Answer:
Melanocytes are a specialized type of skin cell, present in humans and other animals. These cells, which are vital for the protection of the skin against the damaging effects of exposure to U.V light, are the ones responsible for the production of melanin, a pigment that will give the skin, and hair, their characteristic color.
Melanocytes originate germinally from the neural crest and they can be easily found on the matrix of hair an also on the basal portion of the skin layers, on the epidermis.
A person´s darkened skin color can be the result of prolongued exposure to sun radiation, which will lead melanocytes to produce melanin in increased amounts, or it can also be because of an uncharacteristic reproduction of melanocytes themselves, for various reasons.
2. Beginning with the superior vena cava, trace the path followed by a red blood cell as it passes into and through the heart, to the lungs, back to and through the heart, and to the rest of the body. Name each heart chamber, valve, and large blood vessel in the pathway.
Answer:
BLOOD PATHWAY:
Body > superior and inferior vena cava > right atrium > tricuspid valve > right ventricle > pulmonary semilunar valve > pulmonary artery > lungs > pulmonary vien > left ventricle > bicuspid/mitral valve> left ventricle > Aortic semilunar valve > Aorta > Body
The pathway goes like this:
From the body (we don't say first because this is a cycle), unoxygenated blood collected goes to the heart via the INFERIOR and SUPERIOR VENA CAVA then it empties into the RIGHT ATRIUM from there it passess through a valve called TRICUSPID valve, which prevents backflow of blood to the right atrium. The blood goes to our first pumping chamber, RIGHT VENTRICLE. The right ventricle pumps the blood through the PULMONARY SEMILUNAR VALVE which leads to the PULMONARY ARTERIES, which happens to be the only arteries that carry unoxygenated blood. From there it goes to the lungs to pick up oxygen and rid itself of carbon dioxide. The blood then goes back into the heart via the PULMONARY VEINS and like the latter, they are the only veins that carry oxygenated blood.
The blood then goes back into the heart, emptying into the LEFT ATRIUM. From there it goes through the BICUSPID VALVE or MITRAL VALVE and to the last and thickest pumping chamber, the LEFT VENTRICLE. The left ventricle pumps the blood through the AORTIC SEMILUNAR VALVE which opens out to the AORTA.
And at last, it goes back to your body.
Blood flows from the superior vena cava into the right atrium of the heart, from there it flows through the tricuspid valve to the right ventricle, and then to the lungs. After gas exchange in the lungs, blood returns to the heart's left atrium and then into the left ventricle through the mitral valve. Finally, the blood is pumped from the left ventricle through the aortic valve to the aorta and to the rest of the body.
Explanation:The pathway of a red blood cell as it passes into and through the heart, to the lungs, back to the heart, and to the body starts in the superior vena cava. From the superior vena cava, blood enters the right atrium of the heart, passes through the tricuspid valve, and moves into the right ventricle. The blood is then pumped through the pulmonary valve into the pulmonary arteries, which lead to the lungs. Here, gas exchange occurs, oxygenating the blood. The oxygen-rich blood then returns to the heart through the pulmonary veins, entering the left atrium. It then goes through the mitral valve into the left ventricle. From the left ventricle, blood is pumped through the aortic valve into the aorta, the body's main artery. The blood is then transported to the rest of the body through a system of arteries, arterioles, and capillaries. Once the oxygen is delivered, the blood returns back to the heart via capillaries, venules, veins and finally the superior and inferior vena cava, ready to begin the journey again. Following this path, one can understand the flow of blood in the pulmonary and systemic circuits.
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A person with blood type O would ________.
A. lack both antigens A and B on their erythrocytes.
B. are universal recipients.
C. possess neither anti-A nor anti-B antibodies circulating in their blood plasma.
D. possess both A and B on their erythrocytes.
Answer:
A. lack both antigens A and B on their erythrocytes.
Explanation:
A person with blood type O would lack both antigens A and B on their erythrocytes.
All collagen family members consist of _____ chains arranged in a _______.
Answer: All collagen family members consist of peptide chains arranged in a parallel chain to an axis, forming the collagen fibers.
