When did the first homo sapiens arrive in the americas?.
Answer:
18,000 years ago
Explanation:
Most archaeologists accept that humans were in the Americas 18,000 years ago
How did Avery's contributions to the understanding of heredity depend on the work of other scientists?
Answer:
Avery's contributions to the understanding of heredity depended on the work of other scientists, particularly Frederick Griffith. Griffith discovered that genetic material could be transferred between bacteria but did not know what that material was.
Avery and his colleagues expanded Griffith's work through experiments to identify the nature of the genetic material responsible for the transformation of bacteria. They purified various components of the bacteria and tested each one to see if it was responsible for the transfer of genetic information.
Their experiments showed that the genetic material responsible for transformation was DNA, not protein or RNA as some scientists had previously thought. Avery's work was groundbreaking because it provided the first direct evidence that DNA was the molecule responsible for transmitting genetic information from one generation to the next.
However, Avery's work depended on the contributions of other scientists. For example, Oswald T. Avery had previously conducted research on the bacterial transformation in the early 1940s. Avery and his colleagues had also benefited from the discovery of X-ray crystallography by Rosalind Franklin and Maurice Wilkins, which allowed them to examine the structure of DNA more closely.
In conclusion, Avery's contributions to the understanding of heredity were built on the work of other scientists who had made important discoveries before him. Without their work, Avery may not have conducted the experiments that led to the identification of DNA as the genetic material.
Explanation:
Examine the digestive system structures in the figure above. The highest rate of nutrient absorption occurs at location _____. 4 5 1 8.
Answer:
at the illeum
Explanation:
the illeum contains several villi and microvilli that increase surface area for absorption
Which three glands secrete the protein fluids which are constituents of semen?
-seminal vesicles
-prostate gland
-Cowper's gland
-vas deferens
-ovum
The three glands that secrete protein fluids that are constituents of semen are the seminal vesicles, prostate gland, and Cowper's gland.
Seminal vesicles are responsible for producing a thick, sticky fluid that contains various proteins and other substances. The prostate gland produces a thin, milky fluid that also contains proteins and enzymes.
The Cowper's gland produces a clear, slippery fluid that helps to lubricate the urethra during ejaculation.
These fluids combine with sperm from the testes and pass through the vas deferens before being released through the urethra during ejaculation.
The ovum is not involved in the production of semen as it is a female reproductive cell, responsible for fertilization by sperm to create a zygote.
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can someone help me with this worksheet?
According to the punnett square, 1) Phenotype long hair and Tortoise shell. 2) Genotype Ll XBXb 3) Gametes: L XB, L Xb, l XB, l Xb. 4) Phenotype Short hair and Black. 5) Genotype ll XbY. 6) Gametes: l Xb, l Xb, l Y, l Y. 7) 4/16 = 1/4. 8) 4/16 = 1/4. 9) 2/16 = 1/8. 10) 2/16 = 1/8. 11) 0/16. 12) 2/16 = 1/8. 13) 2/16 = 1/8. 14) 1/8. 15) 1/8. 16) 1/8. 17) 1/8. 18) 0/8. 19) 0/8. 20) 1/8. 21) 1/8. 22) 1/8. 23) 1/8.
To answer this question, we will use a punnett square which is the best representation of a cross.
What is a Punnett square?The Punnett square is a graphic representation that shows the different types of gamete combinations according to the alleles involved in a cross.
Punnett square shows the probabilities of getting offspring with different genotypes and their consequent phenotypes.
Let us also remember that,
Codominance is an inheritance pattern in which both alleles are expressedComplete dominance is the inheritance pattern in which the dominant alleles hides the expression of the recessive alleleAutosomal genes are those located in autosomal chromosomesX-linked genes are those located in the X chromosome.In the exposed example, two genes code for two traits,
- Color ⇒ X linked gene ⇒ co-dominant
XB XB → organgeXb Xb → blackXB Xb → tortoise shell- Length ⇒ Autosomal gene ⇒ complete dominance
LL and ll → longll → shortThese genes are independent from each other.
