Answer:
a. Water
Explanation:
An arrangement of chlorophyll and other pigments in the chloroplast is known as photosystems. In the photosynthetic eukaryotes, there are two photosystems, Photosystem II and Photosystem I. Photosystem I uses chlorophyll a, with reaction centre as P700. Photosystem II uses chlorophyll a with reaction centre P680.
During light reaction or photochemical reaction of photosynthesis, the light energy causes the removal of an electron from chlorophyll a reaction centre of Photosystem II P680. After losing an electron the P680 is deficient of an electron. P680 takes an electron from photolysis of a water molecule into eletron, H⁺ ions and O⁻² ions.
Breathing is more difficult in higher altitudes because the
a. air weighs less
b. partial pressure of atmospheric oxygen is lower
c. partial pressure of atmospheric carbon dioxide is higher
d. partial pressure of atmospheric nitrogen is lower
e. partial pressure of atmospheric oxygen is higher
Answer:
Option (b).
Explanation:
Breathing may be defined as the inhalation of oxygen and exhalation of carbon dioxide. The breathing depends on the various internal and external factors.
The partial pressure of oxygen is directly proportional to the breathing and the inhalation of oxygen in the body. The altitude contains lower atmospheric pressure and the partial pressure o the oxygen decreases at high altitude. The decrease in the partial pressure of the oxygen reduces the affinity of oxygen with hemoglobin and thus an individual feels difficulty in breathing.
Thus, the correct answer is option (b).
A pea plant heterozygous for plant height, pod shape, and flower color was selfed. The progeny consisted of 272 tall, inflated pods, purple flowers; 92 tall, inflated, white flowers; 88 tall, flat pods, purple; 93 dwarf, inflated, purple; 35 tall, flat, white; 31 dwarf, inflated, white; 29 dwarf, flat, purple; 11 dwarf, flat, white. Which alleles are dominant in this cross?
Answer:
Tall , Inflated and Purple are dominant
Explanation:
The given phenotypical count is as follows -
Tall, inflated pods, purple flowers- [tex]272[/tex]
Tall, inflated, white flowers - [tex]92[/tex]
Tall, flat pods, purple - [tex]88[/tex]
Dwarf, inflated, purple- [tex]93[/tex]
Tall, flat, white - [tex]35[/tex]
Dwarf, inflated, white- [tex]31[/tex]
Dwarf, flat, purple- [tex]29[/tex]
Dwarf, flat, white- [tex]11[/tex]
Total number of species
[tex]272+92+88+93+35+31+29+11\\= 651[/tex]
Let Trepresents tall allele and t represent dwarf allele , P represents allele for purple flower and p represents allele for white flower , I represents alleles for inflated flower and i represents allele for
Phenotypical ratio
Tall, inflated pods, purple flowers- TTIIPP
Tall, inflated, white flowers - TTIIpp
Tall, flat pods, purple - TTiiPP
Dwarf, inflated, purple- ttIIPP
Tall, flat, white - TTiipp
Dwarf, inflated, white- ttIIpp
Dwarf, flat, purple- ttiiPP
Dwarf, flat, white- ttiipp
Hence, Tall , Inflated and Purple are dominant allele
The dominant alleles in this cross are tall, inflated, and purple.
Explanation:In this cross, the dominant alleles can be determined by analyzing the traits that appear in the offspring. By looking at the progeny, we can see that tall plants, inflated pods, and purple flowers are the most common traits. Therefore, the dominant alleles for plant height, pod shape, and flower color are tall, inflated, and purple respectively.
Enzymes are important in cell's chemical reaction. Describe what a enzyme's role in chemical reactions is and explain what an enzyme does. The following key words may help you structure your response: active site, enzyme-substrate complex, and activation energy. Please try to use...
Answer:
Enzymes are proteins that allow certain chemical reactions to take place much quicker than the reactions would occur on their own.
Explanation:
Enzymes function as catalysts, which means that they speed up the rate at which metabolic processes and reactions occur in living organisms.
