Answer:
the plates of the lithosphere move (or float) on this hot, malleable semi liquid zone in the upper mantle, directly underneath the lithosphere
Explanation:
Lithosphere is the outermost layer of earth surface which contains crust and uppermost solid mantle. Tectonic plates are subdivision of lithosphere where tectonic activities take place. Tectonic activities often occur in Lithosphere which affects the structure of this layer by changing the landscape on earth surface. The Lithosphere is the layer where soil forming process takes place. The lithosphere influences temperature difference on earth when it reacts with the other layers called atmosphere, hydrosphere and cryosphere.The lithosphere plates move on the asthenosphere in the upper mantle, a process known as plate tectonics. The movement is facilitated by slow convection of the mantle. When plates come together, one plate is subducted beneath another, a process occurring in subduction zones.
Explanation:The plates of the lithosphere move (or float) on the hot, malleable asthenosphere zone in the upper mantle, directly underneath the lithosphere. This is known as plate tectonics.
Earth's crust and upper mantle are divided into about a dozen tectonic plates that fit together like the pieces of a jigsaw puzzle. The power to move the plates is provided by slow convection of the mantle, a process by which heat escapes from the interior through the upward flow of warmer material and the slow sinking of cooler material.
As new crust is added to Earth, the old crust must go somewhere. When two plates come together, one plate is often forced beneath another in what is called a subduction zone. The subducted plate is forced down into regions of high pressure and temperature, eventually melting several hundred kilometers below the surface. Its material is recycled into a downward-flowing convection current, ultimately balancing the flow of material that rises along rift zones.
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ATP is required for the contraction of a sarcomere and thus a muscle fiber. At death, the production of ATP ceases and the ATP stores in a cell are quickly used up. The cell's membranes become permeable to calcium and calcium enters the cytosol of the cell and attaches to troponin, removing tropomyosin from the actin active sites. Myosin attaches to the actin active sites and the muscle contracts for several cycles until the ATP stores are depleted. The muscles are then unable to relax. This postmortem contraction of the muscles is called rigor mortis. Rigor mortis is ultimately caused by a lack of ATP that would, if present, (1) allow calcium to be pumped out of the cytosol and into the sarcoplasmic reticulum and (2) __________.
Answer:
2. Break down the myosin-actin bridge and cause relaxation. ATP replaces ADP to cause this relaxation. ADP causes the continuous binding of action to myosin thus preventing relaxation. It's action continues in rigor motifs. But ATP presence helps to breaks this link and enhance Relaxation
_________________ was the father of scientific management. Select one: a. Henry Gantt b. Elton Mayo c. Frank Gilbreth d. Frederick Taylor
During which phase would penicillin, an antibiotic that inhibits cell-wall synthesis, be most effective?
Answer:
Explanation:
I would need help to
Penicillin, an antibiotic that inhibits cell-wall synthesis, would be most effective during the bacterial cell's growth and division phase, which is known as the "log" or "exponential" phase.
During this phase, bacteria actively replicate and grow, leading to the synthesis of new cell wall material to accommodate the increasing cell size. Penicillin targets the enzymes responsible for building the bacterial cell wall by inhibiting peptidoglycan cross-linking.
In the log phase, bacteria are most vulnerable to antibiotics that disrupt cell wall synthesis because they are actively producing and modifying their cell walls. When penicillin is introduced during this phase, it interferes with the construction of the cell wall, causing the bacteria to weaken and eventually burst due to the osmotic pressure imbalance. Other phases, like the stationary phase or the lag phase, have reduced metabolic activity and may exhibit antibiotic resistance mechanisms, making penicillin less effective. Therefore, targeting the log phase ensures the highest efficacy in combating bacterial infections with penicillin.
