In guinea pigs coat color is determined by a single gene with two alleles. A guinea pig from a true-breeding black strain is mated with a guinea pig from a true-breeding white strain. The F1 progeny are all black. Two of the F1 progeny are mated with each other. What proportion of the black F2 progeny is expected to be homozygous?

Answer:

The correct answers are option b. "replication bubbles" and d. "replication forks".

Explanation:

The nucleic acids replication systems share some similarities between eukaryotes and prokaryotes. For instance, both organism have replication bubbles. However, prokaryotes have a single replication bubble because its replication process starts from a single origin, while eukaryotes have several replication bubbles. Also, the replication forks are well conserved from prokaryotes to eukaryotes with only some differences among the enzymes present within the fork.

Answer:

NADPH dehydrogenase.

Explanation:

Electron transport chain may be defined as the sequential steps of transfer of electrons through the complexes and couple with proton gradient. The ATP is generated by the electron transport chain.

NADPH dehydrogenase is an ezymes that are used for the conversion of NADPH into NADH+. The NADH dehydrogenase is complex I of the electron transport chain. The NADPH dehydrogenase is not the enzymes complexes and not involved in the electron transport chain.

Thus, the correct answer is option (b).

Final answer:

The electron transport chain in mitochondria does not include NADPH dehydrogenase, which is instead associated with processes like photosynthesis. The other complexes listed are involved in the different steps of the mitochondrial electron transport chain.  So the correct option is a.

Explanation:

The subject of this question is the respiratory enzyme complexes involved in the electron transport chain, specifically which one is not part of this process. The correct answer to the question is b. NADPH dehydrogenase. The other options provided are indeed part of the electron transport chain, as follows:

NADPH dehydrogenase is not a component of the mitochondrial electron transport chain; rather, it is associated with other processes such as photosynthesis in plants.

Basically, a reading frame is the result of DNA or RNA nucleotide sequencing in non-overlapping triplets. It's like taking the strand of DNA and / or RNA and stretching it into a straight line. Thus, all nitrogenous bases would be in sequence and aligned as in a row. Each three nitrogenous bases (codon) encodes a protein.

The reading structure has revolutionized the field of genetics and evolution, since we can see the sequencing of the genes of individuals, we can make comparisons between their DNAs to discover possible evolutionary relationships between them. In addition, it is also very important in medicine to locate sequences where there are genetic mutations (base exchanges or subtractions).

Answer:

Explanation:

DNA is deoxyribose nucleic acid. It is a double helical structure. It remains in the coiled form so as to make the information stored in the small region within the cell. The sequence of bases allows the information to be stored in the coded form so as to promote the synthesis of proteins. Complementary base pairing allows the DNA molecule to replicate itself.

A controlled experiment is one that tests experimental and control groups in parallel, with all other variables kept constant. This enables the scientist to observe the impact of a single variable.

A controlled experiment is one that can be defined as an experimental set up in which the scientist keeps all variables constant, except for the one being studied. The correct option here would be option 'b'. Such an experiment tests experimental and control groups in parallel.

This methodology allows the researcher to observe the effect of one variable on the study subject while ensuring that all other conditions remain the same. For example, if you were to experiment with plant growth, you might keep factors like sunlight, water, and type of soil constant while changing the type of fertilizer used.

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Answer:

Molecular biology (DNA sampling) is the best proof.

Explanation:

An study published in the journal of science found that 99.9% of humans are quite similar. The  scientific team analysed DNA from 1,056 people from 52 populations in Africa, Eurasia (Europe, the Middle East, Central and South Asia), East Asia, Oceania and the Americas.

The phenotype ( visible appearance) results from a very small proportion of  differences in genetic traits, hence the concept "race" is more a cultural concept than a biological concept.

Answer:

Undifferentiated inner cell mass

Explanation:

Human embryo has two types of cells in its initial stage, trophoblast and inner cell mass.  Trophoblast forms the placenta and inner cell mass form the entire human body. Inner cell mass are pluripotent in nature i.e. they can give rise to any body part under right conditions.

