cAMP activates cAMP-dependent protein kinase by




bindingregulatory subunits and inducing their release from the
catalyticsubunits.




stimulating itsphosphorylation.




stimulating thedimerization of kinase subunits.




stimulating therelease of a translational inhibitory protein
bound to itsmRNA.

Answer:

I would suggest this as the best reason behind the detection of the harmful enantiomer in the body after the prescription of the beneficial one is that the human liver contains an enzyme that can convert the "good" R-enantiomer into the "bad" S-enantiomer.

Explanation:

Thalidomide (C13H10N2O4) is one of the most controversial drugs that exist nowadays due to the unfortunate error of prescribing this drug to pregnant women because its harmful effects were unknown at that time.

This drug possesses two enantiomers (optical isomers with mirror-image structures). Thalomide has a racemic mixture of both enantiomers, that is, an equal ratio of both 1:1. The R-enantiomer is a highly effective sedative with sleeping effects; whereas the S-enantiomer is teratogenic, i.e. it causes birth deffects by inhibiting the growth of new blood vessels.

After this disaster, researchers decided to prescribe this drug to patients with leprosy, cancer, and other diseases but, of course, not to pregnant women because as it turns out, the "good" enantiomer is also a great drug to treat them.

While they suggested the best way to prevent the presence of the "bad" enantiomer was to separate them into different drugs, they discovered that the human liver contains an enzyme that can convert the "good" R-enantiomer into the "bad" S-enantiomer.

Although there are still many research studies done because its mechanism is still not understood completely, I would suggest this as the best reason behind the detection of the harmful enantiomer in the body after the prescription of the beneficial one.

Thalidomide, with two enantiomeric forms, has both beneficial and harmful effects. Over time, even if only the beneficial enantiomer is given, both enantiomers will be present in the body due to 'racemization'. This is where the body's environment can convert some of the useful enantiomer into the harmful one.

Thalidomide, a drug containing two enantiomeric forms, has both beneficial and harmful effects. This is a characteristic seen in many drugs, where one isomer can have the desired pharmacological effect, and the other isomer can cause detrimental side effects. In the specific case of thalidomide, one enantiomer helps reduce morning sickness, while the other is a teratogen, capable of causing birth defects.

Over time, even if only the beneficial enantiomer is synthesized and administered to patients, both the harmful and beneficial enantiomers can be found in the body. This could be due to 'racemization' - a process where one enantiomer changes into the other. Studies have shown that in the body's environment, under physiological conditions, thalidomide can undergo racemization.

Racemization can be thought of as an equilibrium where, over time and under specific conditions, both enantiomer forms can be present. Essentially, the body's environment can convert some of the beneficial enantiomer into the harmful one, causing the secondary adverse effects. Despite only the beneficial form being given, the body's natural biochemistry facilitates the presence of both.

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Answer:

Transcription, mRNA (processing, transport, localization and stability), translation.

Explanation:

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Answer:

Blood contains both solid an liquid components in it. On centrifugation blood shows- 45% solid portion called formed elements and 55% liquid components called blood plasma.

Blood plasma is programmed to carry the nutrients and other important particles to organs whereas cellular components play roles in carrying oxygen and providing immunity.

The major components of blood plasma shows:

1. water: 90%

2. proteins-albumin, globulin and fibrin-7-8%  

3. salts: 1%

The composition of the formed elements shows:

1. Erythrocyte (RBC)

2. Leukocyte (WBC)

3. Thrombocytes (platelets)

Answer: a. True

Explanation: These postulates were formulated by Robert Koch as a result of his experiments with healthy and infected mice. The postulates are often used to determine if a phatogen causes a disease. These are:

Answer: B. Poorly adapted individuals never produce offspring

Explanation:

Natural selection is a theory that states organisms adapts to its environment due to differences in their phenotypes. So, individuals with favorable traits are more likely to survive and reproduce. It is a key mechanism of evolution, which is the change in traits of a population over generations.

Populations respond to natural selection if they contain heritable variation among them, wich means that individuals differ in the traits they transmit to their offspring.

Because of the environmental selection pressures, individuals produce more offspring than their environment can support. The pressure determines which individuals will survive and reproduce, while others will die because of predation or diseases. So, natural selection is based on the observations of adapted individuals.

Answer:

i think it is b but i ill let you know since im taking the test rn

Explanation:

k i took the test and re edited this it is b poorly adapted one so yeah have a great day

Answer:

a. mental deterioration, memory loss, and personality changes

Explanation:

This disease is common in the elderly, and is a common form of dementia. It affects the parts of the brain that control thinking, memory and language. People may have difficulty remembering things that happened recently.