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A vestigial-winged, hairy male is crossed with a wild-type female, homozygous at both genes. This F1 generation is crossed to produce the F2 generation. Which of the following are accurate expectations regarding the F1 or F2 generations resulting from this cross? Choose all reasonable answers. Please draw the full 4x4 Punnett Square to answer this question.a.The expected proportion of F2 individuals which are homozygous recessive at both genes is 1/16b.Most of the F2 generation will have the normal phenotypes for both genesc.The expected proportion of F2 individuals with at least one recessive phenotype (either hairy or vestigial wings) is 8/16d.All of the F1 generation will have the normal phenotypes for both genese.There will be no homozygous individuals in the F1 generation
Answer:
The expected proportion of F2 individuals which are homozygous recessive at both genes is 1/16
All of the F1 generation will have the normal phenotypes for both genes
There will be no homozygous individuals in the F1 generation
Most of the F2 generation will have the normal phenotypes for both genes
Explanation:
A winged hairy male is crossed with a wild type female which is homozygous
Let the allele for vestigial trait be v
allele for wild trait be w
allele for hairy trait be h
Allele for non hairy be n
The genotype of parents would be
vvhh * wwnn
Thus in F1 generation all the offsrping will have normal phenotypes for both genes
In F2 generation
vwnh * vwnh
Out of 16 offspring only one wil be homozygous recessive i,e
wwnn
Rest all 15 will have normal phenotypes.
Hence, the correct answer is
The expected proportion of F2 individuals which are homozygous recessive at both genes is 1/16
All of the F1 generation will have the normal phenotypes for both genes
There will be no homozygous individuals in the F1 generation
Most of the F2 generation will have the normal phenotypes for both genes
When true-breeding or homozygous individuals that differ for a certain trait are crossed, all of the offspring will be heterozygotes for that trait. If these heterozygous offspring are self-crossed, the resulting F2 offspring will exhibit a ratio of three dominant to one recessive.
Explanation:When true-breeding or homozygous individuals that differ for a certain trait are crossed, all of the offspring will be heterozygotes for that trait. If the traits are inherited as dominant and recessive, the F1 offspring will all exhibit the same phenotype as the parent homozygous for the dominant trait. If these heterozygous offspring are self-crossed, the resulting F2 offspring will be equally likely to inherit gametes carrying the dominant or recessive trait, giving rise to offspring of which one quarter are homozygous dominant, half are heterozygous, and one quarter are homozygous recessive. Because homozygous dominant and heterozygous individuals are phenotypically identical, the observed traits in the F2 offspring will exhibit a ratio of three dominant to one recessive.
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A change in the responsiveness of the sensory system based on the average level of surrounding stimulation is called sensory _____.
Answer:
Sensory adaptation.
Explanation:
An exposure to constant or prolonged stimulus will slowly decrease our response.For example, when we rested our arm or hand on the table then the surface of the table will abruptly feel against our hand.Sensory adaptation helps us in daily life work by decreasing our response to constant stimulus that's why we give our attention to other environmental aspects. If our response will remain constant to prolonged stimulus then we can't detect new or important environmental aspects.Durkheim uses the term ______ to describe the disorientation and anxiety members of a society experience when they no longer have shared beliefs, values, and standards for conduct.
Answer:
Durkheim uses the term _anomie_ to describe the disorientation and anxiety members of a society experience when they no longer have shared beliefs, values, and standards for conduct.
Explanation:
David Émile Durkheim was a French sociologist who established the academic discipline of sociology which is commonly called as the principal architect of modern social science.
Anomie is
"the condition in which society provides little moral guidance to individuals". (See attached image for more clarity)
_______ is the study of how living things interact with each other and their environment
Answer:
EcologyExplanation:
Ecology is the study of biotic and abiotic factors of an ecosystem and the interactions between them.
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Ecology is the field of biology that deals with the interactions of living things with each other and their environment. It includes studying relationships between organisms and their surroundings and trying to understand the balance of life in the natural world.
Explanation:Ecology is the study of how living things interact with each other and their environment. This can involve examining the relationships and interactions between organisms, ranging from microscopic bacteria to large mammals, and their surroundings.
For example, ecologists might explore how tree populations impact the soil in a forest, how predators influence the behavior and population of their prey, or how pollution in a stream affects fish populations.
Overall, the goal of ecology is to understand the balance of life in the natural world.