Answer:
Enzymes are proteins that catalyze chemical reactions that occur in living things. They accelerate the speed of reactions, which contributes to metabolism. Without enzymes, many reactions would be extremely slow.
Explanation:
Each enzyme is specific to a type of reaction. That is, they only act on a given compound and always perform the same type of reaction. The compound on which the enzyme acts is generally referred to as substrate. The great enzyme-substrate specificity is related to the three-dimensional form of both.
The enzyme binds to a substrate molecule in a specific region called a binding site. For this, both the enzyme and the substrate undergo conformation change for the socket.
They fit perfectly like keys in locks. We call this behavior the Key-Lock Theory.
While many non-avian dinosaurs achieved gigantic sizes, the Sauropods were the true giants of the Mesozoic. in fact, the largest terrestrial vertebrates to ever live are members of this clade. However, it is not easy to estimate how large an animal was from just a fossil skeleton. Which of these is a method by which dinosaur body size is estimated?
a. Paleontologists measure the length of the legs from the hip to the foot and using a 2/3's power relationship convert that to a mass
b. Paleontologists use Archimedes principle and dunk the entire skeleton of a Sauropod into a pool of water and measure the water displacement
c. Paleontologists make scaie models with estimates of muscle mass, density and skin morphology and then estimate the volume of the model and scale it up
d. a and b
e. a and c
Answer:
The correct answer is option d. "a and b".
Explanation:
Plenty of methods had been developed to estimate the body size of dinosaurs such as the gigantic Sauropods. One of the first estimations that paleontologists used was the Archimedes principle, consisting in dunking the entire skeleton of a Sauropod into a pool of water and measure the water displacement or more precisely small dinosaur models. However this method requires the preservation of almost the entire skeleton. A more used and useful method is to measure the length of the legs from the hip to the foot and using a 2/3's power relationship convert that to a mass. This method is more used since it only requires a couple of leg bones, which are often well preserved.
The closest relatives of fungi are thought to be the
a.animals c.mosses
b.vascular plants d.slime molds
The closest relatives of fungi are thought to be the ANIMALS (Option A).
In recent years, it has been estimated that ancestral fungi split from animals approximately 1.540 billion years ago.
Moreover, ancestral plants split from animals approximately 1.550 billion years ago.
In consequence, it has been proposed that fungi are more closely related to animals than to plants (i.e., fungi and animals share a more recent common ancestor with each other than with plants).
In conclusion, the closest relatives of fungi are thought to be the ANIMALS (Option A).
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Fungi are most closely related to animals based on recent DNA evidence. They share a common ancestor, causing them to have several similarities such as their mode of nutrition and cell structure.
Explanation:The closest relatives of fungi are believed to be the animals. This is based on recent DNA evidence which suggests that fungi and animals share a common ancestor and thus, are more closely related to each other than they are to plants or other organisms. Essentially, Fungi and animals fall under the same supergroup, known as Opisthokonta. Fungi and animals have several similarities including their mode of nutrition and the structure of their cells.
While fungi were often categorized as plants in the past, they share more similar characteristics with animals, such as the storage of carbohydrates as glycogen (like in animals) instead of starch (like in plants). Therefore, choice a. animals would be the most accurate answer.
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The plasma half-life of a hormone is inversely related to its metabolic clearance rate (MCR).
a. True
b. False
Answer:
True
Explanation:
The plasma half-life of a hormone is inversely related to its metabolic clearance rate (MCR) is true Statement.
Half life of a hormones is the life after which a hormone looses its half of pharmacological and physiological life whereas metabolic clearance rate is the volume of biological units cleared completely of drug metabolites as measured in unit time.
The people who "discovered" the structure of the DNA molecule are:
a. Lewis &Clark
b. Schleiden & Schwann
c. Henderson & Hasselbeck
d. Watson & Crick
Answer:
Watson & Crick
Explanation:
DNA is present as the genetic material of all the living organism. The DNA contains of the nitrogenous bases, pentose sugar and the phosphate group.
The X ray structure of the DNA was given by Franklin. The structure of the DNA molecule and its properties was fully explained by the Watson and crick. They explains the polarity, base pairing and the arrangement of the DNA structure.