Explanation:
The term “collagen” is used to denote a family of 27 isoforms proteins found in the connective tissues of the body. It is the most important compound in the connective tissue and is an important structural element in multicellular organisms. It contains peptide chains amino acids glycine, proline, lysine, hydroxylysine, hydroxyproline, and alanine. These chains are organized in parallel to an axis, forming the collagen fibers, that provides strength and elasticity to the structure. The collagen molecule has 280 nm of length, with molecular weight 300,000 Da, stabilized by hydrogen bridges and intermolecular bonds.
Different types of normal tissues in the human body have different mitotic indices. From the following list, which normal tissues would you expect to have the highest mitotic index: muscle, skin, kidney, or lung? Explain your answer.
Answer:
Skin
Explanation:
The tissues with high mitotic index have a number of cells undergoing mitosis. Among the given options, cells of skin exhibit the highest mitotic index. The skin forms the outer most covering of the body surface. Its cells are exposed to various agents of wear and tear.
To replace the damaged cells, the cells of the skin undergo mitosis. So, skin exhibits the highest mitotic index.
The skin tissue would have the highest mitotic index among the tissues listed. This is because skin is constantly exposed to environmental damage and needs frequent cell replacement, which requires a high rate of cell division. Muscle, kidney, and lung tissues generally have lower mitotic indices due to less frequent cell division.
Explanation:The term mitotic index refers to the ratio of cells in a population undergoing mitosis. It is often used as an indication of the proliferative activity of the cell population. Mitosis is most frequently found in tissues that are dividing and growing or being replaced. Among the tissues listed, skin tissue would have the highest mitotic index.
This is because the skin is constantly being exposed to the external environment and is thus often damaged and needs to be replaced. The dead or damaged skin cells on the surface are frequently shed and need to be replaced by newer cells from the lower layers. This process requires a continuous cycle of cell division, hence a high mitotic index.
In contrast, the other tissues listed, such as muscle, kidney, and lung tissues, typically have lower mitotic indices. These tissues rarely undergo cell division, except for repairing damage or during growth. Thus, their mitotic indices are significantly lower than the skin's.
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2. Why can you say that males determine the sex of their children?
Since males have two X chromosomes, whichever one is passed along to their offspring will determine the sex.
Male chromosomes are inherited preferentially over female chromosomes.
Males will either contribute an X or a Y chromosome, whereas females will always contribute an X chromosome.
Y chromosomes are dominant; X chromosomes are recessive.
All of the above.
Answer:
Male will either contribute an X or Y chromosome....
For the average human, blood lactate:
a. begins to accumulate significantly at a point that is about 55-65% of Vo2 max
b. begins to accumulate significantly only when the Vo2 max is reached
c.can be used as an energy fuel by the heart and skeletal muscles
d. a and c
Answer: a. begins to accumulate significantly at a point that is about 55-65% of Vo2 max
Explanation:
Lactate is produced in the body after the burning of glucose (glycolysis), to supply energy without the presence of oxygen (lactic anaerobic metabolism). In long-term physical activities, oxygen supply is not always sufficient. The organism seeks this energy in alternative sources, producing lactate. For the average human, blood lactate begins to accumulate significantly at a point that is about 55-65% of Vo2 max. The accumulation of this substance in the muscles can generate a hyperacidity, which causes pain and discomfort soon after exercise. Thus, the determination of lactate blood concentration allows indirect evaluation of the metabolic acidosis of the exercise, being one of the diagnostic tools used by Exercise Physiology.
What is a goblet cell? What is secreted by a goblet cell?
Explanation:
Goblet cells can be found in numerous numbers distributed among the columnar epithelial cells throughout the gastrointestinal tract. They are specialized in producing and secreting a high molecular weight mucopolysaccharide known as mucins. The columnar epithelial cells of the respiratory airways contain cilia on their apical surface (the surface facing the lumen, or cavity), which move the mucus toward the throat.
A goblet cell is a type of unicellular gland found in the columnar epithelium in the body. Their main function is to produce and secrete mucus, which helps to protect the body's interior surfaces and plays a key role in trapping unwanted particles and microorganisms.