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If a solute is moving through a phospholipid bilayer from an area of higher concentration to an area of lower concentration without the assistance of a protein, the manner of the transport must be:_____________
a. active transport
b. facilitated diffusion
c. simple diffusion
d. any of above, depending of the solute
e. solutes cannot cross phospholipids
Answer:
D because it depends on the size of solute
Explanation:
the particles moving from higher concentration to lower concentration
Collect a large array of colorful poisonous and non-poisonous mushrooms; also capture a mushroom-eating animal, such as frog. Present a hungry frog with a choice of mushrooms that have been dyed or painted a drab poisonous and non-poisonous mushrooms color versus others treated with a solution that is identical to the dye or paint used but uncolored. Record which mushrooms the animal eats. Repeat the test with one more animal and the same mushrooms.
Answer:
Many mushrooms are extremely colorful. One hypothesis is that the colors serve as a warning to prevent animals from eating mushrooms, much like the bright yellow and black stripes on wasps help to deter potential predators. Design an experiment capable of testing this hypothesis.
Explanation:
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Reaction rates
1. Suppose that the enzymes that catalyze the dehydration synthesis and hydrolysis reactions that build and break down organic compounds are sensitive to temperature. They operate most quickly at 30°C and become slower as the
2. At 20°C the enzyme that catalyzes the breakdown of polysaccharides functions at 1 reaction every 20 microseconds. If this enzyme catalyzes hydrolysis reactions of a very long polysaccharide molecule for 120 microseconds, into how many segments would this long polysaccharide be cut?
3. At 20°C the enzyme that catalyzes the synthesis of triglycerides functions at 1 reaction every 25 microseconds. If this enzyme catalyzes dehydration synthesis reactions for 450 microseconds, bonding fatty acids to glycerol, what is the maximum number of complete triglycerides that could be formed if no fatty acids were bonded to glycerol at the beginning of the reactions?
4. At 25°C the enzyme that catalyzes the hydrolysis of fatty acids from triglycerides functions at 1 reaction every 6 microseconds. If this enzyme catalyzes hydrolysis reactions for 96 microseconds, what is the maximum number of glycerol molecules that could be stripped of all of their fatty acids?
5. At 25°C the enzyme that catalyzes the hydrolysis of proteins functions at 1 reaction every 3 microseconds. If this enzyme catalyzes hydrolysis reactions of a very long polypeptide molecule for 27 microseconds, how many segments would the polypeptide be cut into?
Answer:
1. These enzymes operate most quickly at 30°C and become slower as the temperature is lower, and also when is higher.
2. Six fragments
3. Eighteen complete triglycerides
4. Sixteen glycerol molecules
5. Nine peptides
Explanation:
Question 1. it's known that at low temperatures the movement of particles is slower, and being 30°C the optimal temperature for these enzymes to work, below 30°C these enzymes will work slower. As these enzymes are also temperature-sensitive, at higher temperatures they tend to denature, and will work slower as temperature increases, and will stop when are totally denatured
For questions 2 to 5, we divide the reaction time in any of the group of enzymes involved in catalysis, between the 1 reaction time to obtain the performance ratio. That means number of fragments, segments, or molecules rendered after hydrolysis, or synthesis, in the respective given sort of catalysis.
Darker skin is more prevalent in high-UV areas. Dr. Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. On what evidence did she base this hypothesis?
Answer:
In environments with a high level of UV radiation darker skin protects against the harmful effects of UV radiation. According to the evidence, melanin is found in the upper layer of the skin human and absorbs UV radiation, which protects cells against the harmful effects of UV light. The genetic determine the type of melanin and the amount of melanin present in the cells of an individual. Ultraviolet radiation causes damages DNA and disrupts normal chemical reactions in cells. These processes are greatly mitigated by eumelanin that is abundant in dark skin. This condition also gives protection of folate metabolism against deficiencies caused by strong UV radiation, there is evidence from epidemiological studies that indicates an association between dark pigmentation and a lower rate of neural tube defects due to lower decomposition rates folate.
is not considered separate species because organisms of different breeds
can mate and produce fertile offspring.
Breed
Phenotype
Genotype
Fitness
Breed is not considered separate species because organisms of different breeds can mate and produce fertile offspring.
BreedExplanation:
A breed is a particular gathering of residential creatures having homogeneous appearance (phenotype), homogeneous conduct, and additionally different attributes that recognize it from different life forms of similar species. Comprehensively, various species can't interbreed and create solid, ripe posterity because of hindrances called systems of regenerative confinement.
