Answer:
Principles of Geology
Explanation:
J. Henslow gifted Darwin the first volume of Principles of Geology, written by Charles Lyell. The book explains about the old age of the earth. Accordingly, the slow rate of several geological processes suggests that the earth is very old.
Darwin read the book as the ship was crossing the Atlantic and learned about geological processes occurring over the millions of years. For example, he learned that the earth's surface was not formed by some catastrophic event.
In his book, Lyell explained the slow and gradual geological processes like erosion gave rise to the vast landscapes present on the earth's surface.
Darwin compared the time taken by geological processes to form the earth's surface and reasoned if these millions of years were enough to support the evolution of species.
Give three adaptive advantages of fungi involving spores and their production.
Answer:
Spores are made by the millions, so some of them are likely to land in a good place to grow. Spores are lightweight and can drift around on the slightest air currents, so spores are spread far and wide. Spores have hard outer coverings to protect them until they begin to grow.
Explanation:
Appendix works in __________
a. neutralize pepsine
b. store calcium
c. contributes in immunity
d. detoxify poison
Answer:
c. contributes in immunity
Explanation:
The mass of the lymphatic tissues that lack any capsule is known as lymphatic nodules. The lymphatic nodules are scattered in mucous membranes that line the various tracts.
The appendix has an aggregation of lymphatic nodules. The lymphatic nodules of the appendix contain immune cells to protect against diseases or infection. It prevents any possible entry of pathogen and subsequent infection through digestive system.
Gymnosperms and angiosperms have the following in common except
a.seeds c.ovaries.
b.pollen d.ovules.
Answer: c.ovaries.
Explanation:
Gymnosperms and angiosperms are plants with seeds, where the great advantage present in both groups is the presence of pollen grain (which is the male gametophyte), which eliminates the need for water during reproduction.
In gymnosperms, the gametophyte grows in structures called strobiles or cones. The male gametophyte is released in the wind and, with lucky, landing in a female strobile and germinates. The female gametophyte develops within the strobile leaf, waiting for the pollen grain.
On the other hand, the most evolutionarily successful is the angiosperm group, the plants with flower and fruit. Flowers were decisive in animal pollination. The flower contains the eggs and can be grouped in inflorescences or solitary. The flowers have structures to attract pollinators, such as beautiful colored petals.
Gymnosperms and angiosperms both produce seeds and pollen, but only angiosperms have ovaries. Both have ovules that develop into seeds after fertilization.
Explanation:Gymnosperms and angiosperms are both seed-producing plants but they differ in a few ways. Both produce seeds and pollen, which makes options a and b common traits. However, the main difference comes in when we look at options c and d. Ovaries are present in angiosperms but not in gymnosperms. These are important in the formation of fruit after pollination. On the other hand, both gymnosperms and angiosperms have ovules which develop into seeds after fertilization. Hence, the correct answer for this question is c. ovaries.
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Normally, wild violets have yellow petals with dark brown markings end erect stems. Imagine you discover e plant with white petals, no markings, and prostrate stems. What experiment could you perform to determine whether the non-wild- type phenotypes are due to several different mutant genes or to the pleiotropic effects of alleles at e single locus? Explain how your experiment would settle the question.
Answer:
It is fascinating to observe two distinct characters presented by the same plant. The inheritance of this plant can be determined easily by crossing the pure violets exhibiting yellow petals with dark brown marking and erect stems with violets exhibiting no markings, white petals, and prostate stems.
The F1 progeny will originate as a hybrid of the two characters. These F1 plants will then be crossed between themselves and the F2 progeny would be clearly evaluated. If the F2 plants come in the phenotypic ratio of 3: 1, then it would indicate the pleiotropic effect of the alleles found in a single locus. If any other combinations arise post crossing, it would indicate that the non-wild type phenotype is because of many distinct mutant genes.