Thus, the correct answer is option (d).
James Watson and Francis Crick discovered the structure of the DNA molecule in 1953. They proposed the double helix model of DNA, which has proven to be crucial in the field of genetic engineering. The correct answer to the student's question is 'd. Watson & Crick'.
Explanation:The DNA molecule was discovered byJames Watson and Francis Crick.
In 1953, they proposed the double helix model of DNA. Their discovery was extremely important because it showed how genetic information is passed from one generation to another. This laid the groundwork for a whole new area of scientific research known as genetic engineering.
The answer to the question is: d. Watson & Crick.
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What does cell specialization in multicellular organisms aloows cells to do?
Answer:
Explanation:
Cell specialization is also called cell differentiation. Through this process, specialized cells form from the unspecialized cells. Then many cells are formed and determined to form specialized functions.
The stem cells are the unspecialized cells which form a different kind of specialized cells.
The muscle cells, nerve cells, sperm cells, red blood cells are specialized cells perform different specialized functions. All these cells arise from stem cells. The nerve cells receive impulse, muscle cells can contract, etc.
There are certain inductive signaling genes that send the signal to the differentiated cells. These signaling molecules are called ligands. These ligands move to another cell to produce specialized cells. In other words, there are some transcription factors and genes responsible for such cell differentiation and the formation of specialized cells.
Another example is zygote, which is an unspecialized cell. This is also a totipotent cell that has the potentiality to reproduce different cells.
What is a Barr body, and where is it found in a cell? b) Define the Lyon hypothesis.
Answer:
Barr body may be defined as the one of the inactive X chromsome of the human female. The human female consists of XX chromosome whereas XY in male. To compensate the extra X chromosome in female one of the X chromosome become inactive and known as barr body. The barr body is found in the somatic cells.
Lyon hypothesis:
Lyon hypothesis states that dosage compensation occur in human females by the random inactivation of one of the X chromosome. The inactivated X chromosome is named as barr body. The lyon hypothesis was given by Mary Lyon.
Most cells cannot harness heat to perform work because
a. heat does not involve a transfer of energy.
b. cells do not have much thermal energy; they are relatively cool.
c. temperature is usually uniform throughout a cell.
d. heat can never be used to do work.
Answer:
Temperature is usually uniform throughout a cell (Ans. C)
Explanation:
Heat or thermal energy is a kinetic energy. That is connected with the random movements present in the atoms. Temperature is usually uniform throughout the cell so the most cell can not harness heat to perform work.
Heat is a type of energy which is transfer from one body to another body due to the temperature difference.
It can only perform work if it is transferred from one source which is warmer to a body which is cooler. The temperature in living organisms is usually kept very constant due to the process of homeostasis.
Most cells cannot harness heat to do work because temperatures within the cell are typically uniform, so there's no heat gradient for work to be conducted. Heat tends to be lost instead.
Explanation:Most cells are not able to harness heat to perform work because heat energy is often dissipated as waste during biochemical reactions. The correct option is c. The temperature is usually uniform throughout a cell. This means that there isn't a high temperature gradient in the cell, which would be needed in order for heat to be used for work. For heat to be harnessed and used for work, there must be a temperature difference because work is done when heat flows from a hotter area to a cooler one. Without a temperature gradient, heat energy cannot be used to perform work within a cell and is instead lost to the surrounding environment.
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Approximately 16% of this alien genome is comprised of nucleotides containing C, and 22% is comprised of nucleotides containing Y. Given this information, calculate the percentage of the alien genome that is comprised of nucleotides containing G, T, A, and X. (a) _____% of the alien genome is comprised of G. (b) _____% of the alien genome is comprised of T. (c) _____% of the alien genome is comprised of A. (d) _____% of the alien genome is comprised of X.
Answer:
(a) 16 % of the alien genome is comprised of G.
(b) 17% of the alien genome is comprised of T.
(c) 17% of the alien genome is comprised of A.
(d) 22 % of the alien genome is comprised of X.
