Summarize how the fossil cetacean ancestors changed over time. Give at least one example of a specific trait and how it changed

When an ecosystem is disturbed by fire or toxic chemicals, the effects will be a disturbance that may affect the trophic chain by altering the balance of producer organisms.

The major effects of ecological disturbance include the reduction of natural populations such as plants which represent the primary producers in terrestrial ecosystems, and it may lead to a unbalance in the whole ecosystem's homeostasis.

Therefore, with this data, we can see that the major effects of ecological disturbance include the dramatic reduction in producer organisms.

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That's correct! Prokaryotes, such as bacteria, typically have a single, circular chromosome that contains all of their genetic material. This chromosome is located in the cytoplasm of the cell and is not enclosed in a membrane-bound nucleus.

A nucleus is a specialized structure that is found within cells. It is the central part of the cell that contains genetic material in the form of DNA (deoxyribonucleic acid). The nucleus is responsible for regulating gene expression, controlling cell division, and maintaining the integrity of the genetic material.

In eukaryotic cells, which include animals, plants, fungi, and protists, the nucleus is a membrane-bound organelle that is surrounded by a double membrane called the nuclear envelope. The nuclear envelope has small pores that allow for the exchange of molecules between the nucleus and the rest of the cell.

Prokaryotic cells, which include bacteria, do not have a distinct nucleus. Instead, their genetic material is contained in a region called the nucleoid, which is not surrounded by a membrane.

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The term that best describes a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway is feedback inhibition.

What is feedback inhibition? Feedback inhibition is a type of metabolic regulation that allows cells to regulate their metabolism through the use of enzymes. The rate of a metabolic pathway is slowed by feedback inhibition when an enzyme at the beginning of the pathway is inhibited by its end product.

The pathway continues to function as long as the end product is in low demand, but as the end product accumulates, it eventually inhibits the pathway, preventing excess synthesis of the end product.

Feedback inhibition is a method of regulating enzymatic activity in which the activity of an enzyme is inhibited by the product of the pathway it is involved in. It is a negative feedback mechanism that controls the rate of the metabolic pathway.

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Leptin is released from fat cells and results in a decrease in appetite.

Leptin is a hormone that is released by adipose tissue and is responsible for regulating energy balance and appetite. It has an inhibitory effect on hunger and is responsible for signaling to the brain that the body has enough energy stores.

The brain uses leptin levels to gauge the body's energy status. When leptin levels are high, the brain perceives that the body has sufficient energy stores and, as a result, reduces hunger and increases energy expenditure. When leptin levels are low, the brain perceives that the body is in a state of negative energy balance and, as a result, increases hunger and decreases energy expenditure.

Leptin also plays a role in the regulation of other physiological processes, including immune function, bone metabolism, and reproductive function. Leptin resistance, a condition in which the brain fails to respond to leptin signaling, can lead to increased hunger and decreased energy expenditure, which can contribute to the development of obesity.

In summary, the fat cells release leptin to signal hunger.

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Different types of photopigments differ from one another based on the specific wavelengths of light they absorb and the color vision they enable.

Photopigments are proteins found in the cone cells of the retina, responsible for detecting light and color vision.

There are three types of cone cells in the retina, each containing a different type of photopigment that responds to different wavelengths of light: blue, green, and red. These photopigments are called opsin and they bind with a chromophore called retinal to form the complete photopigment.

Each type of opsin has a slightly different amino acid sequence, which determines the wavelengths of light it absorbs most effectively, and hence the color vision it enables. For example, the blue opsin absorbs shorter wavelengths of light, while the red opsin absorbs longer wavelengths. When different combinations of photopigments are stimulated by light, the brain can interpret the information to perceive a range of colors. Overall, the differences in the amino acid sequences of the opsin photopigments determine their spectral sensitivity and enable us to perceive different colors.

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The function of the basilar membrane, hair cells, and tectorial membrane are as follows: The sound waves cause the basilar membrane to vibrate first. The hearing receptors are embedded in the hair cells. The structure that bends the hearing receptors but does not vibrate itself is the tectorial membrane. The hearing receptors are connected to the basilar membrane by supporting cells. As a result of this vibration, hair cells are bent. Hearing receptors are called hair cells.

The cochlea is an organ of the inner ear that is shaped like a snail shell. It contains tiny hair cells that are responsible for picking up sound vibrations and transforming them into nerve signals that can be interpreted by the brain.

The cochlea contains a fluid-filled cavity that is set in motion by sound vibrations. The basilar membrane is a structure that runs along the length of the cochlea and separates the fluid-filled cavity into two chambers. When sound vibrations enter the cochlea, they cause the basilar membrane to vibrate.