Darwin's study of feeding patterns in Galapagos finches was one of the cornerstones of our understanding of adaptation and evolution. The results of that study don't apply just to finches however, but to birds of all shapes and sizes. Why is beak morphology so important to birds?
a. different species of birds can divide ecological spaces between them my matching the morphology to the food source.
b. most birds are strict herbivores so they can each feed on different types of plants depending on food availability.
c. the beak of most birds is integral to interspecies communication and differentiation
d. much like hindlimb morphology, beaks vary to allow different locomotory lifestyles
e. all of the above are correct
Answer:
a. different species of birds can divide ecological spaces between them my matching the morphology to the food source.
Explanation:
Beak morphology allows the birds to select the suitable food type. The various species of Galapagos finches differ from each other in beak shape and size irrespective of their origin from common seed-eating stock.
The modification of beak shape and size into several directions allowed the finches to occupy the available empty ecological niches with respect to food types.
Diversification also reduced the competition between them and allowed the finches to colonize various ecological niches in accordance with their respective beak morphology.
In June 2003, the FDA approved the FluMist vaccine for influenza, which is administered by squirting tiny amounts of vaccine into each nostril. This would be a(n) __________ vaccine.
a. inactivated vaccine
b. attenuated vaccine
c. recombinant vaccine
d. acellular vaccine
Answer:
The correct option is: b. attenuated vaccine
Explanation:
FluMist is the trade name of the live attenuated influenza vaccine, manufactured by MedImmune. This vaccine is used for the prevention of influenza, also called flu.
It is an attenuated vaccine which is given in the form of nasal spray.
An attenuated vaccine alters the pathogen by reducing its virulence and makes it harmless.
A human pancreatic cell obtains O2 and necessary molecules such as glucose, as amino acids, and Cholesterol from its environment, and it releases CO2 as a waste product. In response to hormonal signals, the cell secretes digestive enzymes. It also regulates its ion concentrations by exchange with its environment. Based on what you have just learned about the structure and function of cellular membranes, write a short essay (100–150 words) that describes how such a cell accomplishes these interactions with its environment.
Answer:
Cellular membranes or plasma membranes has many functions. Some of these include regulation of cellular transport, and responding to cellular signals or hormones.
Cellular TransportThe plasma membrane is made up of the phospholipid bilayer with embedded transmembrane proteins. This makes the cell membrane semi-permeable. Movements of substances depend on the composition of the molecules e.g. glucose and amino acids, as needed by the pancreatic cells. These are larger and uncharged molecules and can't pass freely through the membrane so they utilize the transmembrane proteins via attaching to carrier proteins. This is called passive transport. On the other hand, in active transport, ATP is used to transfer molecules, like Hydrogen, from a low to high electrochemical gradient.
Other kinds of cellular transport are:
Osmosis and diffusionEndocytosisExocytosisCellular SignallingThe cell membrane is able to signal other neighboring cells by utilizing complex proteins. These proteins may take form as receptors or markers.
Membrane ReceptorsThey act as receivers of extracellular signals and spark intracellular processes. These receive signals from hormones, growth factors, etc.
Membrane MarkersThese allow the cells to identify each other and respond if this cell is needs further development as in organ development, or a foreign body to the system.
ALL of the following are functions of the liver, EXCEPT:
a. Storage of bile
b. Carbohydrate metabolism
c. Detoxification of the blood
d. Protein and lipid metabolism
e. production of bile and phagocytosis
Answer:
The correct answer is option A. storage of bile.
Explanation:
The liver is the organ that is present on the right side of the abdomen and is almost the size of a football. Liver provides a different role in the body but major function of the liver is to detoxification of blood coming from the digestive tract. It produces different proteins and helpful in metabolizing all three major macromolecules that are protein, carbohydrate, and fat. The liver also produces the bile that is helpful in digestion.
Bile that produces and moves from the liver through bile ducts and stored in the gall bladder concentrated and secreted during or after food intake to assist the digestion process.
Thus, the correct answer is option A. storage of bile.
The liver does not store bile; instead, bile is stored in the gallbladder. The liver's functions include carbohydrate metabolism, detoxification of the blood, protein and lipid metabolism, and production of bile. Hence the correct answer is option A- Storage of bile.