Explanation:A goblet cell is a unicellular gland that is typically found in the columnar epithelium lining of organs such as the small intestine and the respiratory tract. These cells are named for their distinctive shape, which is reminiscent of a goblet or wineglass.
The primary role of goblet cells is to produce and secrete mucus, a thick, slippery substance that serves various protective and lubricative functions in the body. The mucus secreted by goblet cells helps to protect the body's interior surfaces, facilitating the movement of materials and also trapping unwanted particles, effectively playing an integral part in immune responses. For example, goblet cells in the intestinal epithelium secrete mucus into the digestive tract lumen and those in the respiratory tract secrete mucus that traps incoming microorganisms and particles.
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6. Before transferring sperm to the female during mating, the males of some species of beetles use their copulatory organs to remove the sperm of other males. In cases in which a female mated first with a male of a different species, the male of her own species is particularly adept at removing the other male’s sperm. This is an example of _______ isolation.
a. geographical
b. temporal
c. mechanical
d. postzygotic
e. precoital
Answer: Mechanical Isolation
Explanation:
Mechanical isolation is a type of barrier that prevents the species that are closely related from mating with each other.
It is used in case of plants and animals(here beetles) in which the without compatible sex organs individual of different species will not be able to mate and produce offspring.
Thus, the correct answer is option C
When you drive down the street listening to your car’s radio, you may not think about the fact that the music is received by the radio’s antenna. Which part of the human neuron serves the same purpose as an antenna – that is, receiving information?
Your answer would be dendrites.
Dendrites look like branches coming off of the main body of the neuron. They receive electrical signals from axons, and then transmit them to the rest of the cell body.
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In what ways are humans like the other primates? In what ways are we unique?
Answer:
In what ways are humans like the other primates?
Primates and humans have taking hands and feet that let them hang from branches, grab food, and, in some primates, use tools. The first digit in many primates and humans are opposable and at least some, if not all, of the digits, have nails.
Unlike the eyes of shrews and squirrels, which sit on each side of the head so that the two fields of vision do not overlap, the eyes of primates and humans are shifted forward to the front of the face. This produces an overlapping binocular vision that lets the brain judge distance precisely—important to an animal moving through the trees.
In what ways are we unique?
The first hominids were australopithecines. The ability to walk upright on two legs marks the beginning of hominid evolution. Humans diverge from apes in numerous areas of anatomy related to bipedal locomotion. Because humans walk on two legs, their vertebral column is more curved than an ape’s, and the human spinal cord exits from the bottom rather than the back of the skull. The human pelvis has become broader and more bowl-shaped, with the bones curving forward to center the weight of the body over the legs.
A controlled experiment _____. is repeated many times to ensure that the results are accurate includes at least two groups, one of which does not receive the experimental treatment includes at least two groups, one differing from the other by two or more variables includes one group for which the scientist controls all variables...........biology
A controlled experiment in biology includes at least two groups, one of which does not receive the experimental treatment. It is repeated many times to ensure accurate results.
Explanation:In biology, a controlled experiment includes at least two groups, one of which does not receive the experimental treatment. This helps to determine the effects of the treatment compared to a control group. It is important to repeat the experiment many times to ensure accurate results and account for any variability.
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A controlled experiment in biology uses at least two groups; an experimental group and a controlled group. The only variable that differs between these groups is the one being tested. Examining the results across these groups allows researchers to assess the impact of this variable.
Explanation:
A controlled experiment is a vital concept in scientific research. It involves at least two groups: the experimental group and the control group. The experimental group receives the experimental manipulation, which is the treatment or variable being tested, while the control group does not. The purpose of these two groups is to isolate and examine the effects of one variable.
In a controlled experiment, the one and only variable that differs between these groups is the independent variable, i.e., the treatment being tested. Observing changes in the dependent variable across these groups then allows the researcher to draw conclusions about the influence of the independent variable. Thus, if the results of the experiment reveal significant differences between the two groups, this is attributed to the impact of the independent variable.
These experiments can be lab-based or field-based depending on the nature of the study. Careful design, including random selection and assignment, along with proper ethical considerations are crucial for such experiments to yield reliable and accurate data.