People may not recognize their family members. They may have difficulty speaking, reading or writing.

Answer:

False

Explanation:

The organisms in Domains Bacteria and Archaea are able to thrive in every possible environment present on the earth. They are found in oceans, air, fresh water, soil, inside the body of living beings, hot water springs and even in hydrothermal vents.

Some of these organisms can thrive in the absence of oxygen as they perform anaerobic metabolism. For example, the enteric bacteria are anaerobic as oxygen is not available to them.

The evolution of unique ability to withstand the extremes of the conditions allows the archaeans to thrive under extreme climatic conditions. It includes halophiles, thermophiles, etc.

Answer:

C) carbon dioxide is incorporated into PGA.

Explanation:

Light reactions of photosynthesis include splitting of the water molecule in presence of sunlight and release of electrons and oxygen gas, generation of electrochemical gradient during electron transfer from PSII to NADP+ via PSI and synthesis of ATP and NADPH.

The ATP and NADPH are used in the light-independent phase of photosynthesis which includes the Calvin cycle.

The first stage of the Calvin cycle is carbon fixation during which carbon dioxide is fixed into 3-PGA (3-phosphoglyceraldehyde). Carbon fixation is followed by reduction and regeneration of RuBP.

Answer:

The correct option is 'a': All the answers are correct.

Explanation:

Since plant's are abundant and can manufacture their own food hence they serve as the beginning of all the food chains hence option 'b' is correct.

In the process of photosynthesis the plants make use of carbon dioxide, sunlight , water, in presence of a pigment called chlorophyll present in plant cells in organelles called as plastids to yield glucose which is a carbohydrate or simplest sugar and release oxygen into the atmosphere. Hence options 'c' and 'd' are also correct.

Final answer:

The synthesis of vitamin D is reduced by sunscreen, not enhanced. Vitamin D is critical for calcium absorption and bone health, and it is activated by the liver and kidneys.

Explanation:

The characteristic of vitamin D that is not accurate is that its synthesis is enhanced by the use of sunscreen. In fact, the synthesis of vitamin D is reduced with the use of sunscreen because it blocks ultraviolet (UV) radiation from the sun, which is necessary for the skin to produce vitamin D3, or cholecalciferol. The liver and kidneys then activate the vitamin by converting cholecalciferol to its active form, calcitriol. This activation process facilitates calcium absorption from the small intestine, promotes calcium reabsorption in the kidneys, and assists in bone tissue rebuilding. Therefore, the correct answers from the given options would be it is activated by the liver and kidney (a), it causes the kidney to excrete less calcium in the urine (b), and it facilitates calcium absorption from the small intestine (d).

Final answer:

Two normally pigmented parents with an albino child each carry one dominant allele for pigmentation and one recessive allele for albinism, giving them the heterozygous genotype Aa.

Explanation:

When two normally pigmented parents have an albino child, the genetic inheritance involved follows a recessive pattern. Albinism is a condition characterized by a lack of pigment in the skin, hair, and eyes and is caused by a recessive allele. If a child expresses this recessive trait, it means that both parents must have provided a copy of this recessive allele for albinism. Thus, the genotypes of each parent must be heterozygous, meaning they each carry one dominant allele for normal pigmentation and one recessive allele for albinism. This can be represented as Aa, where 'A' is the dominant allele for normal pigmentation, and 'a' is the recessive allele for albinism.

In the context of Mendelian genetics and monohybrid crosses, such as the cross that would involve the two heterozygous parents, a Punnett square predicts that there is a 3:1 phenotypic ratio in the second filial (F2) generation. However, in the first generation (F1), all offspring would display the dominant phenotype. In cases like the one presented, albinism reveals the underlying genotype of the parents due to its recessive nature. The appearance of the recessive phenotype in their offspring unequivocally indicates that both parents were carriers of the albinism trait.

Genotype determination from offspring phenotypes can similarly be applied to other recessively inherited disorders, like alkaptonuria mentioned in Figure 12.6, or examples of epistasis in mice coat color inheritance. Understanding parental genotypes using offspring phenotypes is a foundational concept in genetics and illustrates the predictive power of monohybrid crosses.

Answer:B. It would not develop male genitals

Explanation:

Testosterone is the male sex hormone. It is an anabolic steroid. It is responsible for the development and maturation of internal genitalia in males. Internal genetalia includes the testes and prostate gland development which aids in production of sperms and seminal fluid.