This vibration causes the hair cells, which are embedded in the basilar membrane, to bend. The tectorial membrane, which is located above the hair cells, does not vibrate but is responsible for bending the hair cells when the basilar membrane vibrates. The bending of the hair cells causes electrical signals to be sent to the brain, which are then interpreted as sound.

Hence, the sound waves cause the basilar membrane to vibrate first. The hearing receptors are embedded in the hair cells. The structure that bends the hearing receptors but does not vibrate itself is the tectorial membrane. The hearing receptors are connected to the basilar membrane by supporting cells. As a result of this vibration, hair cells are bent. Hearing receptors are called hair cells.

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The entering UTP molecule breaks down the pyrophosphate.

The nitrogenous base uracil is one of the four found in the RNA molecule. Except for the substitution of thymine for uracil, all of these nitrogenous bases are also present in deoxyribonucleic acid, including the pyrimidine-derived uracil and cytosine, as well as the purine-derived adenine and guanine (DNA).

DNA uses thymine rather than uracil because it offers a stronger protection against photochemical change and makes the genetic information more robust. To store all the info required for life to function, this is required.

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The male reproductive system includes several structures that work together to produce, store, and deliver sperm. One of the key structures involved in this process is the vas deferens.

The vas deferens, also known as the ductus deferens, is a muscular tube that carries sperm from the epididymis (where sperm mature and are stored) to the urethra. The vas deferens is located within the scrotum and is part of the spermatic cord, which also contains blood vessels, nerves, and other structures.

During ejaculation, the smooth muscles in the wall of the vas deferens contract, propelling the sperm through the duct and into the urethra. From there, the sperm are mixed with seminal fluid from the prostate gland and other accessory glands before being ejaculated from the body.

It is important to note that the vas deferens does not carry sperm from outside the body into the abdominal cavity. Instead, it carries sperm from the testes, where they are produced, to the urethra, where they are ejaculated from the body during sexual activity.

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Physical changes that signal the passage from childhood to adolescence are best described as puberty.

Adolescence is a stage that occurs between childhood and adulthood. Its onset is indicated by pubertal development, and its offset is symbolised by parental independence.

Young individuals go through a lot of changes as they transition into physical adulthood during adolescence. The emergence of the secondary sexual features marks the beginning of prepubescent alterations.

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Answer:

the genes tend to "stick together" during meiosis

Explanation:

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The given statement implies that since Mycoplasmas lack a cell wall containing peptidoglycan, thus they are resistant to penicillin, which interferes with peptidoglycan synthesis. This is an example of structural resistance.

Structural resistance is a resistance mechanism that protects bacteria against the effects of antibacterial agents. The microbial cell's structure and function contribute to the resistance of antibacterial agents.

The bacteria's structure and function include cell membranes, proteins, and organelles. The resistance mechanisms can result from the following:-

Mycoplasmas are a group of bacteria that do not have a cell wall, but they contain a cell membrane that protects the bacteria's cells. Therefore, antibiotics like penicillin that target the bacterial cell wall are ineffective against Mycoplasmas. Hence Mycoplasmas have developed structural resistance to penicillin.

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During the light-dependent reactions of photosynthesis, the thylakoid membrane is the site of the electron transport chain and ATP synthesis.

The thylakoid membrane contains two photosystems, Photosystem I and Photosystem II, that absorb light energy and convert it into chemical energy in the form of ATP and NADPH. The light energy is used to excite electrons in the chlorophyll pigments of the photosystems, which are then transferred to a series of electron carriers in the electron transport chain.

As electrons move through the chain, a proton gradient is established across the thylakoid membrane, which is used to synthesize ATP via ATP synthase. At the end of the electron transport chain, the electrons are used to reduce NADP+ to NADPH, which is then used in the Calvin cycle to synthesize glucose.

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Answer:

Explanation:

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The statement "It favors extremes in traits" is true about disruptive natural selection.

Disruptive natural selection occurs when extreme traits are favored over intermediate traits, leading to a bimodal distribution of traits in a population. This means that individuals with extreme traits at both ends of the distribution have a higher fitness compared to individuals with intermediate traits. As a result, the population becomes less homogeneous and more specialized in the extreme traits that are favored by natural selection.

Oysters of different colors—dark and light—are one instance of disruptive selection. Oysters with dark or light colours can blend in more effectively. Dark oysters can hide behind the shadow of the rocks, whereas light oysters can blend in with the rocks.

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The steps involved in scientific method include observation, research question, hypothesis, experiment, result, conclusion, etc.