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Radioactive amino acids incorporated into the proteins were rejected into the retina of a rabbit. After measuring the radioactivity and distance after a couple of experiments, two moving peaks were observed. The first peak moved 0.5-2 mm/day indicating that those are _________________ proteins which took up the radioactive AA whereas the second peak moved 200-400 mm/day indicating that those are _________________ proteins which took up the radioactive AA.
a. cytoplasmic, transmembrane
b. secreted, transmembrane
c. transmembrane, cytoplasmic
Answer:
cytoplasmic, transmembrane
Explanation:
Pulse chase experiment is an important technique used to analyze the cellular process by labeling the cells with radioactive compound.
The radioactive amino acids is injected into the rabbit's retina. Two different moving peaks are observed during the experiment. The first peak moved at 0.5-2 mm/day and second peak at 200-400 mm/day. These peaks are observed due to difference in the synthesis and transport rate of the protein. Cytoplasmic protein has slow transport and sorting rate, indicates the first peak. The second peak corresponds to transmembrane protein.
Thus, the correct answer is option (a).
Proteins are broken down into ____________ ; carbohydrates into ____________ ; and fats (triglycerides) into ____________ . The smaller sized molecules allow for transport across the mucosal membrane.
Answer:
Proteins are broken down into amino acids, carbohydrates into simple sugars and fats into simple fatty acids.
Explanation:
Digestion may be defined as the process of breakdown of biomolecules into simpler substances with the help of enzymes and digestive juices.
The process of breakdown of carbohydrates starts in the mouth with the help of enzyme salivary amylase. Carbohydrates are broken into simple sugars and later absorbed by the body. The absorption and digestion of proteins is completed into the small intestine. Proteins are broken converted into amino acids after complete digestion. Lipase enzyme breaks down the fat into simple fatty acids and glycerol.
In digestion, proteins, carbohydrates, and fats are broken down into amino acids, monosaccharides, and glycerol and fatty acids respectively, which are then absorbed by the body.
Explanation:During the process of digestion, different types of macromolecules are broken down into their smaller components for absorption. Proteins are broken down into amino acids, carbohydrates into monosaccharides, such as glucose, and fats, or triglycerides, are broken down into glycerol and fatty acids. This breakdown is crucial for the molecules to be small enough to be transported across the mucosal membrane and be utilized by the body.
The complex carbohydrates are first acted upon by enzymes like amylase, which break them down into simpler sugars, or monosaccharides. Proteins are degraded into amino acids by enzymes such as trypsin, pepsin, and peptidase. Lipids are broken down by lipase into glycerol and fatty acids. The smaller molecules resulting from the actions of these enzymes can then be absorbed by the cells lining the small intestine and used for various bodily functions including energy production, cellular repair, and growth.
If two populations are merged, each with different frequencies of an allele at a locus, and random mating occurs immediately, how long will it take to achieve a Hardy–Weinberg equilibrium in the new population?
One generation
Unpredictable
Ten generations
Depends on the allele frequencies
Never
Answer:
I think its one generation
Answer:
One generation
Explanation:
If two populations are merged, each with different frequencies of one allele at one location, and random mating occurs immediately; after a generation this population will be in Hardy-Weinberg equilibrium, as there were no evolutionary processes within the population and mating occurred entirely at random.
The Hardy-Weinberg equilibrium states that in a population in which crossings occur at random and over which there are no evolutionary factors, gene and genotypic frequencies remain constant over the generations.
The importance of the Hardy-Weinberg Balance for natural populations lies in the fact that it establishes a model for gene behavior. Thus, it is possible to stimulate gene frequencies and genotypic frequencies over generations and compare them with those obtained in practice. If the observed values are significantly different from the expected values, it can be concluded that evolutionary factors are acting on this population and that it is evolving. If the values do not differ significantly, it can be concluded that the population is in equilibrium and therefore not evolving.
Sulfonamides interfere with __________. Sulfonamides interfere with __________. anaerobic metabolism in protozoa protein synthesis in helminths folic acid synthesis in bacteria protein synthesis in fungi
Answer: Sulfonamides interfere with folic acid synthesis in bacteria.