Thus in the abscenece of testosterone the gonads will not develop internal genitals.

Answer:

True

Explanation:

Formation of endospore (sporulation) occurs in some organisms such as bacteria.  Sporulation occurs during unfavourable environmental conditions. Sporulation is a process to preserve genetic material during unfavourable environmental conditions. The vegetative cell forms a thick-coated, dormant and resistant spore called endospore.

Endospore was discovered by John Tyndall. It is a resting spore and helps bacteria to overcome the unfavourable environmental conditions.

On the return of favourable environmental conditions, the endospore germinates to form new bacteria cell. Since this process does not involve meiosis, the new bacterial cell is genetically identical to the original vegetative cell.

Answer: Seral stage

Explanation:

The seral community commonly known as sere. It is an intermediate stage which is found during the ecological succession in an ecosystem.

This is an intermediate stage that comes before every stage of ecological succession advancing towards its climax community.

It starts with the pioneer species and keeps on evolving until climax community is attained.

Hence, the correct answer is option C

The correct answer is A. Breast

Explanation:

BRCA-1 that stands for Breast Cancer Type 1 Susceptibility Protein is a tumor suppressor gene and protein related to breast cancer. This means, BRCA-1 can stop cells from developing into cancer, although the function of this gene can change and even be suppressed and thus, cancer might develop due to this. BRCA-1 is located in chromosome 17 in humans and act in cells by repairing DNA or in some cases destroying it, which stop possible mutation that can lead to cancer. Due to this, it is believed by studying BRCA-1 and the correct function of it or possible mutation it might be possible to know the risk for breast cancer in individual as well as detecting first stages of Breast Cancer. Thus, BRCA-1 is mainly related to Breast Cancer.

The correct answer is D. They have two successive sets of teeth including milk teeth and permanent adult teeth

Explanation:

In biology, a diphyodont is an animal that has two different sets of teeth, this often means the animal has a set of baby teeth that are later replaced by permanent teeth, this occurs in most mammals including humans. Additionally, diphyodont differ from other types of animals that have either only one set of teeth (monophyodonts), for example, toothed whales or change their teeth permanently (polyphyodont), for example, crocodiles. Thus, mammals are diphyodont because "they have two successive sets of teeth including milk teeth and permanent adult teeth".

Answer:

Explanation:

The genetic information present in all cells can be  compared to a book of blueprints prepared for the construction  of a large, multipurpose building.

-At different times, all of the  blueprints will be needed, but only a small subset is consulted  during the work on a particular floor or room.

-Similarly in the case of cells all the necessary genetic information is present but but only a subset of genes is  expressed in any particular cell.

Regulation of gene expression alters the gene function in many ways.

For example in prokaryotes-

The lac operon is an  inducible operon, in which the presence of a key metabolic  substance which is lactose in this case, initiates  transcription of the  operon, allowing synthesis of the proteins encoded by the  structural genes.

In case of repressor operon: Transcription of the structural genes is controlled by a repressor  protein that is synthesized by a regulatory gene, which is also part of  the operon. It binds to the operon and blocks the movement of Rna polymerase.

Answer:

Biologists describe the structure of protein at four levels: Primary, secondary, tertiary and quaternary.

Explanation:

1. Primary structure: It is the sequence of amino acids in the polypeptide chain. It only gives us the positional information of amino acids within a protein like which one is first, which one is second and so on. We can see only peptide bonds in primary structure.

Also the first amino acid is known as N-terminal and the last as C-terminal.

2. Secondary structure: The protein thread folds either in the form of helix or beta pleated sheet to form the secondary structure.

In alpha helix, there is hydrogen bonding between every fourth amino acid. Example keratin protein of hair.

In beta pleated sheets, two or more polypeptide strands are held together by intermolecular hydrogen bonding.

3. Tertiary structure: The long polypeptide chain usually folds upon itself like a hollow wollen ball. This is termed as tertiary structure. Involves several linkages like hydrogen bond, hydrophobic bond, ionic bond, covalent bond, van der walls forces. Active sites are formed and protein gains functionality. Example: myoglobin

4. Quaternary structure: Quaternary structure is formed when there are more than one polypeptide chains. For example: hemoglobin has four helical polypeptide chains.

Proteins have four levels of structure essential to function: primary (amino acid sequence), secondary (local folding into α-helices or β-pleated sheets), tertiary (three-dimensional folding of the entire peptide chain), and quaternary (arrangement of multiple subunits).

