (as determined by flux measurements) or as averages of a day, a month, or an entire year.To know more about albedo, click the link given below:
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how do the layers of the cortex differ from each other? group of answer choices they contain different types and sizes of cells. they form different structures. some of the layers contain neurons, while others contain glial cells. some of the layers contain columns, while others do not.
Option C, The layers of the cortex differ from each other in that they contain different types and sizes of cells.
The cortex is the outer layer of the brain that plays a critical role in many functions, including perception, cognition, and movement. The cortex is organized into six distinct layers, each of which contains different types of cells and connections. The cells in the different layers of the cortex vary in their size, shape, and function. For example, layer 4 of the cortex contains dense clusters of neurons called "granule cells," which are important for relaying sensory information, while layer 5 contains large, pyramidal neurons that send information to other parts of the brain and spinal cord. The layers of the cortex also differ in the patterns of their connections, with some layers containing more connections within the cortex and others containing more connections to other brain regions. Overall, the distinct layers of the cortex are important for the complex functions of the brain, and their differences contribute to the overall complexity and specialization of the brain's architecture.
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The complete Question is:
How do the layers of the cortex differ from each other?
A. They form different structures
B. Some of the layers contain columns, while others do not
C. They contain different types and sizes of cells
D. Some of the layers contain neurons, while others contain glial cells.
what happens to the products of digestion after absorption?
The products of digestion after absorption is passed by the circulatory system to other parts of your body to store or for different types of uses.
What is Digestion?This is referred to as the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma.
The circulatory system which comprises of the blood etc passes them on to other parts of your body to store or use through the help of special cells help absorbed nutrients cross the intestinal lining into your bloodstream.
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the world's agricultural hearth areas are those regions where plants and animals were domesticated where swidden cultivation is practiced. where an agricultural surplus is produced. from where the core gets most of its food.
Some examples of agricultural hearth areas include the Fertile Crescent, Mesoamerica, and the Andean highlands.
Swidden cultivation, also known as slash-and-burn agriculture, is a traditional method of clearing land for farming by cutting and burning vegetation. Agricultural surplus refers to the amount of food that is produced beyond what is needed for subsistence, which allows for trade and development of complex societies.Certainly! In addition to the Fertile Crescent, Mesoamerica, and the Andean highlands, other agricultural hearth areas include the Yellow River Valley in China and the Nile River Valley in Egypt. These regions are considered to be the birthplaces of agriculture because they were some of the first places in the world where people domesticated plants and animals for food production.
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What is the structure of the vesicle membrane?
The structure of the vesicle membrane is composed of a lipid bilayer, which is composed of two layers of phospholipid molecules. The head of each phospholipid molecule is hydrophilic (water-loving) and the tail is hydrophobic (water-fearing). The hydrophobic tails face each other in the center of the bilayer, forming a barrier that separates the interior of the vesicle from the outside environment. The hydrophilic heads face outward, making contact with the water-based environment inside and outside the vesicle. This lipid bilayer structure allows the vesicle to maintain its shape and separate its contents from the surrounding environment. Additionally, certain proteins can be embedded within the lipid bilayer, serving various functions such as the transport of molecules in and out of the vesicle.
Answer:
The vesicle membrane is composed of a phospholipid bilayer, which is a double layer of phospholipid molecules. The phospholipids are arranged in a "head-to-tail" fashion, with the hydrophilic (water-loving) heads facing outward and the hydrophobic (water-fearing) tails facing inward. The membrane also contains proteins, cholesterol, and other molecules that help to regulate the movement of substances in and out of the vesicle.
Explanation:
many proteins in the cytosol are ________ that accelerate metabolic reactions.
The cytosol contains several proteins that work as enzymes to quicken metabolic processes.