Female
1) Phenotype
Long hairTortoise shell2) Genotype ⇒ Ll XBXb
3) Gametes ⇒ L XB, L Xb, l XB, l Xb
Male
4) Phenotype
Short hairBlack5) Genotype ⇒ ll XbY
6) Gametes ⇒ l Xb, l Xb, l Y, l Y
Cross:
Parentals) Ll XBXb x ll XbY
Punnett square) LXB LXb lXB lXb
lXb LlXBXb LlXbXb llXBXb llXbXb
lXb LlXBXb LlXbXb llXBXb llXbXb
lY LlXBY LlXbY llXBY llXbY
lY LlXBY LlXbY llXBY llXbY
F1) 50% of the progeny are expected to be females
50% of the progeny are expected tp be males
From the whole progeny,
1/8 are expected to be females with long hair and Tortoise shell color, LlXBXb.1/8 are expected to be females with long hair and black color, LlXbXb.1/8 are expected to be females with short hair and Tortoise shell color, llXBXb.1/8 are expected to be females with short hair and black color, llXbXb.1/8 are expected to be males with long hair and orange color, LlXBY.1/8 are expected to be males with long hair and black color, LlXbY.1/8 are expected to be males with short hair and orange color, llXBY.1/8 are expected to be males with short hair and black color, llXbY.7) long hair: 4/16 = 2/8 = 1/4 ⇒ LlXBXb + LlXbXb + LlXBY + LlXbY
8) short hair: 4/16 = 2/8 = 1/4 ⇒ llXBXb + llXbXb + llXBY + llXbY
9) tortoise shell female: 2/16 = 1/8 ⇒ LlXBXb, llXBXb
10) black female: 2/16 = 1/8 ⇒ LlXbXb, llXbXb
11) orange female: 0/16
12) black male: 2/16 = 1/8 ⇒ LlXbY, llXbY
13) orange male: 2/16 = 1/8 ⇒ LlXBY, llXBY
14) long tortoise female: 1/8 LlXBXb
15) short tortoise female: 1/8 llXBXb
16) long black female: 1/8 LlXbXb
17) short black female: 1/8 llXbXb
18) long orange female: 0/8
19) short orange female: 0/8
20) long black male: 1/8 LlXbY
21) short black male: 1/8 llXbY
22) long orange male: 1/8 LlXBY
23) short orange male: 1/8 llXBY
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Farmer Joe raises milk cows. In order to increase efficiency, he chooses the cows that produce the most milk and only allows these cows to reproduce.
This process is known as
A. selective breeding.
B. recombinant technology.
C. Mendelian genetics.
D. genetic engineering
Answer:
A. selective breeding.
Explanation:
Selective breeding, also known as artificial selection, is the process of breeding plants and animals for specific desirable traits. In the case of Farmer Joe, he is selecting the cows that produce the most milk and only allowing them to reproduce. By doing this, he is increasing the frequency of the genes responsible for high milk production in his herd. Over time, this results in a population of cows with a higher average milk production than the original population. Selective breeding has been used for thousands of years by humans to improve the quality of crops and livestock. This process has led to the development of many of the plant and animal species that we rely on today.
How did scientists probably date the extrusion and intrusion?
The scientists probably date the extrusion and intrusion through dating a sample of that rock, Radioactive dating.
How do scientists date intrusions and extrusions?Radioactive dating can be seen as one that is been used by the scientist and can be considered as one that provide the ages of particles, however in this case not the sedimentary rock as a whole.
It should be noted that hrough dating a sample of that rock, thenthe extrusion can be known which can be250 million years old however the intrusion extends from the bottom layer up to the earliest one.
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A scientist is studying a population of 100 lizards. Find the chi-square of AA=75 observed, Aa=15 observed, aa=10 observed
The chi-square value for the observed genotype frequencies for a population of 100 lizards is approximately 161.63.
To find the chi-square value for the observed values of the genotypes (AA = 75, Aa = 15, aa = 10) in a population of 100 lizards, we need to compare them with the expected values under a specific hypothesis.
First, we need to determine the expected genotype frequencies based on a specific hypothesis or assumption. Let's assume that the population is in Hardy-Weinberg equilibrium, which assumes random mating and no evolutionary forces at play. In that case, the expected genotype frequencies can be calculated based on the allele frequencies.