The structure of protein is essential for its function and is organized into four distinct levels: primary, secondary, tertiary, and quaternary. The primary structure of a protein consists of its unique sequence of amino acids. As for the secondary structure, it is characterized by local folding into patterns such as α-helices and β-pleated sheets. The tertiary structure represents the further three-dimensional folding of the entire peptide chain, resulting in a complex globular shape. When a protein consists of more than one polypeptide chain, they associate to form the quaternary structure, which is the arrangement of these multiple subunits.

Each level of protein structure is critical to the protein's ultimate function. Disruption of these structures, such as through denaturation, can result in loss of function. The structure is maintained by various interactions including hydrogen bonding, ionic bonds, disulfide linkages, and dispersion forces.

Answer:

Mendel is known as the father of genetics. He explained the law of segregation by the monohybrid cross. The monohybrid cross involves the cross of a single trait at a time.

Law of segregation explains that at the time of formation of gametes, the allele pairs get separated from the pairs of trait. The concept of dominance was also explained. The traits that express itself even in the heterozygous condition is known as dominant trait (T). The trait that can not express itself is known as recessive trait (t).

For example:

Parents TT        ×       tt.   (Laws of segregation)

Gamete   T                  t

F1 generation  Tt.

Selfing of F1 generation

Tt       ×        Tt

Offspring :   TT (tall) , Tt (tall) , Tt (tall) , tt (dwarf).

The phenotypic ratio is tall : dwarf (3 : 1)

Final answer:

Mendel's law of segregation states that alleles for each gene segregate during the production of gametes, resulting in a 3:1 phenotypic ratio for dominant to recessive traits in a monohybrid cross of the F2 generation. This separation is due to the process of meiosis, where homologous chromosomes segregate into daughter cells.

Explanation:

Mendel's Law of Segregation

Gregor Mendel's law of segregation is a fundamental principle of genetics that explains how alleles (the different versions of a gene) are separated into individual gametes (the reproductive cells) during the process of meiosis. According to this law, an individual with two alleles for each trait (one from each parent) will separate these alleles so that each gamete receives only one allele. This segregation results in the equal likelihood of offspring inheriting either allele from the parents.

Monohybrid Cross and the Predicted 3:1 Ratio

When conducting a monohybrid cross, which is a genetic cross involving a single trait with two alleles, three potential genotypes could result in the F2 generation: homozygous dominant, heterozygous, and homozygous recessive. The presence of dominant alleles results in the dominance of a specific trait, and because homozygous dominant and heterozygous genotypes express the dominant phenotype, this leads to a phenotypic ratio of 3:1 for dominant to recessive traits in the F2 generation. This phenotypic ratio is supported by the Punnett square, a predictive tool used to determine the genotypes and phenotypes of offspring.

The physical basis of this law lies in the first division of meiosis, where homologous chromosomes and their gene alleles are separated into two daughter nuclei. This fundamental genetic mechanism was not understood during Mendel's time but is now considered the cornerstone of how traits are inherited.

PCR involves the repeated cycling through denaturation, annealing, and extension stages at varying temperatures, which doubles the quantity of DNA molecules each time. The process can amplify a target DNA sequence dramatically after multiple rounds.

The Polymerase Chain Reaction (PCR) includes three main cycles that result in repetitively doubling the number of DNA molecules. Each cycle consists of three steps: denaturation, annealing, and DNA synthesis that occur at different temperatures. The first step, denaturation, occurs at high temperatures, approximately 95 °C, where the double-stranded DNA template is separated. The next step, annealing, happens at a lower temperature, around 50 °C, where the DNA primers anneal or stick to the template strands, with each primer annealing to each strand. Lastly, in the DNA synthesis step, the temperature is raised to 72 °C, which is the optimal temperature for the heat-stable DNA polymerase to add nucleotides to the primer using the single-stranded target as a template. Repeating these cycles 25-40 times results in the amplification of the target DNA sequence by tens of millions to over a trillion.

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Answer:

2 % of NaCl concentration

The solution is hypertonic to human cells

Explanation:

% Concentration = (g solute / g solution) * 100

Therefore

% Concentration of NaCl = (2 g NaCl/ 100 g solution) * 100

The concentration of the solution equals 2 %

Isotonic solutions for human red cells have a concentration of 0.9 % of NaCl.  A concentration of 2 % of NaCl is above 0.9 %, so the solution is hypertonic, since you have more concentration of solute (NaCl) outside the cell, than inside the cell ( inside the side you have only 0.9 % NaCl). So the cell will shrink.