Explanation:The liver has a wide array of functions, but storage of bile is not one of them. Instead, the liver's roles include carbohydrate metabolism, detoxification of the blood, protein and lipid metabolism, and the production of bile which is involved in the emulsification and digestion of fats. The bile produced by the liver is stored in the gallbladder, not the liver itself. Therefore, the correct answer to the question 'ALL of the following are functions of the liver, EXCEPT:' is option a. Storage of bile.
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Given that the function of egg yolk is to nourish and support the developing chick, explain why egg yolks are so high in fat, protein, and cholesterol.
Answer:
viviparous animals like birds have a disadvantage compare to viviparous animals like mammals (humans) because the mammal embryo will have a steady supply of nutrients throughout its development through the umbilical cord. The egg needs to have all the necessary nutrients to shape the organism.
The egg yolk along with the egg white supply the "raw materials" necessary for the embryo development.
Protein is used to make structural component like muscles and bones also enzymes are a type of protein.
Fats and cholesterol provide energy. Cell membranes are phospholipid bi-layers. Lipids are fats hence the need for them. Some hormones also contain protein and lipids.
Egg yolks are high in fat, protein, and cholesterol because they provide the necessary calories, building blocks, and hormonal precursors needed for the development of the chick. Unlike mammals, birds and reptiles rely on yolk rather than parental support for embryonic development, requiring a high concentration of nutrients in the yolk. Albumen also plays a supportive role but is not the primary nourishment source.
Explanation:The function of egg yolk is to nourish and support the developing chick, and this is why egg yolks are high in fat, protein, and cholesterol. The high fat content is crucial as it provides the necessary calories for growth, functioning similarly to how shortening improves the tenderness of a baked cake. Proteins are essential for the construction of new tissues and serve as the building blocks of the developmental processes for the chick. The presence of cholesterol, despite being a concern for some due to its association with heart disease in humans, is essential for the production of hormones and the development of cell membranes.
Mammalian embryos develop inside the mother and receive their nutrients through the placenta, which is why mammalian eggs are low in yolk. In contrast, bird and reptile embryos develop outside the mother's body and rely on a larger yolk supply for sustenance during their growth, thus requiring a higher concentration of yolk.
The albumen, or egg white, serves additional roles such as providing water and protein to the embryo and protecting the egg through its ability to congeal at certain temperatures. Yet, it is the yolk that serves as the primary resource for the nourishment of the growing embryo, with the high nutrient content being essential for the development of the chick until it hatches.
For fertilization to occur in humans, only one sperm is needed to weaken the barrier that surrounds the egg.
a. True
b. False
Answer:
False
Explanation:
Approximately 200 out of 200 million sperms ejaculated during intercourse reach the general vicinity of the egg. They sperms must undergo capacitation during which dilute inhibitory factors fluids of the female reproductive tract weaken the membrane of the sperm head so that head of the sperm can be broken easily when it came in contact with the egg.
The first sperm to reach an egg isn’t the one to fertilize it because the egg is surrounded by a gelatinous membrane called the zona pellucida. Outside this layer, a layer of small granulosa cells also present.
Therefore, it requires numerous sperm to clear a path through these barriers before one of them can penetrate the egg and fertilize it.
The final enzymatic breakdown in the digestive processes of most proteins and carbohydrates are accomplished by:
a. enzymes secreted in the stomach and pancreas
b. enzymes secreted in the pancreas
c. enzymes secreted in the brushborder
d. enzymes secreted in the mouth and small intestine
e. enzymes secreted in the pancreas and large intestine
Answer:
b. enzymes secreted in the pancreas
Explanation:
The pancreas is a gland which is situated in the abdomen. It functions as endocrine as well as an exocrine gland.
The endocrine part of the pancreas is the islets of Langerhans which secretes hormones insulin and glucagon directly into the bloodstream.
It releases pancreatic juice that contains digestive enzymes into the duodenum of the small intestine.
The final digestion of carbohydrates, protein and fats occur in the duodenum with the pancreatic enzymes.