These obstructions can be part into two classifications dependent on when they act: prezygotic and postzygotic. Generally, various species don't mate. Be that as it may, when they do, their posterity will be what are called cross breeds.
The body's internal environment is separated into compartments by barriers, including epithelial barriers, which may or may not allow for the movements of molecules from one compartment to the next. Which of the following terms most accurately describes these membranes? Semipermeable or selectively permeable
Answer:
Semi Permeable or selectively permeable
Explanation:
The multicellular organisms are made of the cells which contain the cell membrane. The cell membrane is composed of the phospholipids and the protein molecules which provides important properties to the membrane.
The membrane acts as the semi-permeable or selectively permeable membrane as it selects the molecules to be passed through it into and out of the cell.
In the given question, the property of the barrier which may or may not allow the molecules to pass through it is due to the selective nature of the membrane and thus the membrane is selectively membrane.
Thus, Semi-Permeable or selectively permeable is correct.
Which of the following parts of the nervous system would carry messages from one’s sore knee to the brain and spinal cord to alert the person to stop running and rest?
Answer:peripheral
somatic
Explanation:
somatic nervous system carried information from the joints,muscles, and skin to the spinal cord and brain
What is one way in which microbiologists can distinguish different bacteria that are similar in morphology and staining characteristics?
Answer: Biochemical testing
Explanation:
The biochemical testing is the method which is used to differentiate the bacterial species which is similar in morphology and staining conditions.
The microbiologists previously used gram staining but this technique is not much specific. Now the modern technique is biochemical testing which uses different testing method for more specific testing of the bacterial species.
Biochemical tests includes hydrogen sulfide production, citric acid utilization, methyl red, fermentation.
The larger value obtained when more glucose carriers were present corresponds to an increase in the rate of glucose transport. Explain why the rate increased. How well did the results compare with your prediction?
The rate of glucose transport increased due to the presence of more glucose carriers, which facilitated the transport of glucose into the cell. The results of the experiment should align with the prediction of increased transport rate.
Explanation:The rate of glucose transport increased when more glucose carriers were present because there were more transport proteins available to facilitate the movement of glucose across the cell membrane. These transport proteins, known as glucose carriers or glucose transporters, bind to glucose molecules and transport them into the cell.
By increasing the number of glucose carriers, the rate of glucose transport can be enhanced because there are more carriers available to transport glucose. This increases the efficiency of glucose uptake by the cell.
The results of the experiment should compare well with the prediction that an increase in the number of glucose carriers would lead to an increase in the rate of glucose transport. If more carriers were present, there would be a greater capacity for glucose transport, resulting in a higher rate of transport.
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Helen Fisher suggests that "through evolution humans have developed a set of neurochemicals that drive an 'evolutionary trajectory of loving'." Which of the following is a neurochemical that she sees as important in human sexuality?1. lactose2. dopamine3. pyrethrin4. melanin
Answer:
2. dopamine
Explanation:
Dopamine is one of the neurochemicals involved in the transmission of signals between the neurons of the brain. It is usually referred to as “the feel good” “happy” hormone that is released when stimulated by engaging in a pleasurable experience or activity. Dopamine controls the emotional and mental processes of humans. It is important in sexuality of human as it is responsible for the pleasurable feelings of satisfaction we experience.
6. Evolution explains both the unity and diversity of life. Explain how evolution can account for both why anoles and finches share certain traits and also why they differ. [2 pts]6. Evolution explains both the unity and diversity of life. Explain how evolution can account for both why anoles and finches share certain traits and also why they differ.
Evolutionary processes through natural selection acting on genetic variation explain the unity and diversity observed among species. Convergent evolution results in similar traits in different species, while divergent evolution leads to differences within groups that have common ancestors. Mutations drive the genetic variation that fuels these evolutionary processes.
Explanation:Evolutionary processes account for both the commonalities and differences between species such as anoles and finches. The theory of evolution is underpinned by the idea that all life is related and that modifications occur over time through natural selection acting on genetic variation.