Explanation:
Assuming the alien follows Chargaff's rules which states that DNA from any cell of any organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases.
So if:
16% contains C ; 16 % pairs with G = 32% C-G pairing.
22% contains Y ; 22 % pairs with X = 44% X-Y pairing.
44% G-C + 32% X-Y = 76%
100%-76% = 34% the remaining should be split between T and A which is 17% each one.
Using Chargaff's Rule, 16% of the alien genome is comprised of G, and 22% is comprised of T. Percentages for A and X cannot be determined without additional information.
Explanation:Given that 16% of the alien genome is comprised of nucleotides containing C, and 22% is comprised of nucleotides containing Y, we can calculate the percentages of the remaining nucleotides by applying Chargaff's Rule, which states that DNA is a double helix that is held together by base pairs: A pairs with T, and G pairs with C. This means that the percentage of nucleotides containing G will be equal to that of C, and T will complement Y assuming that Y pairs with T in this alien genome, as A pairs with T in Earth organisms.
(a) Since 16% of the alien genome is comprised of C, then 16% of the alien genome is also comprised of G, as G pairs with C.
(b) If 22% is comprised of Y, and assuming Y pairs with T, then 22% of the alien genome is comprised of T.
(c) To find the percentage of A, we would need additional information since the question doesn't provide a direct pairing percentage. Given no other information, the percentage of A remains undetermined in this hypothetical situation.
(d) Without additional information about what X pairs with, we cannot accurately determine the percentage of X in the alien genome. If X pairs with an unknown or non-standard base or does not directly pair with one of the given nucleotides, we would not be able to apply Chargaff's Rule.
Mumps virus is a member of ____________ family and _____________ genera.
Answer:
Family: Paramyxoviridae
Genus: Rubulavirus
Explanation:
Mumps virus is a member of family Paramyxoviridae, subfamily Paramyxovirinae, and the genus Rubulavirus.
The family Paramyxoviridae includes single-stranded RNA viruses with helical symmetry of capsid. These are enveloped viruses and mostly affect the animals as their host.
The Rubulavirus uses the gastrointestinal tract to enter the host and has an incubation period of 2-3 weeks. These viruses are characterized by the formation of large multinucleated cells called syncytium during infection.
What term is used to describe the relationship of the DNA strands to each other?
a. parallel
b. antiparallel
c. congruent
d. non-congruent
e. recumbent
Answer:
The correct answer will be option-B.
Explanation:
Deoxyribose nucleic acid or DNA is the genetic material of the organism which is made up of nucleotide monomer. The structure of DNA is made up of two strands of nucleotides coiled in a helical structure thus providing a double-helical shape to the structure.
Each nucleotide of a strand is composed of a five-carbon sugar, phosphate group and nitrogenous bases. These molecules are arranged in anti-parallel fashion in DNA which provides the polarity to the DNA strand. One strand is read from the 5' to 3' direction whereas another form 3'to 5' direction.
Thus, Option-B is the correct answer.
Which of the following observations helped Darwin shape his concept of descent with modification?
a. Species diversity declines farther from the equator.
b. Fewer species live on islands than on the nearest continents.
c. Birds live on islands located farther from the mainland than the birds’ maximum nonstop flight distance.
d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.
Answer:
The correct answer will be option-D.
Explanation:
Darwin is best known for his theory of evolution which he proposes after collecting the specimens of plants and animals on his voyage.
He observed the similarity and differences of the morphological pattern as well as the species present in the area. On the basis of his conclusions, he suggested that organism get traits from their parents and species to change over time also called descent with modification.
One of the evidence that supported his concept is that he observed plant species in South America and found that these species closely resembled the species of the tropical regions of South America rather than species of the temperate region of Europe as the habitat was same.
Thus, option-D is the correct answer.
Option D- South American temperate plants being more similar to tropical plants in South America than to temperate plants of Europe- helped shape Darwin's concept of Descent with Modification. This observation suggested organisms from a common geographical location were likely descendants of a common ancestor, supporting biography and the theory of evolution.