Explanation:
Sulfanilamide and other Sulfonamides are capable of inhibiting a variety of bacteria, interfering with a particular biochemical reaction (synthesis of the folic acid) which is essential for their survival. Sulfonamides are primarily used to treat urinary infections and for the treatment of otitis, bronchitis, sinusitis, and Pneumocystis pneumonia; It is used in combination with trimethoprim. Sulfonamides derivatives exert a wide range of antimicrobial activity against Gram-positive and Gram-negative bacteria.
The blood speed in a normal segment of a horizontal artery is 0.140 m/s. An abnormal segment of the artery is narrowed down by an arteriosclerotic plaque to one-fourth the normal cross-sectional area. What is the difference in blood pressures between the normal and constricted segments of the artery?
Answer:
[tex]96[/tex]Pa
Explanation:
Let "n" represents the normal flow condition and "a" represents the abnormal flow condition.
As per continuity equation -
[tex]v_{n}*A_{n}= v_{a}*A_{a}[/tex]----------- Eq (1)
Where "v" represents the velocity and "a" represents the area of artery
Given-
[tex]A_a=\frac{A_n}{4}[/tex]
Substituting the above relation in equation (1), we get -
[tex]v_a = \frac{v_n*A_n}{A_a}\\ v_a= 4v_n\\[/tex]
As per Bernoulli's theorem, we know that -
[tex]P_a-P_n= \frac{1}{2}pv_a^2-\frac{1}{2}pv_n^2\\P_a-P_n=\frac{1}{2}p[\frac{v_a*A_a}{A_n} ]^2\\P_a-P_n=\frac{1}{2}pv_n^2[16-1]\\P_a-P_n=\frac{1}{2}*1060*(0.11)^2*15\\P_a-P_n=96[/tex]Pa
The blood pressure difference between the normal and constricted segments of the artery can be calculated using Bernoulli's equation. As the cross-sectional area is reduced in the constricted segment, the blood speed increases and the pressure decreases. The difference in blood pressures can be determined by comparing the pressure energy per unit volume in the two segments.
Explanation:The blood pressure difference between the normal and constricted segments of the artery can be calculated using Bernoulli's equation, which states that the sum of pressure energy, kinetic energy, and potential energy per unit volume is constant along a streamline in an ideal fluid flow. In this case, as the cross-sectional area of the artery is reduced to one-fourth in the constricted segment, the blood speed increases. As a result, the pressure in the constricted segment decreases due to the conservation of energy. The difference in blood pressures between the normal and constricted segments can be determined by comparing the pressure energy per unit volume in the two segments.
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The NADH coenzyme enters the electron transport chain:
A- anywhere in the chain
B- for ATPase
C- through the membrane
D- in the first dehydrogenase
Answer: C- through the membrane
Explanation:
The molecules of NADH and FADH2 resulting from the of Krebs (by the reduction, respectively, of NAD + and FAD) carriers of electrons and protons (e- and H +), are oxidized in the final reactions of cellular respiration, and the electrons and protons are picked up by oxygen, the final acceptor. Electron transport occurs in the intermembrane space. The electron transport chain contains 3 large protein complexes in the inner membrane of mitochondria; a small protein - cytochrome c; and a non-protein component - ubiquinone (Q).
A plant grown from a [round, yellow] seed is crossed with a plant grown from a [wrinkled, yellow] seed. This cross produces four progeny types in the F1: [round, yellow], [wrinkled, yellow], [round, green], and [wrinkled, green]. Use this information to deduce the genotypes of the parent plants.
Answer:
Parent Genotypes: RrYy x rrYy
Explanation:
"Because the cross produces green progeny (and both parents are yellow), both parents must be Yy: If either parent were YY, only yellow progeny would result.
The cross also produces wrinkled progeny, so the [round, yellow] parent must be heterozygous (Rr): If it were RR, all of the progeny would be Rr and have a round phenotype." - Mastering Genetics
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A plant grown from a [round, yellow] seed is crossed with a plant grown from a [wrinkled, yellow] seed. This is called parent genotype.