On the one hand, convergent evolution explains how different species may develop similar traits as a result of adapting to similar environmental pressures. This leads to the unity of various life forms that look superficially similar due to similar selection pressures even though they might not be closely related genetically.
On the other hand, divergent evolution or adaptive radiation accounts for the diversity we see within groups of closely related organisms. Even though species like anoles and finches may share a common ancestor, the different environmental niches they occupy have pushed them to evolve distinct traits.
These differences highlight the adaptability and variation within species that result from the differential survival and reproduction of individuals with favorable traits. As environments change or as species spread into new habitats, natural selection favors different traits, leading to further diversification.
Variation within populations is driven by mutations, creating the genetic differences that are the raw material for evolution. The consistent yet various biological structures, behaviors, and adaptations seen in the living world all illustrate the balance of unity and diversity explained by evolutionary theory. It is this balance that has led to the rich tapestry of life we observe around us today.
1. Define isometric contraction and describe an example Isometric contraction occurs when the muscle is activated but held at a fixed length. An example would be the muscles of the leg when holding oneself in a squat position.
2. When the current reached the following stages, what proportion of fibers in the muscle were contracting?
a) at threshold
b) at the maximal stimulus
c) above the maximal stimulus
Answer:
1. Isometric contraction is best defined as a contraction that is not associated with any movement. It can be used by the therapist to increase strength and elasticity.
An example of an isometric contraction is carrying an object in front of you. The weight of the object would be pulling downward, but your hands and arms would be opposing the motion with equal force going upwards. Since your arms are neither raising or lowering, your biceps will be isometrically contracting.
2.
a. At threshold just a few muscle fibers are being recruited.
b. At the maximal stimulus is 100% of recruitable fibers are contracting.
c. Above maximal stimulus, the number of contracting fibers cannot increase.
Explanation:
Which vegetation type found in the Russian Federation represents a cold-resistant, coniferous forest?
Answer: Taiga.
Explanation:
Taiga is a very cold forest, it is found in the Northern Hemisphere below the South of the Arctic circle. It doubles as the driest and coldest forest in the world, it is also known as the boreal forest, composed of evergreen trees with scaled leafs and also leafs that bears cones and are needle like. This forest experience long winters.
The Taiga forest in Russia is about 5800km which happens to be the largest in the world, this area is completely covered by ice, even the soil in this region is permanently frozen.
The students in Ms. Hill's science class were investigating the properties of water. Juan dipped a finger in a beaker of water; Sally dipped her finger in a beaker of alcohol. They both streaked the lab bench with the liquids on their fingers and watched to see which liquid disappeared or evaporated first. The alcohol evaporated quickly, leaving the water streak on the lab bench for several minutes. What unique property of water was illustrated by this simple experiment? A) buoyancy B) specific heat C) surface tension D) capillary action
Answer:
B) specific heat
Explanation:
The specific heat of a substance is how much heat per unit mass it need to elevate its temperature by one degree Celsius. Its units are joule per kelvin and kilogram, J/(K kg). In the example given you can observe that water need more heat in order to evaporate compared to the alcohol.
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Answer: Specific Heat
An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms, such as hummingbirds, humans, and whales, have similar skeletal structures. This most directly suggested to biologists that ____________.
a) only the best-adapted organisms can survive
b) advantageous changes can be passed along to offspring
c) most evolution occurs rapidly following a mass extinction
d) dissimilar organisms might have evolved from a distant, common ancestor
e) all of the above
Answer:
Option-D
Explanation:
One of the common belief before the Darwin about the species was that the species can change over time but they do not evolve into another species that is the species do not share the common ancestor.
The collected evidence that the similarity in the skeletal system of the distantly related species like in the humming bird, the whales and the humans suggested that they have evolved from the common ancestor. This observation was the challenge to the pre- Darwinian ideas.
Thus, Option-D is the correct answer.
A client is diagnosed with peripheral arterial disease. A review of the client's chart shows an ankle-brachial index (ABI) on the right of 0.45. This indicates that the right foot has which of the following?
a. No arterial insufficiency
b. Very mild arterial insufficiency
c. Moderate to severe arterial insufficiency
d. Tissue loss to that foot
Answer:
The correct answer is option c.