Embryonic stem cells are derived from the inner cell mass. They are derived from pre implantation embryo since after implantation the inner cell mass begins to differentiate. Embryonic stem cells can replicate indefinitely without differentiating. They can give rise to all the three germ layers: ectoderm, mesoderm and endoderm. They can treat a number of disorders like genetic disorders, Parkinson's, spinal cord injury, cancers etc.

Answer:

The two DNA strands have anti parallel polarity which means that they are directional and anti parallel to each other. The polarity to these strands is conferred by the deoxyribose sugar molecule in nucleotide. The sugar molecule has 5 Carbon atoms. The third carbon is attached to an OH group and the fifth carbon is attached to a phosphate molecule. This asymmetry is responsible for giving DNA molecule a direction.

The double helix structure has both these strands in opposite direction so that the 5 prime carbon of one strand faces the 3 prime carbon of another. The anti parallel structure of DNA strands lets the base pairs complement each other. Anti parallel structure is also more stable than parallel structure.  

Answer:

(B) resemble structures formed by bacterial communities that are found today in some shallow marine bays.

Explanation:

Extant stromatolites represent real "living fossils" for they are decendents of ancient forms that are associated with one of the first living forms on earth. Particularly, stromatolites are real bacteria communities where the autotrophic organism of the community are represented by cyanobacteria, which live along with heterotrophic bacteria. This clearly indicates that fossilized stromatolites points to bacteria (prokaryotes) as the first living things on earth (dated with not less than 3.5 billion year old)

Nowadays, stromatolites with cyanobacteria allows to reconstruct and understand fossilized forms. These current structures live in shallow marines ambients (e.g. Australia) but also in continental salt flats (e.g. Argentina) where few others bacteria can survive to these extreme conditions (high light exposure and salt concentration).

Stromatolites are sedimentary formations created by cyanobacteria that resemble structures found today in some shallow marine bays. They provide key insight into early photosynthetic life on Earth.

Stromatolites are layered mounds, columns, and sheet-like sedimentary rocks that were originally formed by the growth of layer upon layer of certain cyanobacteria, a primitive form of photosynthetic life. Option (B) is correct - Stromatolites resemble structures formed by bacterial communities that are found today in some shallow marine bays. The cyanobacteria secrete a sticky substance to which sediment adheres, and if conditions are right and undisturbed by other organisms or strong currents, a new layer of cyanobacteria grows over it and the process repeats, leading to the formation of a fossilized layered structure.

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Answer:

The correct answer will be option-B.

Explanation:

The plant tissues are composed of three types of cells: parenchyma, collenchyma and sclerenchyma.

The parenchyma and collenchyma remain alive at their maturity but sclerenchyma loses their protoplasm and become dead. These cells deposit lignin in their secondary walls and form hard tissues of the plant-like hard shell of a coconut. Sclerenchyma provides mechanical strength to the plant.

Thus, Option-B is the correct answer.

Answer:

The correct answer is option B. Bufo Marinus.

Explanation:

The cane toad a american species of toads that is known as its scientific name Rhinella marina which is formerly known as Bufo Marinus. Commonly called neotropical toad which is large, land toad found in central and south America.

These toads are the world's largest toads that are known for their invasive properties as they grow and reproduce incredibly fast.

Thus, the correct answer is option B. Bufo Marinus.

Answer:

a. spontaneous mutations

Explanation:

Spontaneous mutations occur randomly in all cells and without any agents. Induced mutations are the result of some exposure to a physical or chemical agent called a mutagen. Mutations can be classified as harmful and adaptive regardless of whether they were spontaneous or induced mutations. The reversal mutation is when a given mutation is reversed by another mutation so that the nucleotide is changed back to its original state.

Answer:

The correct answer will be option-D.

Explanation:

In eukaryotes, the process of transcription takes place inside the nucleus whereas translation takes place in the cytosol. So, mRNA has to export to the cytosol from the nucleus.

Before export, the post-transcriptional modification takes place like 5' capping, 3' tailing and splicing mechanism.

The capping is done at 5' end by adding modified guanine (G) nucleotide which protects the mRNA from exonuclease activity and tailing is done at 3' end by adding adenine nucleotides which provides stability to the mRNA.Splicing removes the junk DNA called introns and joins the exons before export.

Thus, option-D is the correct answer.