The enzymes include:
Protein digesting enzymes trypsin and chymotrypsin. They break down protein into dipeptides and amino acids. Pancreatic amylase which digests starches into sugar. Lipase in association with bile breaks down fats into fatty acids and cholesterol.The final enzymatic breakdown in the digestive processes of most proteins and carbohydrates are accomplished by: c. enzymes secreted in the brushborder.
What is an enzyme?An enzyme can be defined as a biological catalyst that typically speeds up (accelerates) the rate of a chemical reaction such as the break down of food by the digestive system, especially by lowering the activation energy of its chemical reactants.
Basically, the enzymes secreted in the brushborder are mainly responsible for the final enzymatic breakdown in the digestive processes of most proteins and carbohydrates.
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Parts of some plants and animals grow according to the Fibonacci sequence of numbers developed by an Italian mathematician in which each number is the sum of the previous two numbers. The shell of the chambered nautilus the seeds in a sunflower and pineapples all exhibit a structure called the ""Fibonacci spiral""
Answer:
C Patterns
Explanation:
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The shell of the chambered nautilus the seeds in a sunflower and pineapples all exhibit a structure called the "Fibonacci spiral". This phenomenon represents the pattern phenomena by cross-cutting.
What is the Fibonacci spiral?A series of numbers in which every number is the sum of the two its previous numbers Fibonacci spiral. It starts at 0 and 1, the sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, and goes on forever. Xn+2= Xn+1 + Xn is the mathematical equation that is used to describe or represent the Fibonacci sequence.
Several people have claimed that there are many special properties of this numerical sequence. They say that it is “nature’s secret code” for the construction of perfect structures. Some examples given are the Great Pyramid at Giza and the iconic shape of the seashell that is used as the cover of most mathematical textbooks. But most of these assumptions are incorrect.
Therefore, this is a pattern phenomenon represented by cross-cutting.
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Most amino acids are coded for by a set of similar codons (see Figure 17.6). Propose at least one
evolutionary explanation to account for this pattern
The pattern of multiple codons encoding single amino acids could be an evolutionary protection mechanism against harmful mutations, providing a level of robustness and adaptability to organisms.
Explanation:Most amino acids are indeed coded for by a set of similar codons. This redundancy in the genetic code, often referred to as degeneracy, can be explained from an evolutionary perspective. One possible explanation for this pattern could be that it provides a level of protection against harmful mutations. If a mutation occurs at the third position of a codon, it's often less likely to result in an amino acid change, which might provide an advantageous buffer against potentially harmful mutations. These synonymous mutations, or silent mutations, won't fundamentally change the resulting protein. Such a system would have been favored by natural selection, providing a level of robustness and adaptability to living organisms.
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The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
a.a body cavity. c.mesoderm
b.a complete digestive tract d.true tissues.
Answer:
The correct answer is option D. True tissues.
Explanation:
The cell that made sponge does not form the tissue however sponge have cells that play important role and specific for specific function but does not have true tissues.
In other animal phyla cells form tissue or organ or organ systems and called as true tissues.
Thus, the correct answer is option D. True tissues.
It is mainly based on the true tissues.
Sponges are the multicelled organism of the phylum Porifera. The body of the sponges has various channels and pores, that allows water circulation.
What is a sponge made up of?Sponges are multicellular organism that consists of pores and channels in their body for water circulation and lacks specific tissues. They have cells assigned with specific roles and functions but lack true tissues unlike animals of the other phyla.
The animals of the various phylum are classified based on the body cavity, tissues, symmetry, fate of the blastopore.
Therefore, option d. is correct.
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Within six months of effectively using methicillin to treat S. aureus infections in a community, all new S. aureus infections were caused by MRSA. How can this best be explained?
a. A patient must have become infected with MRSA from another community.
b. In response to the drug, S. aureus began making drug-resistant versions of the protein targeted by the drug.
c. Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.
d. S. aureus evolved to resist vaccines.