Explanation:
The ABI or the ankle-brachial index examination refers to a noninvasive and brisk way to determine PAD or peripheral artery disease. The disease takes place when narrowed arteries diminish the flow of blood to the limbs. The condition can result in leg pain at the time of walking and enhances the chances of stroke and heart attack.
On the basis of ABI, one can find that a healthy individual lacking arterial insufficiency exhibits an ABI of about 10. Those with an ABI of 0.95 to 0.5 shows minor to modest arterial insufficiency. The individuals with an ABI of less than 0.50 exhibits ischemic rest pain. Those with the loss of tissue show extreme ischemia and an ABI of 0.25 or less.
Hector and his family came to the United States from Cuba last year. Hector speaks only Spanish and seems unable to learn English despite extended help from an ELL teacher. He is failing all subjects in second grade except for Art and P.E. He was recently evaluated for the possibility of an intellectual disability. The school psychologist administered an intelligence test in Spanish. Scores indicate that Hector has significant cognitive delays. Based on the findings, the IEP team is recommending that Hector receive special education services as a student with an intellectual disability. Did Hector receive a nondiscriminatory evaluation as required by IDEA?
Answer:
Yes he did
Explanation:
Non-discriminatory evaluation: An IDEA precept that allows schools to assess students equally in order to ascertain whether they have a disability, if so, which one and how severe.The assessment has to be conducted in a culturally responsive manner to facilitate fairness.
If the surface barriers of innate immunity, such as the skin or mucous membranes are breached, the second line of defense in innate immunity is (are) the:
Answer:
If the surface barriers of innate immunity, such as the skin or mucous membranes are breached, the second line of defense in innate immunity is (are) the: lymphocytes
Explanation:
The lymphocytes direct and regulate immune responses. Specifically, B lymphocytes produce antibodies to fight against bacteria, viruses and invading toxins. T lymphocytes destroy the body's own cells that have been infected by viruses or that are cancerous.
N 9 Viruses use the host's machinery to make copies of themselves. However, some human viruses require a type of replication that humans do not normally do. For example, humans normally do not have the ability to convert RNA into DNA. How can these types of viruses infect humans, when human cells cannot perform a particular role that the virus requires?
Answer:
This is because the Viron has in its genome a specialized code for synthesising any missed enzyme for replication that is lacking in the host cell.
An example is the replication of the human DNA cells by the Immunodeficiency virus(HIV) . Human cells only have enzymes for copying DNA templates, and lacks the enzyme to convert the HIV RNA genome to human DNA.However these viruses have in its genome; code for synthesising its own RNA polymerase enzymes that copies or transcribed the human DNA to HIV RNA.
This ability of the viral cell to code for the host's enzyme has a therapeutic effect. Drugs can be targeted at the viral polymerase enzymes to reduce the replication and therefore toxicity in the host cells.
Explanation:
_____ includes crude comments or sexual jokes and behaviors that convey hostility toward a particular gender.
Answer:
Gender Harrassment
Explanation:
This could also be called sexism.
In watermelons, bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s). The genes for the two characteristics assort independently. A homozygous plant that has bitter fruit and yellow spots is crossed with a homozygous plant that has sweet fruit and no spots. The F1are intercrossed to produce the F2.
a) What will the phenotypic ratio be in the F2 generation?
b) If an F1 plant is backcrossed with the bitter, yellow spotted parent what phenotypes and proportions are expected in the offspring?
c) If an F1 plant is backcrossed with the sweet, nonspotted parent what phenotypes and proportions are expected in the offspring?
Answer:
A) 9:3:3:1
B) All bitter fruit, yellow spotted offsprings
C) Phenotypes are bitter yellow spotted (4), bitter no spot (4), sweet yellow spot (4), and sweet no spot (4). 1:1:1:1
Explanation:
This is a typical dihybrid cross involving two genes, one coding for fruit taste and the other for spot color. The allele for bitter taste (B) and yellow spot (S) is dominant over the allele for sweet taste (b) and no spot (s) respectively.