The chemical reactions, or metabolism, of our bodies are sped up by proteins known as enzymes. Although certain chemicals are broken down, others are generated. Enzymes (and other catalysts) function by reducing the activation energy and thereby increasing the rate of reaction. The increasing pace occurs in both the forward and reverse directions at the same rate because both directions must pass through the same transition stage. By affixing to their substrates to form enzyme-substrate complexes, enzymes catalyse chemical processes (ES). The substrate binds to the enzyme at a specific location called the active site. While the substrate is still affixed to the active site, the product of the reaction is created and subsequently released from the enzyme.
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why do some species employ both mitosis and meiosis, whereas other species use only mitosis? see concept 13.2 (page) view available hint(s)for part a why do some species employ both mitosis and meiosis, whereas other species use only mitosis? see concept 13.2 (page) they need both if they are producing plant gametes. a single-celled organism only needs mitosis. they need meiosis if the cells are producing organs such as ovaries. they need only meiosis if they produce egg cells. they need only mitosis to make large numbers of cells such as sperm.
Some species use both mitosis and meiosis, others only use mitosis since they must use both to produce animal gametes.
Animals divide their sex and non-sex cells through meiosis, while plants divide their sex and non-sex cells through both mitosis and meiosis. The non-sex cells, such as skin, muscle, and blood cells, are divided through mitosis in humans and all other animal species. This is the case because these cells need to be retrieved quickly because they decrease quickly. Sex cells, including male and female gametes, are haploid and divide via meiosis. Cell division during mitosis and meiosis are both necessary for gamete production in plants. If they are to produce plant (or animal) gametes, they must have both sides.
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the primary consequence of hypercarotenemia is multiple choice question. yellowing of the skin. softening of the bones. poor muscular coordination. night blindness.
The primary consequence of hypercarotenemia is yellowing of the skin.
What is hypercarotenemia?Hypercarotenemia is a condition where there is an excess of carotenoids, which are plant pigments that give fruits and vegetables their yellow, orange, and red color, in the body. This excess can lead to yellowing of the skin, especially in the palms of the hands and soles of the feet.
Carotenoids build up in the stratum corneum of the epidermis and plasma carotenoid levels rise in hypercarotenemia, which causes the skin to appear yellowish.
However, hypercarotenemia is usually not harmful and is generally a cosmetic issue. In severe cases, it can lead to other symptoms, but those are not the primary consequence.
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Other than the time it was alive, what features of the Pederpes suggests it evolved from the Tulerpeton?
The skeletal structure and anatomy of Pederpes, including the presence of fins and limb bones, suggest that it evolved from Tulerpeton as they share similar adaptations for terrestrial locomotion.
What is Pederpes?
Pederpes is a fossilized species of tetrapod, or four-limbed vertebrate, that lived during the Late Devonian period, about 375 million years ago. It is significant because it is one of the earliest known tetrapods and represents a crucial stage in the evolution of land-dwelling vertebrates from their aquatic ancestors.
Pederpes was a small, amphibian-like animal that had both aquatic and terrestrial adaptations, including fins for swimming and limb bones for crawling on land. The discovery of Pederpes and other early tetrapods provides important insights into the evolution of life on land and the adaptation of vertebrates to different environments.
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why would you expect to find amino acids with nonpolar side chains tucked into the inside of a folded protein?
Amino acids with nonpolar side chains are hydrophobic, meaning they do not interact well with water. Because the interior of a folded protein is generally shielded from the aqueous environment,
It is energetically favorable for hydrophobic amino acids to be tucked into the interior of the protein, where they can avoid contact with water.
Proteins are made up of long chains of amino acids that fold into complex three-dimensional structures. The specific sequence and arrangement of amino acids in a protein determines its shape and function. A protein's shape is critical to its function, and the interior of the protein is often tailored to meet specific functional needs.
Amino acids with nonpolar side chains, such as alanine, leucine, and phenylalanine, are hydrophobic, meaning they do not interact well with water. In contrast, amino acids with polar or charged side chains are hydrophilic and interact well with water. Because water is abundant in cells and is the medium through which many biochemical reactions occur, it is energetically unfavorable for hydrophobic amino acids to be exposed to the aqueous environment.