Steps of the scientific method in this study:

Observation: The researchers observed that college students often experience high levels of stress and that meditation has been suggested as a possible intervention for stress reduction.

Research question: The researchers formulated a research question: Does meditation reduce stress in college students?

Hypothesis: Based on previous research and theory, the researchers formulated a hypothesis: Meditation reduces stress in college students.

Experiment: The researchers designed an experiment to test their hypothesis. They recruited a group of college students and randomly assigned them to either a meditation group or a control group. The meditation group practiced meditation for eight weeks, while the control group did not.

Data collection: The researchers collected data on participants' stress levels before and after the eight-week intervention period.

Results: The researchers analyzed the data and found that the meditation group had significantly lower levels of stress compared to the control group.

Conclusion: Based on their findings, the researchers concluded that meditation is an effective intervention for reducing stress in college students.

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The neural communication varies greatly from when we are tapped gently on the arm in comparison to when we are slapped across the face. When we slapped that strongly triggers and increases the number of times those neurons fire. But when we tap on the arm that triggers fewer neurons to be fired.

Communication between neurons occurs electrochemically. Neurotransmitter receptors can be found on the dendrites of neighboring neurons. If the impulses from neighboring neurons are strong enough, an action potential will travel the length of the axon to the terminal buttons, releasing neurotransmitters into the synapse in the process.

Many neurotransmitters serve a variety of purposes. Unbalances in a specific neurotransmitter system frequently play a role in psychiatric disorders. As a result, doctors often prescribe psychiatric medications to try to rebalance the neurotransmitters. For a certain neurotransmitter system, drugs can either behave as agonists or antagonists.

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A food chain is usually part of a larger food web.  The food web will show all the feeding relationships in the ecosystem.

A food chain is usually part of a larger food web. A food web represents the complex interconnections between different food chains within an ecosystem, showing the flow of energy and nutrients between different organisms.

In a food web, multiple food chains are interconnected, with some organisms occupying multiple positions as both predators and prey. The concept of a food web highlights the interconnectedness of different organisms within an ecosystem and the importance of maintaining balance and stability in natural systems.

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An elementary reaction is known to be bimolecular. This means that two molecules must collide at the same time. Thus, option C is the correct answer.

Bimolecular reactions are chemical reactions that occur between two reactant molecules. According to reaction kinetics, bimolecular reaction rate laws have second-order kinetics. The reaction rate is proportional to the product of the concentrations of two reactants, so the concentration of two reactants in the collision is necessary. Thus, the reaction is bimolecular. The general formula of the reaction is A + B -> AB. The rate equation of the bimolecular reaction is rate = k [A] [B] or rate = k [A]^2.The order of a reaction is determined by the order of the slowest elementary step. The order of the reaction is 2 when a bimolecular reaction occurs through an elementary step. Thus, option B is incorrect. An elementary reaction only includes a single step. The species present in the reactants and products of an elementary reaction are known as molecules, ions, or atoms. In an elementary reaction, the number of products that form corresponds exactly to the number of reactants that are lost. Thus, option A is also incorrect. Therefore, the correct option is C) Two molecules must collide at the same time.

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The evidence from these Drosophila experiments that the genes for wing shape and bristles are inherited independently of each other is genes for wing shape and bristles are inherited independently of each other.

Since the two genes were on sepаrаte chromosomes, they were аble to do so. Thus, the frequency of аppeаrаnce of these two trаits hаs no relаtionship. They were inherited independently, with no correlаtion or linkаge in the genetic inheritаnce of wing shаpe аnd bristles.

The inheritаnce of а gene is аccomplished by the chromosome it is on. Different trаits cаn be inherited independently of one аnother if they аre locаted on different chromosomes. If two genes аre found on the sаme chromosome, they аre more likely to be inherited together. Genes thаt аre locаted neаr one аnother on the sаme chromosome аre sаid to be linked.

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The type of muscle fibers that are used to maintain posture in the back muscles are primarily slow-twitch fibers or Type I fibers.

These muscle fibers are also known as red fibers due to the presence of myoglobin that binds oxygen in the muscle cell. The function of the back muscles is to maintain posture and support the weight of the upper body. Slow-twitch muscle fibers are best suited for this function as they are able to contract and maintain tension for longer periods of time, without fatiguing quickly. Slow-twitch fibers have a high concentration of mitochondria which are responsible for generating energy for the muscle cell through aerobic respiration. Slow-twitch fibers also have a high concentration of capillaries which deliver oxygen to the muscle cell. This is important as oxygen is required for aerobic respiration to occur which generates energy in the muscle cell. Slow-twitch fibers are also able to store more glycogen than fast-twitch fibers which is another source of energy for the muscle cell during exercise. In summary, the type of muscle fibers that are used to maintain posture in the back muscles are primarily slow-twitch fibers or Type I fibers. These fibers are best suited for this function due to their ability to contract and maintain tension for longer periods of time, without fatiguing quickly.