What is genotype?The type of variant present at a specific locus (i.e., region) in the genome is scored by what is known as a genotype. Symbols can be used to symbolize it.
The actual DNA sequence, such as CC, CT, or TT, can also serve as a representation of a genotype. In a single experiment, the genotypes at millions of sites in a genome can be determined using DNA sequencing and other techniques.
The cross also produces wrinkled progeny, so the [round, yellow] parent must be heterozygous (Rr): If it were RR, all of the progeny would be Rr and have a round phenotype." - Mastering Genetics.
Therefore, A plant grown from a [round, yellow] seed is crossed with a plant grown from a [wrinkled, yellow] seed. This is called parent genotype.
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Explain how chemotherapy aggravates the effects of leukemia.
Answer: Chemotherapy kills the leukemia cells, but releases the content of the cell into the bloodstream which cannot be filtered at once by the kidney.
Explanation: Chemotherapy can be defined as the use of drugs to treat cancer. The drugs that is given in chemotherapy flows through the bloodstream to reach all over the body.
This treatment method is only used for the people suffering from acute lymphocytic leukemia. Because of its potential side effect it cannot be used for the person who is already sick.
The chemo cells are killed by leukemia cell and the contents are released into the blood stream which are not filtered by the kidney at once. Excess amount of these substances in blood can adversely affect the nervous system and heart.
This is how the chemotherapy enhances the effects of leukemia.
Chemotherapy can worsen leukemia by damaging normal cells, reducing white blood cell count, and increasing the risk of secondary cancers.
Chemotherapy aggravates the effects of leukemia by not only targeting cancer cells but also damaging normal rapidly dividing cells like those in the bone marrow, leading to a decrease in white blood cells. This can result in secondary immunodeficiency, making the patient more susceptible to infections. Additionally, chemotherapy drugs that damage DNA increase the risk of developing secondary cancers, including leukemia.
A antimicrobial method that reduced a population from 10000 to 100 cells in 10 minutes has a decimal reduction time of _______.
Answer:
Decimal reduction time [tex]= 990[/tex] cells per minute
Explanation:
Given -
Initial population of cells [tex]=10000[/tex]
Final population of cells [tex]=100[/tex]
Total change in population of cells is equal to final population of cells minus the initial population of cells.
Total change in population of cells [tex]= 10000-100\\= 9900\\[/tex]
Total time taken by cell to reduce [tex]= 10[/tex] minutes
Decimal reduction time
[tex]= \frac{9900}{10} \\= 990[/tex] cells per minute
17. In chickens, some varieties have feathered shanks (legs), but others do not. In a cross between a Black Langhans (feathered shanks) and Buff Rocks (unfeathered shanks), the shanks of the F1 generation are all feathered. When the F1 generation is crossed, the F2 generation contains chickens with feathered shanks to unfeathered shanks in a ratio of 15:1. Suggest an explanation for this result.
Answer:
Feathered shanks is an example of duplicate dominant epistasis and gives F2 phenotype ratio 15:1.
Explanation:
Presence of feathered shanks in chickens is an example of duplicate dominant epistasis. The trait is controlled by two dominant genes (A and B). Presence of at least one copy of any of these two dominant alleles results in feathered shanks. The homozygous recessive genotype (aabb) exhibits "unfeathered shanks".
Genotype of parents: Black Langhans (feathered shanks; AABB) and Buff Rocks (unfeathered shanks; aabb). F1 has genotype AaBb and crossing the F1 gives F2 chickens with feathered shanks to unfeathered shanks in a ratio of 15:1.
Final answer:
The observed 15:1 ratio of feathered to unfeathered shanks in the F2 generation of chickens suggests a gene interaction between two dominant genes. The only recessive phenotype results from having both recessive alleles for the two genes, which occurs in 1 out of 16 offspring.