Therefore, it is common to find hydrophobic amino acids buried in the interior of a folded protein, away from water, and in close proximity to other hydrophobic amino acids. This arrangement reduces the protein's surface area, increases its stability, and enables it to carry out its biological function more effectively.
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Fill in the blank.In the CNS, _____ are cells that line the fluid-filled cavities and which produce, transport, and circulate the fluid surrounding the brain and spinal cord.
Ependymal cells are the cells that line the fluid-filled cavities and create, transport, and circulate the fluid that surrounds the brain and spinal cord in the central nervous system (CNS).
The fluid that covers the brain and spinal cord is created, moved, and circulated by ependymal cells, which line the fluid-filled cavities in the central nervous system (CNS).
The spinal cord and brain are both parts of the central nervous system (CNS). In addition to respiration, heart rate, hormones, and body temperature, it also regulates everything else, including thought, movement, and emotion.
Because it integrates information from every part of the body and organizes movement throughout the entire organism, the CNS is referred to be "central."
A brief description of the CNS is given on this page. The various cell types that are involved, various brain regions, spinal circuitry, and potential impacts of illness and damage on the CNS are all examined.
skin cellular structure Ependymal cells line the cavities of the CNS. Ependymal cells create the cerebrospinal fluid (CSF), and they also act as crucial barriers between the CSF and the extracellular space of the brain.
The choroid plexus epithelial cells create the majority of the CSF that hydrates the ventricles, spinal cord, and subarachnoid spaces.
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which eukaryotic structures are not present in prokaryotic cells?
Answer:
Endoplasmic reticulum, microtubules, and the Golgi apparatus
roth ira contribution limits 2023 married filing jointly
In 2022 and 2023, Roth IRA annual contribution caps are the same as traditional IRA annual contribution caps.
The maximum contribution for tax year 2022 is $6,000 for those under 50 and $7,000 for those over 50. For 2023, you may not contribute more than the following amounts to all of your regular and Roth IRAs: $6,500 ($7,500 if you are 50 or older); or. if less, your taxable income for the entire year.
If you are married and filing jointly, your combined MAGI must be less than $214,000 in 2022 or $228,000 in 2023. A $1,000 catch-up contribution for a total of $7,500 is allowed to be made to a Roth IRA in 2023 if you are 50 years old or older.
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Describe the TWO ways in which CRISPR works in gene editing
Crispr / cas 9 edits genes by precisely cutting dna and then letting natural dna repair processes to take over. The system consists of two parts: the cas 9 enzyme and a guide rna. Rapidly translating a revolutionary technology into transformative therapies.
Answer:
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) works in gene editing through two main mechanisms:
CRISPR-Cas9: This mechanism involves the use of the Cas9 endonuclease enzyme and a guide RNA molecule (gRNA) to find and cut the specific DNA target. The broken DNA is then repaired by the cell's natural processes, resulting in specific mutations or changes in the genetic code.
CRISPR-Cpf1: Similar to CRISPR-Cas9, this mechanism also involves the use of a nuclease enzyme (Cpf1) and a gRNA to target and cut DNA. However, it has some distinct differences from CRISPR-Cas9, such as its ability to target different sites within the genome and create a more stable cut in DNA.
Explanation:
Both of these CRISPR-based mechanisms have the potential to be used for a variety of applications, including the treatment of genetic diseases and the development of new treatments for various medical conditions.
ALLEN
What other types of evidence or features might be used to ascertain whether the tree of life is best represented according to the three-domain or the eocyte hypothesis?
-DNA sequence data
-the fossil record
-cell biology
In addition to DNA sequence data, the fossil record and cell biology are other types of evidence or features that can be used to ascertain whether the tree of life is best represented
according to the three-domain or the eocyte hypothesis.
The fossil record provides physical evidence of past life and can be used to infer the evolutionary history of organisms. By examining the fossil record, scientists can determine the morphological characteristics of ancient organisms and how they are related to modern organisms. This information can be used to support or refute different hypotheses about the evolutionary history of life.