Explanation:The observations that helped Charles Darwin shape his concept of Descent with modification, primarily pertain to the geographical distribution of species, also known as biogeography. Several of the options you provided contain elements of this concept. However, the option which most explicitly illustrates this is:
d. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.
This observation supported Darwin's argument that geographic proximity is a better predictor of relationships between species than similarity in environment. This suggests that these species likely originated from a common ancestor and then evolved differently due to different environmental pressures - a phenomenon central to the concept of Descent with modification.
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DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that
a. humans and chimpanzees share a relatively recent common ancestor.
b. humans evolved from chimpanzees.
c. chimpanzees evolved from humans.
d. convergent evolution led to the DNA similarities.
Answer:a. humans and chimpanzees share a relatively recent common ancestor.
Explanation:
Humans and chimpanzees are not evolved from one another, but both have a common ancestors. Humans share a common ape ancestor with chimpanzees who is expected to live 6-8 million years ago. The humans and chimpanzees have been evolved differently from this ancestor.
The most likely explanation for this result is that humans and chimpanzees share a relatively recent common ancestor.
What is the common ancestor of humans?Scientists tend to believe that our common ancestor with the chimpanzee lived between 9 and 7 million years ago. Sahelantropus tchadensis is the closest hominin to this date that we know of.
With this information, we can conclude that the most likely explanation for this result is that humans and chimpanzees share a relatively recent common ancestor.
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Know the difference between lipid soluble and water soluble hormones and how they elicit their effects on target cells.
Answer:
Water soluble hormone binds to the membrane bound receptors whereas lipid soluble hormones bind to the internal/intracellular receptors.
Explanation:
Hormones are called regulators because they can either stimulate or inhibit the target cell's activity.
They perform their action by binding to specific protein on target tissue called hormone receptors. Each receptor is specific for a particular hormone. The hormone-receptor complex bring about the biochemical changes in the target cell.
Hydrophillic or water soluble hormones interact with the membrane bound receptors. They result in the generation of secondary messengers such as cyclic AMP. Secondary messengers bring about the cascading action amplifying the final effect. That is why even a very small quantity of hormone is sufficient for a powerful cascading effect.
Lipid soluble hormones can diffuse through the plasma membrane and thus they bind to the intracellular receptors. The hormone-internal receptor complex enters the mucleus and regulates gene expression. Example: steroid hormones and thyroid hormones.
Lipid-soluble hormones can cross the cell membrane and directly influence gene expression, while water-soluble hormones bind to receptors on the cell membrane and trigger intracellular signaling pathways.
Explanation:Lipid-soluble hormones, such as steroid hormones, can pass through the cell membrane and bind to receptors in the cytoplasm or nucleus of target cells. Once inside the cell, they directly influence gene expression and protein synthesis, leading to changes in cell function.
Water-soluble hormones, such as peptide hormones, cannot pass through the cell membrane. Instead, they bind to receptors on the cell membrane surface and trigger intracellular signaling pathways, which ultimately result in the desired cellular response.
Overall, the main difference between lipid-soluble and water-soluble hormones is their ability to cross the cell membrane and where their receptors are located.
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The system of slavery began to replace indentured servitude because
Africans began to arrive in the colonies.
indentured servants began demanding higher “freedom dues.”
the need for a steady supply of low-cost labor increased.
Answer:
the need for a steady supply of low-cost labor increased
Explanation:
In the beginning (18th century) before slavery, indentured servitude was a way for poor Euopeans to pay their way for the costly voyage across the Atlantic to the New Colonies. Their contract terms were fixed in which they worked for their landowners or shippers until their debt was paid. As more and more of these indentured servitude served their contracts and became free, they also increased the demand for labor as they became landowners. The need for labor increased and the cost of indentured servants also increased.
White landowners, especially in early Virginia, turned to Africa for servitude. With time, using race to undermine Africans, greed for profits by landowners resulted in slavery and enactment of Slave Law in 1641.
Slavery began to replace indentured servitude due to the need for a consistent, cheap labor force in the American colonies. The arrival of Africans and the demands for freedom dues by indentured servants added challenges, leading to colonists to shift towards slavery.