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In rabbits, black fur (B) is dominant over brown fur (b). The Punnett square is shown below, and both parents are b. homozygous dominant.

A Punnett square is a chart that scientists utilize to predict the likelihood of an offspring inheriting a particular trait. It is a visual representation of Mendelian genetics' fundamental principles. A Punnett square can be used to estimate the chances of an offspring inheriting particular characteristics by organizing the alleles from both parents.

An individual has two copies of the same allele in their DNA sequence, and the alleles are the same. Homozygous dominant alleles are a pair of genes that specify the same characteristics and that are both dominant alleles. As a result, the offspring will inherit black fur in a 100 percent likelihood. The alleles for black fur from both parents are present in the offspring's genome, so the black fur trait will be expressed as a result.

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a population leaves Hardy-Weinberg equilibrium due to selection it can return to the equilibrium by . 1. A large population size 2. No migration (immigration or emigration) 3. No mutation (change in DNA sequence)4. No natural selection 5. Random mating (no selection for mates).

Hardy-Weinberg equilibrium assumes that there is no selection for or against any genotype in the population. In reality, this is rarely the case. If a population's genotypic frequencies deviate from Hardy-Weinberg equilibrium, selection may be one cause.

There are two types of selection: directional selection and stabilizing selection. If a population's genotypic frequencies deviate from Hardy-Weinberg equilibrium, selection may be one cause.

Stabilizing selection occurs when the average genotype is favored over the extremes. In this case, both the favored and disfavored alleles decrease in frequency. There are a few potential scenarios in which a population might return to Hardy-Weinberg equilibrium after leaving it due to selection:

1. If the selection pressure is removed, the population may return to Hardy-Weinberg equilibrium.

2. If the favored allele reaches 100% frequency, the population will return to Hardy-Weinberg equilibrium because there will no longer be any variation in the population.

3. If a new mutation occurs and creates a new allele, the population may return to Hardy-Weinberg equilibrium if the new allele is neutral and does not confer a selective advantage or disadvantage.

4. Finally, if gene flow (migration) is introduced into the population, it may return to Hardy-Weinberg equilibrium.

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The phase of mitosis during which chromosomes line up on the equator of the cell is metaphase. Therefore the correct option is option E.

Mitosis is a cell division process that occurs in most eukaryotic cells. In this process, a parent cell produces two identical daughter cells. Mitosis has five stages: prophase, metaphase, anaphase, telophase, and interphase.

Chromosomes are visible and condense during mitosis, as a result of the coiling of DNA around proteins called histones.Mitosis can be divided into four distinct stages: prophase, metaphase, anaphase, and telophase. During metaphase, the chromosomes line up on the equator of the cell, which is known as the metaphase plate.

The centromeres of the chromosomes are located on the metaphase plate. Chromosomes can then be separated and pulled to opposite poles of the cell during anaphase.

The spindle fibers of the cell, which are microtubules that connect the centrosomes to the chromosomes, are responsible for the separation and movement of the chromosomes. Therefore the correct option is option E.

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Answer:

(a) The structures labelled A and B in the diagram are:

A - Capillaries

B - Alveoli

(1) Healthy lung

(2) Diseased lung

The disease shown in the diagram is emphysema.

(3) Explanation:

Emphysema is a respiratory disease that affects the alveoli, the tiny air sacs in the lungs responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. In emphysema, the walls of the alveoli are damaged, leading to the formation of larger, less efficient air spaces. This causes a reduction in the surface area available for gas exchange, leading to impaired breathing and reduced oxygen supply to the body.

As the walls of the alveoli break down, the lungs lose their elasticity and become less able to expel air. This results in a buildup of air in the lungs, which can cause shortness of breath and other respiratory symptoms. In addition, the capillaries around the alveoli may become damaged, leading to reduced blood flow to the lungs and further reducing the efficiency of gas exchange.

Overall, emphysema reduces the efficiency of the process of gaseous exchange in the lungs by reducing the surface area available for gas exchange and impairing the ability of the lungs to expel air. This can lead to reduced oxygen supply to the body and other respiratory symptoms.

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Drugs that target RNA polymerase are direct inhibitors of transcription.

RNA polymerase is an enzyme that helps to create RNA from DNA. It is an essential enzyme that is involved in gene expression by regulating the transcription of DNA into RNA.