Let's assume that the allele frequencies are p and q, where p represents the frequency of the dominant allele (A) and q represents the frequency of the recessive allele (a). In a population in Hardy-Weinberg equilibrium, the expected genotype frequencies can be calculated as follows:
AA = p² * total population
Aa = 2pq * total population
aa = q² * total population
Since we don't have the allele frequencies, we cannot calculate the exact expected values. However, let's assume that the allele frequencies are p = 0.6 and q = 0.4.
Expected genotype frequencies:
AA = (0.6)² * 100 = 36
Aa = 2 * 0.6 * 0.4 * 100 = 48
aa = (0.4)² * 100 = 16
Now, we can calculate the chi-square value using the formula:
chi-square = Σ ((observed - expected)² / expected)
chi-square = ((75 - 36)² / 36) + ((15 - 48)² / 48) + ((10 - 16)² / 16)
chi-square = (39² / 36) + (33² / 48) + (6² / 16)
chi-square = 136.5 + 22.88 + 2.25
chi-square = 161.63
Therefore, the chi-square value for the observed genotype frequencies is approximately 161.63.
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Earth is composed of four open systems that work togetherâthe atmosphere, the hydrosphere, the biosphere, and the geosphere. The atmosphere refers to all air around you as well as the air that extends from the surface of the Earth into space. The hydrosphere refers to Earthâs water; this includes oceans, lakes, glaciers, rivers, streams, and groundwater. The biosphere refers to all organisms on Earth, whether they live in air, on land, or in water. The geosphere refers to the Earthâs interior, rocks, minerals, landforms, and processes that shape the Earthâs surface. Carbon is one of the six elements that are common to all living things. It is the basis for all life on Earth. Carbon moves thr
Carbon is released back into the atmosphere through processes like respiration, combustion, and volcanic eruptions, thus completing the cycle.
The four open systems that work together on Earth: the atmosphere, the hydrosphere, the biosphere, and the geosphere. Also it is mentioned that carbon is one of the six elements common to all living things and is the basis for life on Earth.
The atmosphere consists of all the air surrounding us, extending from the Earth's surface into space. The hydrosphere refers to all of Earth's water, including oceans, lakes, glaciers, rivers, streams, and groundwater. The biosphere encompasses all living organisms on Earth, whether they inhabit air, land, or water. Finally, the geosphere relates to Earth's interior, rocks, minerals, landforms, and the processes that shape the Earth's surface.
Carbon moves through these systems in a continuous cycle, known as the carbon cycle. This cycle plays a critical role in sustaining life on Earth. It begins with the atmosphere, where carbon dioxide is absorbed by plants during photosynthesis. The carbon is then transferred to the biosphere when animals consume these plants. When organisms die and decompose, carbon is returned to the geosphere.
Finally, carbon is released back into the atmosphere through processes like respiration, combustion, and volcanic eruptions, thus completing the cycle.
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Read the following sentences from the text. "But some creatures have just a single cell, like an amoeba. They are called unicellular organisms. Other creatures, like us human beings, are collections of cells. These are called multicellular organisms. Multicellular organisms can range in size from brown algae to large animals like elephants and whales, which have trillions of cells. "
What can be concluded about cells based on this information?
The given text discusses the concept of cellular organization in living organisms. It explains that some organisms, such as amoebas, consist of just one cell, which are called unicellular organisms.
In contrast, more complex creatures like humans are made up of collections of cells and are called multicellular organisms.
The text also points out that multicellular organisms can range in size, from brown algae to large animals like elephants and whales.
This illustrates the diversity of living organisms and emphasizes the role of cells in building and sustaining life.
Overall, the text highlights the importance of cellular organization in the structure and function of living organisms.
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Select all that apply for the following alternative pathway: C4 plants.
Multiple select question.