Explanation:The system of slavery began to replace indentured servitude primarily due to socioeconomic reasons during the colonial period. Indentured servitude often led to social mobility and advancement once a servant's contract had ended, which created an inconsistent labor source for colonists. Colonists required a consistent, cheap workforce to cultivate profitable cash crops such as tobacco and cotton.
The arrival of Africans provided a new source of cheap labor. By classifying these individuals as property, colonists created an unchanging workforce. In addition to this, the demand for “freedom dues” from former indentured servants was hard to maintain. Furthermore, the economic need for a steady supply of low-cost labor due to the expanding plantation economy was a driving factor.
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Recognize progeny ratios that imply the existence of recessive lethal alleles.
Answer:
Explanation:
From Mendel’s Law of Segregation we can expect, as a result of a monohybrid cross, a phenotypic ratio of 3:1 in the offspring.
If you get a different ratio such as 2:1, and notice that a particular genotype does not appear in the offspring, you can suspect that genotype is lethal.
Mendel’s Law of Independent Assortment on the other hand says that the offspring resulting from a dihybrid cross will have a phenotypic ratio of 9:3:3:1.
If you get numbers that don't match the expected ratios, and are smaller numbers like 4:2:2:1, and notice that a particular combination of alleles does not appear, you can suspect that allele is recessive and lethal in an homozygous individual.
If the pinsulin receptor, a, example of an integral membrane protein, is cotranslationally inserted into the ER membrane with the N-terminus on the cytosolic side of the membrane and the C-terminus in the lumen of the ER, which side of the protein would you expect to bind to the ligand, pinsulin, when the protein is found on the cell surface?
(A) N-terminal end of the protein will bind pinsulin
(B) Neither will bind to a ligand because both ends of the protein will be extracellular and will compete with each other
(C) C-terminal end of the protein will bind pinsulin
(D) Neither will bind to a ligand because both ends of the protein will be cytoplasmic
Answer:
The correct answer is option C.
Explanation:
As the proteins are produced in the endoplasmic reticulum membrane, they amalgamate with the vesicles and then they are conducted towards the membrane's cell surface where they act as an integral membrane protein.
The outer end will bind with the ligand and the other one will get attached towards the cytoplasm. Thus, the pinsulin in the given case will combine with the C terminus of the protein.
Which of the following serves as reservoir hosts for all three of the pathogens that cause salmonellosis, influenza, and toxoplasmosis?
a. cats
b. reptiles
c. birds
d. mice
e. cattle
Answer: Birds option c is correct.
Explanation: Birds represents an example of natural reservoir host for the three zoonotic pathogens. For example poultry for salmonellosis and influenza from which house cats, humans and birds of prey can be infected. In the case of Toxoplasma gondii pigeons represent a better example of reservoir host.
Natural selection changes allele frequencies because some ______ survive and reproduce better than others.
a. alleles
b. loci
c. species
d. individuals
Answer:
The correct answer is option D. Individuals.
Explanation:
Natural selection is the process in which some individuals adapt traits or trends according to the environment changes in order to service and reproduce more. These trends are pass from one generation to another generation.
Natural selection is the first time described by Charles darwin.
Thus, the correct answer is option-
d. individuals
Some individuals survive and can reproduce better compared to others.
Natural selection is a method of selection of the organisms that have adapted to the change in their environment and can survive and reproduce in the variation.
What survives and adapts to natural selection?Individuals having better traits and attribute over others can survive and even can continue the generation of the species as they have adapted to the frequency change of the allele.
The alleles are the alternative gene form for a particular trait and characteristic and are located on the chromosome of the organism as they get passed from generation over generation.
Loci or the locus is a specific point where the allele for a specific trait lies on the chromosome. Species is the classification level of the taxonomy and includes organisms having major similar traits.
Therefore, option d is correct.