The incorrect statement about eukaryotic mRNA processing is 'a 3' cap and a 5' poly(A) tail must be added.' In actuality, a 5' cap is added and a 3' poly(A) tail is added.

The statement that is not correct about eukaryotic mRNA processing is: 'd. a 3' cap and a 5' poly(A) tail must be added.'

In eukaryotic mRNA processing, there are several modifications made. Firstly, a 5' cap is added to the beginning of the mRNA molecule, not a 3' cap. Additionally, a poly(A) tail is added at the 3' end, not the 5' end. Therefore, option 'd' is incorrect. The rest of the modifications, which include the removal of introns, the export of the mRNA transcript from the nucleus, and the splicing together of exons to form the final mRNA transcript, are correct.

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Eukaryotic

Cells with a differentiated nucleus that contains all the DNA, limited by nucleus membrane, and has a cytoplasm limited with the plasma membrane that contains organelles.

The ribosomes are bigger, 80 S (svedbeg is the measuring unit)

Procaryotic

All its genetic material spread on the cytoplasm.

This kind of cell does not have organelles. All biologic processes made in specific places in the plasma membrane.

The ribosomes are smaller, 70 S.

Mitochondria

It's an organelle you can find inside a eukaryotic cell.

It has two membranes, one outsider, and one insider.

The insider one has folded.

Scientific believe that millions of years ago, the mitochondria was a bacteria and the eukaryotic cell phagocyte it and became part of it.

The ribosomes are the same size that procaryotic cells.

Answer:

c. protein from RNA

Explanation:

Translation is a process that occurs in the ribosomes where tRNA is used to read the mRNA strand and translate the codons into complementary amino acids.

Answer: The new daughter cells will have an abnormal amount of genetic material. That is called aneuploidy and it is the presence of an abnormal number of chromosomes. Different clinical conditions are the result of this nondisjunction.

Explanation:

Normal cells are diploids, that means they have two copies of each gene, one of each chromosome. So normal cells have two homologous chromosomes, one from each parent.

During anaphase of cell division, each pair of chromosomes is separated  by the mitotic spindle. The separated chromosomes are then pulled by the spindle to opposite poles of the cell, and eventually will end up in the new daughter cells.

Nondisjunction is the failure of homologous chromosomes to separate properly during cell division, so it is the miss segregation of them. The new daughter cells will have an abnormal amount of genetic material. Different clinical conditions are the result of this nondisjunction.

Sex chromosomes participates in sex determination of an individual. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY) So nondisjunction of sex chromosomes could be:

According to which gametes are fused during fertilization, different phenotypes can be given. For example, if a gamete with one chromosome fuses with another gamete with two chromosomes, the result will be an individual with three chromosomes (it could be XXY, or XXX) called trisomy.

Triple X syndrome is characterized by an extra X chromosome in females. Those affected are often taller than average, but most females have a normal sexual development. Klinefelter syndrome is known XXY individuals, and it causes infertility in males, breast growth, less body hair and weaker muscles.

And if a gamete with no chromosome fuses also with another gamete with no chromosome, the result is a nullisomy. But due to the lack of genetic material, the nullisomic gametes are rendered unviable for fertilization.

And if a gamete with no chromosome fuses with another gamete with one chromosome (normal) the result is a monosomy, the presence of only one chromosome from a pair. The result can be an individual who is X or Y. People with Turner syndrome have one X chromosome and it is the only monosomy that is seen in humans because other cases monosomy are lethal.

Any of those examples is called aneuploidy and it is the presence of an abnormal number of chromosomes.

Answer:

The correct answer is option b, that is, flight.

Explanation:

Our atmosphere is comparatively thick, and it possesses the tendency of supporting the creatures, which are light. The factual flight, however, relies upon the fact that whether an individual is sufficiently light, and is equipped with appropriate characteristics, and has a desire to make a since the attempt to make aloft.  

The birds are the most apparent fliers in the world we live in. The first bird appeared in the fossil about sixty-five million years ago. Like birds, bats also have developed an elegant approach to flight. Similarly to birds, they exhibit lightweight and slender bones, and a compact skeleton, and have developed strong muscles for flapping flight.  

Final answer:

b) Flight is the trait that evolved multiple times in vertebrates, with different species developing unique wing structures through convergent evolution.