RNA polymerase produces a strand of RNA using one strand of DNA as a template. There are many drugs that target RNA polymerase, and they are used as inhibitors of transcription.

Direct inhibitors of RNA polymerase are commonly used to treat cancer, bacterial infections, and viral infections. These drugs act by blocking the enzyme from synthesizing RNA molecules.

By inhibiting RNA synthesis, these drugs can prevent the expression of certain genes, which can be useful in treating various diseases.

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Reasonable evaluations of evolution in humans today involve considering both the benefits and potential risks that result from evolutionary processes.

In terms of benefits, evolution has allowed for the increase in human lifespan, the ability to better adapt to changing environments, and the improvement of health, amongst other things. Additionally, the process of evolution has allowed us to further understand how species, including humans, are related to one another.

In terms of risks, the increasing speed of evolution can lead to new health problems. Additionally, the process of evolution has the potential to cause significant disruption to the environment, potentially leading to extinction of species. Furthermore, rapid evolutionary changes could lead to a lack of genetic diversity, potentially resulting in the development of genetic diseases.

Overall, the reasonable evaluation of evolution in humans today should take into account both the potential benefits and potential risks that come with evolutionary processes. It is important to be aware of the potential implications of evolutionary changes, in order to be better prepared to address any potential issues that may arise.

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Working draft horses are known for their exceptional strength and endurance, which is partly attributed to their high percentage of slow-twitch muscle fibers.

Slow-twitch muscle fibers are characterized by their ability to contract for longer periods of time, allowing the horse to maintain a sustained level of activity over extended periods. In contrast, fast-twitch muscle fibers are characterized by their ability to contract quickly and powerfully, but for shorter durations. Draft horses are bred and trained for tasks that require prolonged physical exertion, such as pulling heavy loads, which makes the slow-twitch fibers more advantageous. This adaptation has resulted in draft horses having a higher percentage of slow-twitch muscle fibers compared to other horse breeds that are bred for speed and agility.

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The factor that might decrease the rate of change of the population as the logistic curve approaches the carrying capacity is intraspecific competition. Hence, option A is the correct option.

Carrying capacity is defined as the maximum number of species that can be supported in a specific region without the depletion of natural resources. Population growth is sustained until the carrying capacity is reached by the population. When a population grows to its carrying capacity, it means that the environment has reached its maximum limit for a particular species, and further growth will be limited by the available resources.

A logistic curve is a curve that shows population growth and how it approaches its maximum value over time. It plots population growth as a function of time and shows a sigmoidal (S-shaped) curve as the population reaches the carrying capacity.There are different factors that might decrease the rate of change of the population as the logistic curve approaches the carrying capacity. One of the factors that might decrease the rate of change of the population as the logistic curve approaches the carrying capacity is intraspecific competition. Intraspecific competition occurs when members of the same species compete for the same resources. As a result of intraspecific competition, population growth slows down, and the logistic curve begins to approach the carrying capacity.

Therefore, the correct option will be A.

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If you mate a dog with a bbee genotype to a dog with a bbee genotype, you can expect 25% of each phenotype over the course of many litters.

A phenotype is an observable characteristic that arises from an individual's genotype. For example, the color of an individual's eyes, fur, or feathers is a phenotype, as is their ability to taste certain foods or produce specific enzymes. The phenotype is determined by the genotype, or the genetic makeup, of an individual.

A single gene or a group of genes determines an organism's phenotype. The expression of a gene is referred to as its genotype, while the physical, observable characteristics that arise as a result of that expression are referred to as the phenotype.

A Punnett square is a tool used to calculate the possible results of a genetic cross between two parents with known genotypes. A Punnett square can be used to determine the probability of each phenotype or genotype for their offspring when given the parents' genotypes.

In the question, the two parent dogs have a Bbee genotype, which implies they both possess one dominant B allele and one recessive b allele, as well as two copies of the recessive e allele. A Punnett square can be used to determine the possible genotypes and phenotypes of the offspring. When crossing the two parent dogs in the Punnett square, the following results are obtained:

bbEeBbEeBbEebbeeBbEeBbeeBbEeBbEebbeeBbeeBbEebbeeBbeeBeeBbeeBebe

The following phenotypes are expected to occur in the offspring:

brown with eyes that are not white: 1/4 or 25%

brown with eyes that are white: 1/4 or 25%

black with eyes that are not white: 1/4 or 25%

black with eyes that are white: 1/4 or 25%

Thus, in the course of many litters, you can expect a 25% occurrence of each phenotype.

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