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Simply, transcription is a copy of __________
a. proteins from mRNA
b. mRNA from DNA
c. proteins from DNA
d. mRNA from proteins
Answer:
b. mRNA from DNA
Explanation:
Transcription is the process of synthesis of RNA using a DNA template strand. The process of transcription occurs inside the nucleus in eukaryotes as their DNA is present in the nucleus.
The process includes unwinding of DNA double helix to expose the DNA template strand. The enzyme RNA polymerase binds to the specific start sites on the DNA template strand and starts making its RNA copy.
The newly formed RNA undergoes modification in eukaryotes before serving as a template for protein synthesis. However, in prokaryotes, the process of transcription and translation can occur simultaneously.
A functional group on an amino acid that is polar and can become negatively charged: ___________
Answer:
Carboxylic acid.
Explanation:
Amino acids are made up of the amine group, carboxyl group, hydrogen and R hydrophobic chain. Amino acids are the monomers of the protein and they are coded by the particular codons.
Amino acids contains both the amino group and the carboxyl group. The carboxylic group is a polar group and becomes negative charged when the pH of the solution is greater than the pKa value of the amino acids.
Thus, the answer is carboxylic acid.
Glycolyis occurs ________________
a. photosynthesis
b. aerobic respiration only
c. both aerobic and anaerobic respiration
d. anaerobic respiration only
Answer:
Both aerobic and anaerobic respiration.
Explanation:
Glycolysis may be defined as the process of break down of glucose molecules for the formation pf ATP with the help of enzymes and chemical factors. Glycolysis occurs in the cytosol of the organism.
Glycolysis may occur in the presence of organism known as aerobic respiration. The glycolysis can occur in the absence of oxygen as well known as anaerobic respiration. The steps involved up to the formation of pyruvate molecule from the glucose is same in case of aerobic and anaerobic respiration.
Thus, the correct answer is option (c).
No two people are genetically identical, except for identical twins. The main source of genetic variation among humans is
a. new mutations that occurred in the preceding generation.
b. genetic drift.
c. the reshuffling of alleles in sexual reproduction.
d. environmental effects.
Answer:
c. the reshuffling of alleles in sexual reproduction.
Explanation:
During gametogenesis, meiosis occurs in reproductive cells. As a result, haploid gametes are produced. During meiosis, a process called ‘crossing over’ occurs in the pachytene stage of prophase I of meiosis. During crossing the chromosome segments are exchanged between non-sister chromatids of homologous chromosomes. Exchange of chromosome segment creates a new combination of genes or genetic recombination and produces hybrids. Thus, genetic variation occurs in all sexually reproducing organisms due to crossing over.
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to
a. disruption of mitotic spindle formation.
b. suppression of cyclin production.
c. myosin denaturation and inhibition of cleavage furrow formation.
d. inhibition of DNA synthesis
Answer:
a. disruption of mitotic spindle formation.
Explanation:
Vinblastine is a chemotherapeutic drug which is used to restrict cancer cell proliferation. During metaphase, it binds to microtubular proteins which play a very important role in mitotic spindle formation. If spindles will not form then during anaphase, the sister chromatids will not separate and mitosis will not take place. This is how hyper-proliferative cancerous cells are controlled from dividing and cancer is treated using this drug.
Which of the following is a scientific statement?
A. A shark can jump as high as a low flying helicopter as shown in pictures on the internet.
B. Dinosaurs were killed off by a great flood as described in the Bible.
C. Unicorns used to exist because there are paintings of them from years ago.
D. According to DNA comparisons, humans share a common ancestor with chimpanzees.
E. Dogs are smarter than cats because it's easier to train them.
The correct answer is D. According to DNA comparisons, humans share a common ancestor with chimpanzees.
Explanation
A scientific statement is a statement made based on scientific evidence, that is, a scientific statement is the result of several tests focused on testing a hypothesis or proposal. These scientific statements can be developed in different areas of knowledge such as science, biology, physics, mathematics, geometry, among others. they are also predominant in the exact sciences because in the human sciences it is complicated to establish scientific statements because human behavior does not obey exact laws. According to this definition, option D. is the correct answer because it refers to DNA tests between humans and chimpanzees and therefore this is based on scientific evidence and tests.