Answer:
B
Explanation:
The rate of mutations on the S. Aureus population increased when exposed to antibiotics over time. This gave rise to a few mutants of the bacteria that could survive the methicillin antibiotic. This is because the mutation altered a protein target of methicilin (beta-lactam binding proteins) on which the antibiotic acted upon. These populations increased as the others were eliminated by the antibiotic – the way natural selection works. Over time, these mutations were transferred to other populations of bacteria by these MRSA through ‘sexual’ horizontal gene transfer, causing whole bacteria populations to be resistant against methicilin.
List three dangerous recreational drugs and explain what they do to the nervous system.
Answer:
Three dangerous recreational drugs: crack cocaine, heroin, methamphetamines
Explanation:
Recreational drugs are the psychotropic drugs that induce an intoxicating effect. The three types of recreational drugs are depressants, stimulants, and hallucinogens.
The drugs affect the nervous system and induce hallucinations, euphoria, enhanced alertness and locomotion, low blood pressure, anesthesia, analgesia and memory impairment.
Some of the dangerous recreational drugs are crack cocaine, heroin, methamphetamines and alcohol.
All of the following are directly associated with photosystem I except
A) harvesting of light energy by chlorophyll.
B) receiving electrons from plastocyanin.
C) P700
D) photolysis
E) passing electrons to ferredoxin.
Answer:
The correct answer is D) photolysis
Explanation:
Photolysis is a process in which light energy is used by photosystem II to split water which generates oxygen, H⁺ions end electrons. oxygen is released in the atmosphere and inhaled by animals and electrons are used to generate energy.
The electron released by the splitting of water is transferred to the first electron acceptor called pheophytin. This electron is passed through a series of complex and produce energy in the form of ATP and NADPH.
The process of photolysis does not occur in photosystem I because lysis of water takes place and electron is passed from photosystem II to photosystem I.
Photolysis is not directly associated with Photosystem I. Instead, it's a process that occurs in Photosystem II, where water molecules are broken down into oxygen, protons, and electrons.
Explanation:The correct answer is D) photolysis. Photosystem I is a protein complex involved in the light-dependent reactions of photosynthesis. Its primary functions include harvesting light energy by chlorophyll (option A), receiving electrons from plastocyanin (option B), possessing a reaction center known as P700 (option C), and passing electrons to ferredoxin (option E).
In contrast, photolysis - the breaking down of molecules using light - is not directly associated with Photosystem I, but instead with Photosystem II, where water molecules are broken down into oxygen, protons, and electrons.
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Are disaccharide polymers?
Answer:
Yes they are polymers of monosaccharides.
Explanation:
Disaccharides are polymers of monosaccharides, which are simple sugar molecules such as glucose. Monosaccharides, monomers, are linked by glycosidic bonds to make disaccharides.
Example; the linkage of glucose and fructose to make sucrose.
List two ways that the Light Dependent reactions are similar to the production of ATP in the Mitochondria.
Answer:
The process of ATP synthesis in both chloroplast and mitochondria is similar:
1. Generation of electrochemical gradient across the membrane: The movement of electrons generates a difference in the concentration of protons across the membrane in both organelle. Due to this, an electrochemical gradient is established.
2. Movement of protons or hydrogen ions through ATP synthase: The generation of electrochemical gradient leads to the movement of options across the membrane through embedded ATP synthase enzyme.
Thus, ATP production in both the organelles is similar.
Why does NADH and FADH2 donate their H+ to the electron transport chain readily?
a. Because they have a high affinity for the H+
b. Because they have a low affinity for the H+
c. Because the H+ add stability to their structures
d. All of the above
Answer:
b. Because they have a low affinity for the H+
Explanation:
All electrons that enter the transport chain come from NADH and FADH2 molecules that are produced in earlier phases of cellular respiration: glycolysis, pyruvate oxidation and the citric acid cycle.
NADH is very good at donating electrons in redox reactions (that is, its electrons are at a high energy level), so you can transfer your electrons directly to complex I and transform it back into NAD +. The movement of electrons through complex I in a series of redox reactions releases energy, which the complex uses to pump protons from the matrix into the intermembrane space.
FADH2 is not as good for donating electrons as NADH (that is, its electrons are at a lower energy level), so it cannot transfer its electrons to complex I. Instead, it introduces electrons to the transport chain through complex II, which does not pump protons through the membrane.