Explanation:
The question is asking for an explanation of the genetic inheritance pattern observed in chickens with regards to feathered shanks. The F1 generation resulting from a cross between a Black Langhans (feathered shanks) and Buff Rocks (unfeathered shanks) are all feathered, indicating that feathered shanks are a dominant trait. However, when these F1 chickens are crossed, the F2 generation shows a 15:1 ratio of feathered to unfeathered. This ratio is much greater than the typical 3:1 ratio seen in a simple Mendelian monohybrid cross, suggesting that the inheritance of the trait is not controlled by a single gene.
A likely explanation is that the feathered shanks trait is controlled by two dominant genes that are interacting in such a way that having one or both genes results in the feathered phenotype. This is an example of gene interaction or epistasis, where different genes contribute to the expression of a single trait. The 15:1 ratio suggests that when crossing two F1 heterozygotes (RrSs), the only way to get unfeathered shanks (the recessive phenotype) is if the offspring inherits two recessive alleles for both genes (rrss), which occurs only in 1 out of 16 cases.
A ship is able to float on water because it has a higher density than the water.
Answer:
False
Explanation:
the boat has a lower density therefore allowing it to float
Answer:
False.
Explanation:
The ship is capable of floating because its average density (considering the steel part and the air filled part) is less than the water density. Moreover, it is in equilibrium, partially immersed and subject to the action of two forces of the same and opposite modulus, the weight P and the thrust E, exerted by water.
But the stability of the ship does not depend on it alone. It also depends on the point of application of these forces. The weight force is applied to the center of gravity (CG), which is fixed, and the thrust is applied to the center of thrust (EC), which is variable.
What valve is located between the left atrium and left ventricle?
the mitral valve, between the left atrium and left ventricle; and. the aortic valve, between the left ventricle and the aorta.
Which valve is between the left atrium and the ventricle?Mitral valve: This valve has two leaflets. They allow blood to flow from the lungs to the left atrium. And they prevent regurgitation from the left ventricle to the left atrium.
Usually, mitral valve prolapse is not life-threatening and does not require treatment or lifestyle changes. However, some people may need medication or surgery, especially if escape causes severe belching. Another name used to describe mitral valve prolapse are Barlow Syndrome.
Mitral valve disease occurs when the mitral valve is not functioning properly and allows blood to flow back into the left atrium. As a result, the heart does not pump enough blood from the left ventricle to supply the body with oxygen-rich blood.
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1) Rigor mortis occurs after a person dies because muscle cells are no longer supplied with ATP. This causes the muscles to become rigid and stuck in position. Based on your knowledge of muscle contraction, why would muscles become rigid, rather than limp, after death?
2) The term fibrillation refers to an irregular, ineffective heartbeat. Do you think ventricular fibrillation is more or less serious than atrial fibrillation in a human? Explain your reasoning.
Answer:
1.)Rigor mortis, the stiffening of a body several hours after death, arises from a combination of two of the oldest definitions of death – cessation of the heartbeat and cessation of breathing. Once either of these essential functions stops, the cells of the body lose their oxygen supply and can no longer perform aerobic respiration.
Immediately after death, the muscles of the body contract in the same manner as they do when the person is alive. Muscle is formed of bundles of long and narrow cells that can span the entire muscle’s length.
In the resting state, these cells build up the electric potential across their membrane by actively pumping out calcium ions. Upon receiving a signal from a neuron, the muscle cells open the calcium channels in their cell membrane, and the calcium ions rush in due to the voltage difference between the inside and outside of the cell.
2.) I think VFib (ventricular fibrillation) is more serious due to the fact that AFib is not normally life threatening and not nearly as much as VFib and the ventricles pour out all to blood to the body making it extremely vital
Rigor mortis occurs because ATP is needed for muscles to relax, and when there's no more ATP after death, muscles remain in a contracted state. Ventricular fibrillation is more serious than atrial fibrillation due to the vital role of ventricles in pumping oxygenated blood to the body.
Explanation:Rigor mortis occurs because the processes that control muscle relaxation are ATP-dependent. Normally, after a muscle contracts, ATP binds to the myosin head allowing it to release from actin, resulting in muscle relaxation. However, after death, when ATP supply stops, the myosin heads can't detach from actin, causing a sustained muscle contraction, or 'rigidity'.