Describe the key features of the Watson-Crick model for DNA structure.
Answer:
Watson and Crick proposed the double helical model of DNA.
Explanation:
- This model says that DNA exist as double helix. It has two polynucelotide strands running in opposite direction i.e the strands are anti-parallel.
- Each polynucleotide strand is made up of several nucleotide liknked together by phophodiester bonds.
- The two strands are not coiled upon each other but the double strand is coiled upon itself around a common axis like the spiral stair case. Here base pairs forms the stairs and backbone of two strands form railing. Back bone contains sugar and phosphate.
- The base pairing is specific, adenine always pairs with thymine and guanine always pairs with cytosine. Thus if we see any base pair, it consists of one purine and one pyrimidine.
- The two strands of DNA thus show complementary base pairing.
- The strands are held together because of hydrogen bonding between the bases in opposite strand.
- One full helical turn involves ten base pairs and the base pairs are stacked 3.4 A apart.
- This form is called as B-form of DNA.
Describe the key chromosome behaviors during meiosis that lead to haploid gametes.
Meiosis is a process of cell division through which four haploi cells are produced from a diploid cell. Haploid cells are those that contain a single set of chromosomes. Gametes or sex cells are haploid cells. Thus, the goal of meiosis is to generate sex cells. For this reason, when a sperm and an egg join in fertilization, their two sets of chromosome haploids come together to form a new complete diploid set, that is, a completely new DNA or genome.
Meiosis is a complex process that involves two distinct phases: meiosis 1 and meiosis 2. Each of them is composed of several stages: prophase, metaphase, anaphase and telophase.
Meiosis1: First cell division of the diploid, known as reductive, as it results in cells with half the genetic load.
Prophese1: The first step consists in preparing the DNA to become two different sets, so that the genetic material intersects and a sort of dividing line emerges in the cell.
Metaphase1: The chromosomes are located in the center of the cell and begin to separate. Random genetic distribution has already been carried out.
Anaphase1: Each string of DNA tends to a cell pole, forming two haploid poles.
Telophase1: The plasma membrane separated and gives rise to two haploid cells.
Meiosis2: Known as a duplicate phase, it resembles mitosis: two whole individuals are formed by duplicating the DNA.
Prophase2: Haploid cells created in meiosis1 condense their chromosomes and break the nuclear envelope.
Metaphase2: As before, chromosomes tend toward the middle of the cell, preparing for a new division.
Anaphase2: The genetic material tends to separate and migrate to the poles of the cell, enlisting the new process of cell division.
Telophase2: The cell membranes separate again and result in four haploid cells, each with a different distribution from the complete genetic code of the individual.
During meiosis, homologous chromosomes undergo pairing, random alignment, crossover for genetic variation, and segregation, followed by the separation of sister chromatids resulting in four unique haploid gametes.
Explanation:Key Behaviors of Chromosomes During Meiosis
Meiosis is crucial for the production of haploid gametes, which are essential for sexual reproduction. In meiosis I, homologous chromosomes pair up during prophase I and subsequently align randomly during metaphase I. This results in the separation of homologous chromosomes during anaphase I. Genetic variation is introduced as these chromosomes can exchange genetic material through a process called crossover. Meiosis II resembles mitosis, where sister chromatids separate during anaphase II. This process reduces the chromosome number by half and ensures that each gamete contains a unique set of genetic information.
In summary, the behaviors of chromosomes during meiosis involve the pairing and segregation of homologous chromosomes, crossover for genetic variation, and the separation of sister chromatids, all leading to the production of four genetically distinct haploid cells.
Protozoans are the only organisms that can convert nitrogen from the air into chemical compounds that plants can use.
a. True
b. False
Answer: False
Explanation:
Protozoans are not the organism that fix nitrogen for the plants. The organism that fix nitrogen to convert it into a form which can be used by plants are known as diazotrophs.
These are bacteria and archae that fix nitrogen gas found in the atmosphere into more usable form such as ammonia.
These organism can grow without any external source of fixed nitrogen. Example: Rhizobia and azospirillium.