The strategy of vaccination to fight diseases uses what type of immunity?
A. Non-specific immunity
B. Cell-mediated immunity
C. Natural immunity
D. Specific immunity
E. Passive immunity
Answer: Passive immunity
Explanation:
The strategy of vaccination was a type of passive immunity. Passive immunity can be introduced artificially when antibodies are given as a medication to the non immune individual.
This is done in case of vaccination, attenuated form of bacteria is injected or orally given to the individual to evoke immune response when the body is exposed to the same bacteria again.
The attenuated form of bacteria evoke the immune system to produce memory cells which will kill the bacteria when it is encountered for the second time.
Within a cell, the amount of protein made using a given mRNA molecule depends partly on
a. the degree of DNA methylation.
b. the rate at which the mRNA is degraded.
c. the number of introns present in the mRNA.
d. the types of ribosomes present in the cytoplasm.
Answer:
b. the rate at which the mRNA is degraded.
Explanation:
DNA is transcribed into mRNA which then joins ribosomes present in the cytoplasm to serve as a template for protein synthesis. Regulation of gene expression occurs at several levels.
One such regulatory mechanism is the stability of mRNA and the rate of its degradation which in turn affects the availability of template for the process of protein synthesis and thereby keeps a check on the total amount of protein being formed in a cell.
For example, a very short life span of bacterial mRNA (few minutes) allows them to regulate the pattern of protein synthesis quickly in response to the changes in surroundings.
The amount of protein synthesized from an mRNA molecule is influenced by the rate of mRNA degradation, which affects its stability and the duration of its presence in the cytoplasm for translation.
b is correct
Explanation:The amount of protein made using a given mRNA molecule within a cell depends on several factors, one of which is the rate at which the mRNA is degraded. mRNA carries the genetic message from the DNA during the process known as transcription, and it dictates the synthesis of proteins through translation in conjunction with ribosomes and other cellular machinery.
The mRNA is short-lived, and its stability in the cytoplasm is crucial as it influences the amount of time available for translation. A longer mRNA lifespan allows for more protein production. Thus, the correct answer to the student's question is option b. the rate at which the mRNA is degraded.
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Is there any reason that mitosis could not occur in a cell whose genome is haploid?
Answer:
No, there's no reason at all. mitosis can occur in any type of cell. The fundamental purpose of mitosis is to create identical cells. So, depending on the organism like plants or protist mitosis could even be involved in the production of gametes. In animals mitosis is a cell division that is mostly used for growth or tissue repair.
The two primary functions of the ears are balance and hearing.
a. True
b. False
Answer: True
Explanation:
The ear is a organ found in the body of mammals and other animals that helps in hearing.
The ear consists of outer part and inner part. The outer part of the ear converges the sound waves and the transfers to the ear canal.
The sound is then amplified inside the ear and we hear sound. There is a fluid which is found inside the inner ear contains a fluid that helps in balancing of the body.
What is the digestive system?
a. the body's blood-transporting system
b. the body's system for gas exhange
c. the body's food-processing system
d. the body's system of nerves
Answer:
The body's food-processing system.
Explanation:
Digestion may be defined as the process of break down of large food particle into the small food particle that can be easily absorbed in the body. The digestive system includes the gastrointestinal tract and the digestive organs.
Digestive system is mainly involved in the processing of food. Carbohydrates are broken down into simple sugars, proteins into amino acids, lipids into simple fats and nucleic acids into nucleoside.
Thus, the correct answer is option (c).
Answer:
c; the body's food-processing system
Explanation:
The digestive system is the group of organs that break down food in order to absorb its nutrients. The nutrients in food are used by the body as fuel to keep all the body systems working.
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Bacterial cells usually have cell walls, as do animal cells.
a. True
b. False
Answer:
False.
Explanation:
Bacteria are the prokaryotic organism that lacks the well developed nucleus and the membrane bound cell organelle. The animal cells are the eukaryotic organisms.