Hence, a heterozygous F1 resulting from a cross between an homozygous dominant (bitter fruit, yellow spot) and homozygous recessive (sweet fruit, no spot) will have a BbSs genotype. The heterozygous F1 offsprings are self-crossed and produce gametes BS, Bs, bS, bs. (See punnet square). The F2 offsprings will have the following phenotypes: Bitter fruit, yellow spot (9)
Bitter fruit, no spot (3)
Sweet fruit, yellow spot (3)
Sweet fruit, no spot (1)
Back cross between a F1 offspring (BbSs) and homozygous dominant parent (BBSS) will produce all bitter fruit, yellow spot offsprings (see attached image). BBSS (4), BBSs (4), BbSS (4), and BbSs (4) are the offsprings' genotypes.
For the back cross between a F1 offspring (BbSs) and a homozygous recessive (bbss) parent, the Phenotypes with their proportions are as follows:
Bitter fruit, yellow spot (BbSs, 4)
Bitter fruit, no spot (Bbss, 4)
Sweet fruit, yellow spot (bbSs, 4)
Sweet fruit, no spot (bbss, 4).
The phenotypic ratio in the F2 generation from crossing two heterozygous watermelon plants (BbSs) is 9:3:3:1. A backcross of an F1 plant with a homozygous bitter, yellow spotted parent results in 100% bitter, spotted offspring. A backcross with a homozygous sweet, non-spotted parent yields a 1:1:1:1 ratio of phenotypes.
Explanation:In classic Mendelian genetics, the cross between a homozygous bitter fruit, yellow-spotted watermelon plant (BBSS) and a homozygous sweet fruit, non-spotted watermelon plant (bbss) results in the F1 generation all being heterozygous (BbSs) since bitter fruit (B) is dominant over sweet fruit (b), and yellow spots (S) are dominant over no spots (s).
Phenotypic Ratio in the F2 Generation
The intercrossing of the F1 generation (BbSs) would result in the F2 generation having a phenotypic ratio of 9:3:3:1. This is because each characteristic (bitter vs sweet and spotted vs non-spotted) is inherited independently, resulting in four possible phenotype combinations: bitter with spots, bitter without spots, sweet with spots, and sweet without spots.
Backcross with Bitter, Yellow Spotted Parent
If an F1 plant (BbSs) is backcrossed with the bitter, yellow spotted parent (BBSS), the expected phenotypes and proportions in the offspring would be all bitter with spots (100% B-S-), due to the dominance of the bitter and spotted traits.
Backcross with Sweet, Nonspotted Parent
Similarly, if an F1 plant (BbSs) is backcrossed with the sweet, non-spotted parent (bbss), the resulting phenotypes and proportions expected in the offspring would be a 1:1:1:1 ratio. This results from the combination of the F1 heterozygous traits with the recessive sweet, non-spotted parent's traits.
A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species, each of which eats only a certain type of food. None of the species can fly and their balancing organs (halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap.If the malesʹ halteres have species-specific size, shape, color, and use in courtship displays, and if the speciesʹ ranges overlap, then the speciation events may have been driven, at least in part, by which of the following?
A) autopolyploidy
B) allopolyploidy
C) species selection
D) sexual selection
E) habitat differentiation
Answer:
The correct answer is option D) "sexual selection".
Explanation:
Sexual selection is a type of natural selection at which species of one sex chose their biological mates based on specific traits that represent an advantageous trait for the species. In this case, if the males halteres are used in courtship displays and the females select them in base of its size, shape and color, the speciation events may have been driven, at least in part, by sexual selection.
The correct answer is sexual selection.
Which of the following correctly describes polyphyletic groups?
organisms that share all of the same traits
organisms that share a common trait, inherited from a common ancestor
organisms that share a common ancestor, but leave out some of the descendants
organisms that happen to share a common trait, even though they evolved
Answer:organisms that happen to share a common trait, even though they evolved
Explanation: polyphyletic groups have similar characteristics but
that have been grouped together
They do not share an immediate common ancestor.
Polyphyletic group is characterized by organisms that happen to share a common trait.
Polyphyletic groups are groups of organisms that include species with similar characteristics that have evolved from more than one ancestor. These characteristics may appear to be similar due to convergent evolution rather than deriving from a common ancestor.