A)
mostly everywhere
B)
very hot, dry habitats
C)
sunny, tropical habitats
D)
occurs in sugarcane and corn
E)
occurs in cacti, jade plants, and pineapple
F)
fixes carbon dioxide into three-carbon molecules
G)
fixes carbon dioxide into four-carbon molecules
H)
fixes carbon dioxide into organic molecules at night
I)
allows for regular carbon dioxide uptake and water loss
J)
allows for sufficient carbon dioxide uptake and minimizes water loss
The alternative pathway in C4 plants involves several important characteristics that allow for efficient photosynthesis in arid environments. The correct option are B) very hot, dry habitats, C) sunny, tropical habitats , D) occurs in sugarcane and corn. G) fixes carbon dioxide into four-carbon molecules H) fixes carbon dioxide into organic molecules at night and J) allows for sufficient carbon dioxide uptake and minimizes water loss.
First, C4 plants are commonly found in plants such as cacti, jade plants, and pineapples that are adapted to dry conditions. Secondly, the pathway involves fixing carbon dioxide into organic molecules at night, which is known as crassulacean acid metabolism (CAM). This allows for plants to minimize water loss during the day by keeping their stomata closed and still be able to fix carbon dioxide for photosynthesis.
The alternative pathway in C4 plants also allows for sufficient carbon dioxide uptake. This is due to the presence of specialized mesophyll cells that have high levels of the enzyme PEP carboxylase, which can capture carbon dioxide even when levels are low. The captured carbon dioxide is then transported to the bundle sheath cells, where it is further processed through the Calvin cycle. This process allows for efficient use of carbon dioxide and minimal water loss through transpiration.
Overall, the alternative pathway in C4 plants is an important adaptation that allows for efficient photosynthesis in arid environments. It involves several important characteristics, including fixing carbon dioxide into organic molecules at night, specialized mesophyll cells, and efficient use of carbon dioxide. These adaptations help plants to survive and thrive in harsh, dry environments.
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Contrast the effects bacteria have on the body to the effects that parasites have
Bacteria and parasites are both types of microorganisms that can have significant effects on the body, but they differ in several ways.
Effects of Bacteria on the Body:
Bacteria can be either harmful or beneficial to the body.
Harmful bacteria can cause infections such as strep throat, urinary tract infections, pneumonia, and food poisoning.
Bacteria can also contribute to the development of chronic conditions such as acne and periodontal disease.
Beneficial bacteria in the gut can aid in digestion and absorption of nutrients, and can also help regulate the immune system.
Effects of Parasites on the Body:
Parasites are typically harmful to the body and can cause a variety of health problems.
Parasites can cause infections such as malaria, toxoplasmosis, and giardiasis.
Parasites can also contribute to the development of chronic conditions such as chronic fatigue syndrome and irritable bowel syndrome.
Parasites can damage tissues, organs, and cells, leading to inflammation, organ dysfunction, and other health problems.
In summary, while both bacteria and parasites can have significant effects on the body, bacteria can be either harmful or beneficial, while parasites are typically harmful and can cause a wide range of health problems.
While this answer may provide helpful information regarding your assignment, it is important to remember that using it verbatim could be seen as plagiarism. To avoid this, it is best to cite your sources and use your own words to ensure a better answer.
~~~Harsha~~~
What is the Solution?
At rest, the tropomyosin molecule is held in place by:.
At rest, the tropomyosin molecule is held in place by the troponin complex.
The troponin complex is made up of three subunits - troponin C, troponin I, and troponin T. Troponin C is the calcium-binding subunit, troponin I inhibits the interaction between myosin and actin, and troponin T anchors the troponin complex to the tropomyosin molecule.
When calcium ions bind to troponin C, a conformational change occurs in the troponin complex, causing troponin I to release its inhibition on the interaction between myosin and actin. This allows for the formation of cross-bridges between the myosin heads and the actin filaments, leading to muscle contraction.
In summary, the troponin complex plays a critical role in regulating muscle contraction by controlling the positioning of the tropomyosin molecule. Without this complex, the myosin heads would not be able to interact with the actin filaments, and muscle contraction would not be possible.
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Name two parameters used in estimating cell size.
Identified coping strategy, explain how the relevant can help in resolving an unhealthy relationship ,also give an example in your explanation
Coping strategies are an important tool to help individuals navigate difficult situations and to improve an unhealthy relationship.