Bacteria cells have cell walls that are made of the peptidoglycan layer. The cell wall of bacteria are important as it protect themselves from the extreme environment. The animal cells do not contain cell wall and they have plasma membrane only in their structure.
Thus, the correct answer is option (b).
Sketch the oxygen binding curves for myoglobin and haemoglobin and describe what each curve means in terms of the functions of each of these proteins.
Answer:
The oxygen dissociation curve for hemoglobin is sigmoidal where as for myoglobin it is hyperbolic.
Explanation:
Oxygen dissociation curve: A graphical representation of relationship between partial pressure of O2 and percentage saturation of hemoglobin with oxygen is known as O2-dissociation curve. It is sigmoidal or S- shaped curve. The amount of O2 that can bind with Hb is determined by partial pressure of oxygen. The percentage of Hb that is bound with O2 is called percentage saturation of Hb.
In human adults, at pO2 of 25 mm of Hg the hemoglobin is 50% saturated with oxygen. This partial pressure is called P-50.
Hemoglobin shows S shaped curve due to cooperative binding of oxygen that is binding of first oxygen increases the ability of second oxygen binding and so on. One Hb can carry 4 oxygen molecules.
In case of myglobin, it has more affinity for oxygen but it has only one Fe+2 group, there is no cooperative binding. The curve obtained will be hyperbolic than being sigmoid.
Please find the attached image which shows both the curves. (Image reference: Evolution of Myoglobin and Hemoglobin ; Author and Curator: Larry H. Bernstein, MD, FCAP )
Since myoglobin has more affinity for oxygen its P-50 value is less, that is at low partial pressure of oxygen myoglobin gets 50% saturated. But the P-50 value for hemoglobin is high which means comparatively more partial pressure of O2 is needed for hemoglobin to be 50% saturated.
Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in
(A) G1.
(B) G2.
(C) prophase.
(D) metaphase.
In the cell cycle, G1 is the phase when the cell has the least amount of DNA. This DNA is duplicated during S phase, meaning the cell has twice as much DNA in the G2 phase. So, if Cell A has half as much DNA as cells B, C, and D, then Cell A is likely in the G1 phase.
Explanation:In the cell cycle, the amount of DNA a cell has can help determine which phase it is in. The cell cycle consists of interphase (G1, S, and G2 phases), and the mitotic phase (including prophase, metaphase, anaphase, and telophase). During the G1 phase of the cell cycle, a cell has the least amount of DNA because it hasn't duplicated its DNA yet. DNA replication occurs during the S phase, so by the G2 phase, the cell has twice as much DNA as it did in G1. Thus, if Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue, Cell A is most likely in the G1 phase.
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Cell A is most likely in the G1 phase of the cell cycle, a stage prior to DNA synthesis, as it has half the amount of DNA than cells B, C, and D, which presumably already completed the S phase (DNA replication).
Explanation:Cell A is most likely in the G1 phase of the cell cycle. The G1 phase is a period in the cell cycle during interphase, before DNA synthesis (S phase). In G1 phase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. At this stage, it has half as much DNA as it will have after it completes the S phase. Therefore, cells B, C, and D, each having twice as much DNA, are probably in the G2 phase, metaphase, or any phase after DNA replication (S phase) happened, during which the amount of DNA in the cell has already been doubled.
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Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?
a. Proto-oncogenes first arose from viral infections.
b. Proto-oncogenes are mutant versions of normal genes.
c. Proto-oncogenes are genetic "junk."
d. Proto-oncogenes normally help regulate cell division.
Answer:
The correct answer is D.
Explanation:
Proto-oncogenes code for proteins that usually help to regulate cell growth and differentiation.
If they acquire a mutation, they become oncogenes and therefore can induce cancer.
Additionally, if they increase the amount of certain proteins concentration or acquire chromosomal translocations they can also become oncogenes.
Psychological and physiological dependence on a drug is called tolerance.
a. True
b. False
Answer:
False.
Explanation:
Tolerance is when, after being exposed to a certain drug for a long period of time, the body can no longer respond to the same dose that used to trigger a biological response, so the dose has to be increased.