As for the distinction between atrial fibrillation and ventricular fibrillation in humans, ventricular fibrillation is generally considered more dangerous. This is because the ventricles are the main pumps of the heart, delivering oxygenated blood to the body. If they begin to fibrillate, blood is not effectively pushed out of the heart, which can quickly lead to cardiac arrest and death if not immediately treated.
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Defecation depends on
a. distention of the rectal wall
b. sensory impulses to the sacral spinal cord
c. motor impulses back to the colon
d. all of the above must happen for defecation to occur
Answer: the correct answer is d. all of the above must happen for defecation to occur.
Explanation:
In response to the distention of the rectal wall, the receptors send sensory nerve impulses to the sacral spinal cord. Motor impulses from the cord travel along parasympathetic nerves back to the descending colon, sigmoid colon, rectum, and anus. The resulting contraction of the longitudinal rectal muscles shortens the rectum, thereby increasing the pressure within it. This then opens the internal sphincter.
Water moves via osmosis _________. a) from an area with a high concentration of water to one of lower concentration b) water does not move from an area with a low concentration of water to one of higher concentration c) from an area with a high concentration of other solutes to a lower one throughout the cytoplasm
Answer:
correct option a
Explanation:
movement of water molecule from an area of higher concentration to an area of lower concentration
How does CRA-cAMP positively regulate the lac operon?
Answer:
The CRA-cAMP complex increases the rate of expression of lac operon when glucose is absent and lactose is present as nutrient.
Explanation:
CRP is the catabolite gene activator protein that forms a complex with cAMP. The CRP-cAMP complex facilitates the binding of RNA polymerase to the promoter region of the lac operon. This robust binding as stimulated by CRP-cAMP complex is followed by the formation of open complex and initiation of gene expression.
Hence, the CRP-cAMP complex positively regulates the lac operon and increases its expression when glucose is not present.
The maintenance of homeostasis a. involves using material culture to make living possible in certain settings. b. involves the study of populations in their natural environments. c. involves the replication of environmental conditions and human responses to those conditions. d. is a key feature of most levels of any organism’s biology.
Answer: C. Involves the replication of environmental conditions and human responces to those conditions
Explanation:
The maintenance of homeostasis is a key feature of most levels of any organism’s biology.
In biology, homeostasis is the state of steady internal, physical, chemical, and social conditions maintained by living systems.This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits .
Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium, and calcium ions, as well as the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of these variables is controlled by one or more regulators or homeostatic mechanisms, which together maintain life.It is a key feature of most levels of any organism’s biology.
Thus, option D is correct.
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Which of the following processes randomly effect (i.e. you cannot calculate the precise end result) the change in allele frequencies over time? (It is not all of them)
Sexual Selection
Natural Selection
Genetic Drift
Gene Flow
Mutation
Answer:
Mutations and Genetic Drift
Explanation:
A mutation refers to the random changes in the genome of the organisms. Being a random event, it is not possible to calculate the effect of mutations on the allele frequency of a population.
Genetic drift refers to changes in the allele frequency by chance event alone. Since the occurrence of chance events can not be predicted, the resultant changes in the allele frequency of the population can not be calculated.
List, in order, all the structures the filtrate must flow through to get from the glomerulus to the outside of the body.
Answer:
The glomerulus is a tiny structure which is made up of capillary blood vessels which filters the waste product from the blood to form urine.
The glomerulus makes the functional unit called the nephron. Each nephron is made up of structures through which urine passes in the following way :
1. Glomerular capsule (Bowman's capsule)- capsule surrounding the glomerulus where fluid and solutes are filtered out of the blood.
2. Proximal Convoluted Tubule (PCT) - tube where water and salt reabsorption takes place.
3. The Loop of Henle- U-shaped tube which transfers the fluid from the proximal tubule to the distal tubule.
4. Distal Convoluted Tubule (DCT)- tubule which is the final site of reabsorption in the nephron.
5. Collecting duct - duct which transfers the urine to the ureter.
6. Ureter- thin tube-like structures of 8 to 10 inches long which force urine to away from the kidney.
7. Urinary bladder- hollow, balloon-shaped organ stores urine for 3-5 hours.