Coping strategies involve using problem-solving skills, communication skills, and other positive behaviors to resolve conflict and improve the relationship. For example, communication skills such as active listening, expressing empathy, and expressing needs can help to create a safe space for both parties to share their feelings and needs.
This can help to create a trusting and secure relationship by allowing all parties to feel heard and respected. Additionally, problem-solving skills can help to find solutions to issues, rather than just focusing on the problems.
By breaking down the issues into smaller parts and working through them, both parties can gain a better understanding of each other and the conflict. With these coping strategies, individuals can better understand their own emotions and the emotions of their partner, leading to a healthier and more fulfilling relationship.
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The basic proposition of the epidemiologic transition theory is that the increases in life expectancy have been caused primarily by changes in the age distribution of
The basic proposition of the epidemiologic transition theory is that increases in life expectancy have been caused primarily by changes in the age distribution of the population.
This is due to shifts in the leading causes of mortality from infectious and communicable diseases to non-communicable and chronic diseases. As societies advance and public health improves, the burden of disease shifts to older age groups, contributing to increased life expectancy.
In the early stages of development, societies typically experience high mortality rates due to infectious and communicable diseases such as pneumonia, tuberculosis, and diarrheal diseases.
These diseases tend to affect people of all ages, including infants and children, resulting in relatively low life expectancies.
As societies advance and public health measures improve, there is a decline in mortality rates from infectious diseases. This decline is often accompanied by improvements in sanitation, nutrition, and access to healthcare.
As a result, people are more likely to survive into adulthood, and the burden of disease begins to shift towards non-communicable and chronic diseases.
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The basic proposition of the epidemiologic transition theory is that the increases in life expectancy have been caused primarily by changes in the age distribution of diseases and mortality patterns within a population and improvements in public health measures.
While a lot of people died during the Spanish Flu Pandemic, many people were also infected and survived. Why do you think it is beneficial for a pathogen to work without killing the host?
Which of the following are types of adaptations of desert plants that enable them to survive and reproduce? (Choose all that apply.)
Flower adaptations
Stem and leaf adaptations
Behavioral adaptations
Root adaptations
The types of adaptations of desert plants that enable them to survive and reproduce are stem and leaf adaptations and root adaptations
What is adaptationBy changing throughout time in response to external forces, organisms can better survive and reproduce in their particular habitat. This process is known as adaptation. Morphological, physiological, and behavioral adaptations can all be the result of natural selection, genetic drift, or other processes.
The biological process of reproduction is how organisms create children that receive their genetic make-up. Most species reproduce by joining their male and female gametes to create a zygote, which then grows into a new person. The continuation of a species and the transmission of genetic features from one generation to the next depend on reproduction. Reproduction can take place in a sexual or asexual way.
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The majority of total daily energy expenditure (TDEE) is devoted to attributable to basal metabolic rate (BMR), the amount of energy spent to meet the body's basic ________ needs when it is at rest
The majority of total daily energy expenditure (TDEE) is devoted to basal metabolic rate (BMR), the amount of energy spent to meet the body's basic physiological needs when it is at rest. These needs include functions such as breathing, circulating blood, and maintaining body temperature. BMR is affected by various factors such as age, gender, body composition, and thyroid hormone levels. It accounts for about 60-75% of total daily energy expenditure in most people.
What is BMR ?
BMR also known as basal metabolic rate is the number of calories that a person's body burns under normal circumstances or while performing the basic life-sustaining activities that a person does in his or her day-to-day life.
Exercise increases BMR as the heart rate of the person increases while doing exercise, also it is an energy-demanding activity as hard-working muscles require more energy to burn as a result more energy is spent during exercise. exercise such as cardio burns a lot of calories from one's body due to higher blood flow and rapid increase in the heart rate.
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Essay writer
A gene helps determine how the pigment melanin is distributed on human skin.
Having freckles or not having freckles are traits determined in part by this gene.
Write an explanation for why some people have one trait and other people have
the other. Be sure to use the terms allele and chromosome in your answer.