Cell biology can also provide evidence for different hypotheses about the tree of life. For example, the presence or absence of certain cellular features, such as the presence of peptidoglycan in bacterial cell walls or the occurrence of unique metabolic pathways, can help to distinguish between different groups of organisms and support different hypotheses about their relationships.
In summary, while DNA sequence data is a powerful tool for understanding the evolutionary history of life and for determining the relationships between different groups of organisms, the fossil record and cell biology can also provide important evidence for testing different hypotheses about the tree of life. Combining evidence from multiple sources is often necessary to obtain a more complete picture of the evolutionary history of life.
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when two or more monomers join together to form a polymer, water is produced. this is called what?
When two or more monomers combine to create a polymer, a reaction called a dehydration or condensation occurs, which results in the production of water.
DefinitionCovalent bonds are used to join the monomers together to create polymers, which are bigger molecules. Monomers produce water molecules as byproducts as a result of this process. Dehydration synthesis, which literally translates to "to bring together while losing water," is the term used to describe this kind of process.Covalent bonds are created when one monomer combines with another and releases a water molecule. The terms "dehydration reactions" or "condensation reactions" refer to these processes.Through hydrolysis processes, in which the addition of a water molecule lyses (or breaks) a link), polymers are converted into monomers.For more information on polymerization reaction kindly visit to
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What level of protein structure has α helixes or β pleated sheets?
The level of protein structure that has α helixes or β pleated sheets is the Secondary Protein Structure.
The Secondary Protein Structure refers to the three-dimensional structure of individual polypeptide chains. The arrangement of these polypeptide chains includes helixes, pleated sheets, and a few unique forms.
The right-handed spiral structure of the polypeptide backbone results in the formation of alpha helices. The amide group of one amino acid forms hydrogen bonds with the carbonyl group of the amino acid four places downstream, stabilising this secondary structure.
On the other hand, when two or more polypeptide backbones are arranged side by side, pleated sheets are created. The sheets are held together by hydrogen bonds formed by the side chains of the amino acids on the backbones.
This secondary structure is critical for protein stability and has a role in functional activity. Proteins' tertiary structure, or the overall three-dimensional form of the protein, is dependent on the secondary structure of the protein.
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Dump the sand along one side of the pan and form a shoreline, as shown in the
image. Fill the pan with room temperature water so there's at least one inch of water
in the pan and the top of the shoreline is above the water. If you are using food
coloring, add a few drops to your oil and mix thoroughly. Pour the oil in the middle of
the ocean you created, and write down what you observe.
The oil will be found to float on the surface of the water
What happens when oil is poured into an ocean?When oil is spilled into an ocean, it can have severe environmental impacts. Oil is a toxic substance that can harm marine life, such as fish and birds, and their habitats.
The oil floats on the surface of the water, forming a slick that can cover large areas. This can limit the amount of light and oxygen that penetrate the water, killing plants and animals that live near the surface. The oil can also coat birds and sea mammals, making it difficult for them to fly or swim, and potentially causing them to suffocate.
Oil can also contaminate the food chain, as small organisms that are covered in oil can be eaten by larger organisms, leading to the accumulation of toxic chemicals in their bodies.
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an ecologist estimated 800 star-nosed moles, condylura cristata, per square mile in one woodlot and 1,600 per square mile in another woodlot. what was the ecologist comparing?
An ecologist calculated that there were 1,600 star-nosed moles (Condylura cristata) per square mile in one woodlot and 800 in another. The comparisons that ecologist made are density of star-nosed moles
The ecologist was comparing the density of star-nosed moles (Condylura cristata) between two different woodlots, specifically the number of moles per square mile.
The ecologist estimated that there were 800 star-nosed moles per square mile in one woodlot and 1,600 per square mile in another woodlot.
The term "density" refers to the number of individuals of a particular species per unit area or volume of habitat, and it is an important metric for understanding population dynamics and ecology.
By comparing the densities of star-nosed moles between the two woodlots, the ecologist may be able to identify factors that contribute to differences in population size, such as variations in food availability, predator abundance, or habitat quality.