Answer:D

Explanation:

Answer: E

Explanation:

Answer:

True

Explanation:

Transgenic animals are lines of animals produced by inserting copies of a specific gene or genes into a fertilized egg or early embryo.

Answer: d. alternation of multicellular generations

Explanation:

The gametophytic as well as the sporophytic generations are alternative in the life cycle of the multicellular plants. This can be seen among the land plants. This feature cannot be seen in the algal species as they are unicellular in nature. Thus cannot be seen in the relatives of charophyta algae.

Alternation of multicellular generations is the characteristic of plants that is absent in their closest relatives, the charophyte algae.

Vascular plants have a haplodiplont biological cycle with antithetical alternation of generations, this means that there are only two generations that develop in different nuclear phases:

This cycle differs from the haplonte cycles where the generation or generations develop in the haplofase or from the diplontes when the generation or generations develop in the diplophase; these types of cycles occur in more primitive plants.

When more than one generation alternate within the same phase, it is called homogenesis, as opposed to antigensis (mentioned for higher plants) where there is only one generation in each phase.

However, among charophyte algae there is only isomorphic alternation in ulvophyceae; the rest, including caroficeas, have a haplonte cycle in which the zygote undergoes meiosis.

Therefore, we can conclude that alternation of multicellular generations is the characteristic of plants that is absent in their closest relatives, the charophyte algae.

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Answer:

Xylem function is to transport water and minerals.

phloem function is to transport food to different parts of plants.

Explanation:

We can Differentiate phloem from xylem by following ways

Answer:

e. all of these diseases can be transmitted in this manner

Explanation:

All the diseases mentioned above can be transmitted by water or food infected with human fecal material, so it is important to always know the origin of the foods that are consumed, as well as promote the cooking and efficient cleaning of these foods.

As stated above, these diseases can be transmitted by water contaminated by faecal material from a human who has the disease, this shows the importance of promoting a basic sanitation system in cities, so that everyone has a guarantee of clean and free water. of contaminants. It is also important to avoid bathing in rivers and lakes of suspicious places and always taking available vaccines to fight disease.

P.S.  vaccines do not cause health problems, on the contrary, they are designed to protect humans from possible parasites

Answer:

Release of oxygen. (Ans. C)

Explanation:

Calvin cycle is the set of chemical reaction which it takes place in chloroplast during photosynthesis. It is a light-independent cycle ( where carbon fixation occurs) because it takes place after the energy has been taken from sunlight. These are the steps includes in this cycle:

1) Calvin cycle adds carbon from CO2 present in the atmosphere to a 5 carbon molecule, known as ribulose bisphosphate catches 1 molecule of carbon dioxide and form a 6 carbon molecule.

2) The enzyme RuBisCo breaks the 6 carbon molecule into two equal parts with the energy of ATP and NADPH (oxidation of NADPH) molecules.

3) One trio of carbon molecule leave and become sugar and another trio of carbon molecule move to the next steps.

4) The 3 carbon molecule changing into a 5 carbon molecule, using ATP and NADPH (oxidation of NADPH), and the cycle starts over again.

The Calvin cycle is responsible for carbon fixation and the production of glucose during photosynthesis. It involves several reactions, but the release of oxygen does not occur during the Calvin cycle.

c is correct

The Calvin cycle is a series of chemical reactions that occur in the stroma of chloroplasts during photosynthesis. It is responsible for converting carbon dioxide into glucose, a process called carbon fixation. In the Calvin cycle, several reactions take place, including the oxidation of NADPH, the regeneration of the CO2 acceptor, and the synthesis of carbohydrate molecules from G3P using ATP and NADPH.

Out of the given options, the one that does not occur during the Calvin cycle is c. release of oxygen. In photosynthesis, the release of oxygen occurs during the light-dependent reactions, specifically in photosystem II.

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Answer:

There are prion-like particles in the brain normally, and when these become abnormal they can cause disease. (Ans. A)

Explanation:

Prions are proteins which can trigger normal proteins to fold abnormally, and they are present in the brain. They are causing many types of neurodegenerative diseases in both humans and animals. Which are known as transmissible spongiform encephalopathies.

Prions can enter the brain with the help of infection, also can arise from the gene mutation that encodes the proteins, and sometimes this affects humans by infected meat.

If a person infected from prion disease, it affects central nervous system tissues like brain, eye tissues and spinal cord.