Answer:
Genes have different versions, called alleles. Alleles are one reason some people have freckles and others do not. A person who has freckles inherited alleles that produce freckles. A person with no freckles inherited different alleles that don't produce freckles.
Explanation:
That was the sample answer.
Hemoglobin is the protein in red blood cells that binds oxygen. If a mutation occurs in the DNA that codes for hemoglobin, the structure of hemoglobin can change. The change in structure of hemoglobin can then change the shape of red blood cells, and some mutations can cause red blood cells to become sickle-shaped.
Sickled red blood cells carry less oxygen than normal red blood cells. What does this demonstrate about mutations in the DNA that codes for hemoglobin?
A.
These mutations can change the structure of oxygen so that it does not bind to hemoglobin.
B.
These mutations decrease the amount of oxygen available to bind with hemoglobin.
C.
These mutations are unable to affect the structure and function of hemoglobin.
D.
These mutations can change the structure and function of hemoglobin.
The fact that sickled red blood cells carry less oxygen than normal red blood cells demonstrates that the mutations in the DNA that codes for hemoglobin can change the structure and function of hemoglobin.
The correct option is D.
What is hemoglobin?Hemoglobin is a protein that is found in red blood cells that carries oxygen from the blood to cells and tissues where they are needed.
The function of hemoglobin is related directly to its structure.
A mutation in the gene that codes for hemoglobin will result in adefor ation of the structure of hemoglobin, us rendering it unable to transport oxygen effieciently.
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Some breeds of beef cattle have two color options, red and black, where the black version of the gene (B) is dominant over the red version (b).
The different forms of the beef cattle color gene are called ___
The different forms of the beef cattle color gene are called alleles. Alleles are alternate forms of the same gene, and they can be either dominant or recessive.
In the case of the beef cattle color gene, the black version of the gene (B) is dominant over the red version (b). This means that if both the dominant and the recessive alleles are present, the black color will be expressed in the cow. However, if two recessive alleles are present, then the red color will be expressed in the cow.
Dominant alleles are always expressed in an organism, while recessive alleles are only expressed when two of them are present. Dominant alleles can also be passed on to offspring, while recessive alleles can only be passed on if two of them are present.
This is why it is important to understand the genetic makeup of a breed before breeding. By studying the alleles and their expression, breeders can ensure that the desired phenotype is expressed in the offspring.
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the following sequence of dna is part of the normal, wild-type gene. 3' atg cgg gta gtt agc cga tag 5' a deletion occurs during dna replication, causing the guanine shown in red to be removed from the nucleotide strand. what effect is this most likely to have on the final protein?
The sequence given is in the 5' to 3' direction and represents a segment of DNA that codes for a protein. The start codon "ATG" indicates the beginning of the coding region and the stop codon "TAG" indicates the end of the coding region.
The deletion of the guanine (G) from the sequence would result in a frameshift mutation since the deletion would shift the reading frame of the codons. This would cause all the codons downstream of the deletion to be different from the original sequence.
The new sequence would be: 3' atg cgg gta tta gcc gat ag 5'
The new codons downstream of the deletion would be different, which would result in a different amino acid sequence being translated. This could potentially alter the structure and function of the final protein. The effect of this frameshift mutation on the protein would depend on the specific location of the deletion and the resulting altered sequence of codons.
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Why is it important to study variations in monkey populations?
Studying variations in monkey populations is important because it can help us better understand the evolution of primates, including humans.
By studying the genetic, behavioral, and physiological variations among different monkey populations, researchers can gain insights into how traits are passed down through generations and how natural selection shapes these traits over time.
This information can also be used to inform conservation efforts, as understanding the genetic diversity and geographic distribution of different monkey populations can help guide conservation efforts aimed at protecting these endangered species.
Additionally, studying monkey populations can shed light on the ecological and environmental factors that influence animal behavior and adaptations, which can inform our understanding of broader ecological systems.
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In Africa, elephant populations have declined due to poaching, which is illegally hunting elephants for their tusks. In the past, only about two percent of female elephants were born tuskless. A recent study found that 98 percent of the 174 female calves born in one national park had no tusks. Which of the following statements is supported by this mathematical representation?