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in a cross between a pure breeding tall plant (dominant) (tt) and a pure breeding dwarf plant (recessive) (tt) the genotype of the offspring will be:
In a cross between a pure-breeding tall plant (dominant) (TT) and a pure-breeding dwarf plant (recessive) (tt), the genotype of the offspring will all be heterozygous (Tt) for the gene that determines plant height.
This is because the tall plant is homozygous dominant (TT) for the trait of plant height, and the dwarf plant is homozygous recessive (tt).
When these two plants are crossed, all of the offspring will inherit one T allele from the tall parent and one t allele from the dwarf parent, resulting in a genotype of Tt for all of the offspring.
The phenotype, or physical appearance, of the offspring, will be tall, as the T allele is dominant and masks the expression of the recessive t allele.
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the thoracic and sacral curvatures of the vertebral column, which develop to accommodate the thoracic and abdominopelvic viscera, are classified as
The thoracic and sacral curvatures of the vertebral column, which develop to accommodate the thoracic and abdominopelvic viscera, are classified as primary curves.
In general , the thoracic and sacral curvatures are also known as the primary curves because they are found in the fetus and often remains the same in the adult. During the developmental period in child they lift their head, and begins to assume an upright position, this when the secondary curves known as cervical and lumbar develop.
Their are other curves present known as kyphotic curve which is convex towards the back of the spine. A lordotic curve is concave towards the back of the spine found in the cervical and lumbar levels of the spine.
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Can someone please help me with this I’ll make you brainliest
Forces of Evolution
The conditions for Hardy-Weinberg equilibrium are unlikely to be met in real populations. The Hardy Weinberg theorem also describes populations in which allele frequencies are not changing. By definition, such populations are not evolving. How does the theorem help us understand evolution in the real world?
From the theorem, we can infer factors that cause allele frequencies to change. These factors are the forces of evolution. There are four such forces: mutation, gene flow, genetic drift, and natural selection.
Mutation
Mutation creates new genetic variation in a gene pool. It is how all new alleles first arise. In sexually reproducing species, the mutations that matter for evolution are those that occur in gametes. Only these mutations can be passed to offspring. For any given gene, the chance of a mutation occurring in a given gamete is very low. Thus, mutations alone do not have much effect on allele frequencies. However, mutations provide the genetic variation needed for other forces of evolution to act.
Gene Flow
Gene flow occurs when people move into or out of a population. If the rate of migration is high, this can have a significant effect on allele frequencies. Both the population they leave and the population they enter may change.
During the Vietnam War in the 1960s and 1970s, many American servicemen had children with Vietnamese women. Most of the servicemen returned to the United States after the war. However, they left copies of their genes behind in their offspring. In this way, they changed the allele frequencies in the Vietnamese gene pool. Was the gene pool of the American population also affected? Why or why not?
Genetic Drift
Genetic drift is a random change in allele frequencies that occurs in a small population. When a small number of parents produce just a few offspring, allele frequencies in the offspring may differ, by chance, from allele frequencies in the parents. This is like tossing a coin. If you toss a coin just a few times, you may by chance get more or less than the expected 50 percent heads or tails. In a small population, you may also by chance get different allele frequencies than expected in the next generation. In this way, allele frequencies may drift over time. Genetic drift occurs under two special conditions. They are called bottleneck effect and founder effect.
1. Bottleneck effect occurs when a population suddenly gets much smaller. This might happen because of a natural disaster, such as a forest fire. By chance, allele frequencies of the survivors may be different from those of the original population.
2. Founder effect occurs when a few individuals start, or found, a new population. By chance, allele frequencies of the founders may be different from allele frequencies of the population they left.
Answer:
Explanation:
1. The forces of evolution are the mechanisms that drive the process of evolution and lead to changes in populations over time. There are four main forces of evolution:
Natural Selection: This is the process by which certain traits become more or less common in a population over time due to differences in survival and reproductive success. Individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring.
Genetic Drift: This is a random change in the frequency of an allele (a variant form of a gene) in a population due to chance events, such as a genetic mutation or the death of individuals carrying certain alleles.