A. Elephants without tusks are surviving and reproducing while elephants with tusks are not.
B. Elephants no longer need tusks because their habitats have been changing.
C. Female elephants do not need tusks to successfully rear their young.
D. Male elephants are growing tusks more quickly than female elephants are.
Natural selection selects beneficial alleles and and phenotypes, and increases their frequency in the population. Option A. Elephants without tusks are surviving and reproducing while elephants with tusks are not.
What is natural selection?
Natural selection is an evolutive force that favors an allele or act against it, depending on how the allele affects the fitness of individuals. It selects beneficial alleles and increases their frequency in the population.
The phenotype that expresses the best fitness results in higher survival, fertility, and reproductive rates. Aptitude -fitness- must be significant to the natural selection act in its favor.
Adaptation, acchieved by natural selection, is closely related to selective pressures.
Selective pressure is applied by different organisms or conditions that influence the survival rate of a certain phenotype. It influences the probability of a genotype leaving its gametes to the following generations.
In the exposed example,
Selective pressure ⇒ poachingoriginal phenotype ⇒ tuskednew phenotype ⇒ tusklessBeing tuskless increased the individuals' fitness so natural selection favored this new phenotype and increased its frequency in the population.
Option A. Elephants without tusks are surviving and reproducing while elephants with tusks are not.
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How do the chromosomes at the end of meiosis i compare with the chromosomes at the end of meiosis ii?
At the end of meiosis I, each chromosome still consists of two sister chromatids, but the number of chromosomes is reduced by half.
This reduction is due to the separation of homologous chromosomes, which are pulled to opposite poles of the cell during the first division. At the end of meiosis II, the sister chromatids finally separate, resulting in four haploid daughter cells, each containing a single chromosome. So, at the end of meiosis II, the chromosomes are in their haploid form, with only one chromatid per chromosome. In summary, the chromosomes at the end of Meiosis I are still composed of sister chromatids, while the chromosomes at the end of Meiosis II are single chromatids in each of the four haploid cells.
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When a species fails to produce any more
descendants, it is said to
A. be extinct
B. be divergent
C. have speciated
D. have become isolated
Answer:
When a species fails to produce any more descendants, it is said to be extinct .
Explanation:
What prevents backwards flow of urine from the bladder into the ureters?.
The ureters enter the bladder obliquely and are surrounded by a muscular valve called the ureterovesical junction, which prevents the backwards flow of urine from the bladder into the ureters.
The ureters are muscular tubes that carry urine from the kidneys to the bladder. They enter the bladder obliquely, meaning that they do not enter the bladder at a right angle but at an angle that causes the ureter to be compressed when the bladder fills with urine.
Additionally, the ureterovesical junction, or the point at which the ureter meets the bladder, is surrounded by a muscular valve that contracts to prevent urine from flowing backwards into the ureters.
This valve, called the vesicoureteral valve, is made up of smooth muscle and is under autonomic control, meaning that it is regulated by the nervous system. The combination of the oblique angle of the ureter and the muscular valve at the ureterovesical junction helps to ensure that urine flows in one direction, from the kidneys to the bladder, and does not flow backwards into the ureters.
However, in some cases, such as with vesicoureteral reflux, the valve may not function properly, leading to the backwards flow of urine and potentially causing urinary tract infections and other complications.
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If a single cycle of PCR takes 5 minutes, it should it take _______ minutes to amplify one double-stranded molecule into 64
If a single cycle of PCR takes 5 minutes, it should it take 30 minutes to amplify one double-stranded molecule into 64
PCR (Polymerase Chain Reaction) is a laboratory technique that can be used to amplify DNA fragments. In each cycle of PCR, the amount of DNA is doubled.
Therefore, to determine how long it would take to amplify one double-stranded molecule into 64 molecules, we need to calculate the number of cycles required.
To amplify one double-stranded molecule into 64, it would require 6 cycles of PCR since 2^6 = 64.
If each cycle of PCR takes 5 minutes, then 6 cycles would take a total of 30 minutes (6 cycles x 5 minutes per cycle). Therefore, it would take 30 minutes to amplify one double-stranded molecule into 64 using PCR.
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