Mutation: This is the process by which new genetic information is introduced into a population. Mutations can lead to new traits and can be the source of variation that drives evolution.
2. Mutations are changes in the DNA sequence of an organism, and they can play a significant role in the process of evolution. There are several types of mutations that can affect evolution, including:
Point mutations: These are mutations that change a single nucleotide in the DNA sequence, which can lead to changes in the amino acid sequence of a protein and potentially affect its function.
Insertion and deletion mutations: These mutations result in the addition or removal of nucleotides in the DNA sequence, respectively. They can disrupt the reading frame of a gene and change its function or lead to the formation of a premature stop codon, causing a truncated protein to be produced.
Frameshift mutations: These are mutations that shift the reading frame of a gene, causing a significant change in the amino acid sequence of the protein produced.
Chromosomal mutations: These are mutations that affect the structure or number of chromosomes, leading to changes in the quantity or organization of genetic information.
These types of mutations can lead to evolution by producing new variations of traits within a population. If these mutations provide a beneficial advantage, they can increase in frequency within a population through natural selection. Over time, the accumulation of beneficial mutations can lead to the evolution of new species.
Therefore, mutations are important in evolution because they provide the raw material for natural selection to work on, leading to the development of new traits and ultimately to speciation.
3. Yes, the gene pool of the American population was affected by the gene flow described above. Gene flow refers to the transfer of genes from one population to another, and it can have a significant impact on the gene pool of a population. In the case of America, the gene pool was affected by the influx of immigrants from various countries, each bringing their own unique genetic background and diversity.
For example, the American population has a significant contribution from European, African, and Asian ancestry. This mixture of different ancestral gene pools has resulted in a diverse and complex genetic landscape in the American population.
Additionally, the intermarriage between individuals from different ancestral backgrounds has also contributed to the gene flow and the diversity of the American gene pool.
4. Genetic drift is one of the four forces of evolution and refers to a random change in the frequency of an allele (a variant form of a gene) in a population over time. This change can occur due to chance events, such as a genetic mutation or the death of individuals carrying certain alleles.
Genetic drift is particularly important in small populations, where chance events can have a larger impact on the frequency of alleles. For example, in a small population, if a single individual carrying a certain allele dies, the frequency of that allele in the population could decrease significantly. Over time, this random process can lead to the loss of genetic variation in a population and can contribute to the divergence of populations and the formation of new species.
Overall, genetic drift is an important force of evolution that can shape the genetic structure of populations and contribute to the diversity of life on Earth.
5. One special condition under which genetic drift occurs is an isolated population. Genetic drift is a mechanism of evolution that refers to the random fluctuations in the frequency of alleles in a population. In an isolated population, the genetic drift process can be more pronounced because the population size is small, and there is limited gene flow from other populations.
As a result, random events such as mutations, deaths, and migrations can have a greater impact on the frequency of alleles in an isolated population. Over time, these random events can lead to the loss or fixation of alleles, shaping the genetic makeup of the population.
QuestionWhat is true of fluid mosaic model?APhospholipid monolayer is present over protein layerBPhospholipid bilayer is present over protein layerCProtein embedded in phospholipid bilayerDPhospholipid layer is sandwitched between two protein layers.Medium
The correct option is C. SJ Singer and GL Nicolson proposed the fluid mosaic model of the biomembrane or cell membrane in 1972. The protein molecules, according to this hypothesis, are embedded within the phospholipid bilayer.
The fluid mosaic model is an approach to explain how cell membranes are constructed. According to the model, the membrane is like a "mosaic" of many parts made up of a fluid or elastic double layer composed of big protein molecules and lipid molecules. The cytoplasm, the material that lies between a cell's membrane and its nucleus, is enclosed by a thin layer called the cell membrane. The cell membrane prevents hazardous substances from entering while allowing beneficial ones to pass through. The fundamental building elements of living cells are lipids and proteins. They move easily within the cell membrane and perform the role of a network of gates, which allows molecules to flow through the membrane.
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