Explanation:

The trait that evolved multiple times over the course of the evolution of vertebrates is flight. Flight has evolved independently in different vertebrate lineages through a process known as convergent evolution. This is evident in the wings of pterodactyls, birds, and bats, which are structures adapted for the purpose of flight, but each has a unique anatomical development despite the forelimbs being homologous structures. On the other hand, hair has evolved only in the lineage leading to mammals, and oviparity, though widespread, is not an example of multiple independent evolutionary events. Homodonty, the condition of having teeth uniform in shape, may have appeared in different lineages but is not as clear an example of repeated evolution as flight. The development of traits like a high metabolism, a four-chambered heart, and other modifications have supported the evolution of flight in vertebrates.

Answer:

Degenerate.

Explanation:

Genetic code may be defined as the codons of three nucleotides that can be inherited to the next generation. The codons codes for the particular amino acids.

The degeneracy of the genetic code means the a single amino acids is coded by more then one codons. For example: Leucine is coded by UUG as well as UUA.

Thus, the correct answer is option (b).

Answer:

In our respiratory system, there is a pair of external nostril situated above the upper lip that receives atmospheric air and passed to the pharynx (a common passage for air and food). The pharynx passed this air to the trachea via larynx (known as the soundbox). The trachea is an extended part which is divided into left and right primary bronchi. Bronchi divide into secondary bronchi, tertiary bronchi, and bronchioles that ending up in thin terminal bronchioles. Each terminal bronchiole constitutes a number of irregular-walled, thin and vascularised bag-like structures called alveoli which are the primary sites of gases exchange.

Answer:

The correct answer will be option-C.

Explanation:

Hypothalamus is a part of the brain which controls many important functions of the body by producing hormones.

When the amount of water gets reduced in the blood, it leads to a change in the osmolarity which can be easily detected by the osmorecpetors present in the neurons of the hypothalamus.

In response, neurons secrete Anti-diuretic hormone in the blood which acts in the tubules of the kidney where they help in re-absorption of the water from the body.

Thus, Option-C is the correct answer.

Answer:

The correct answer will be options-A and D.

Explanation:

Photosynthesis is a complex process which forms the glucose, the energy molecule of the plant. Photosynthesis takes place in the two phases: light-dependent reaction and light-independent reactions.

The light-dependent reaction leads to the breakdown of the water molecule which produces oxygen whereas in light-independent reaction, the carbon dioxide gets fixed during the carboxylation step of cycle utilizing the carbon dioxide.

Therefore, if photosynthesis takes place then it will lead to a rise in the level of oxygen and reduction in the amount of carbon dioxide.  Thus, options-A and D are the correct answer.

During photosynthesis, plants use carbon dioxide to create glucose and release oxygen. Hence, O2 levels rise, and CO2 levels fall.

In the process of photosynthesis, plants use sunlight to convert water and carbon dioxide (CO2) into glucose and oxygen (O2). Thus, during photosynthesis, you can expect that the levels of carbon dioxide (CO2) will fall as it is being used up, and the levels of oxygen (O2) will rise as it is being produced. So, the correct choices would be: a. O2 levels will rise, and d. CO2 levels will fall.

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Answer:

Water carries several physical properties such as chemical formula, appearance, boiling point, freezing point, density, viscosity and solvency.

An increase in temperature changes the density of water. When a water is heated or its temperature is allowed to increase it causes the water molecules to gain energy and move faster, which results in increase in water volume due to movement of water molecule far from each other. on the other side if temperature of water is decrease, it's molecules come closer to each other and decrease in the volume of water takes place.

Answer:

c. The molecule responsible for making the blue color is RNA.

Explanation:

Tube (a): DNA, RNA and proteins present ⇒ BLUE

Tube (b): DNA and RNA present ⇒ BLUE

Tube (c): DNA and proteins present ⇒ COLORLESS

Tube (d): RNA and proteins present ⇒ BLUE

RNA is the only molecule that is present every time the chamical is added and the tubes turn blue, and not present when the color doesn't change, meaning in tube (c) there's no reaction with the added chemical.

In conclusion, RNA is the only molecule reacting with the chemical and responsible for blue appearance.

Answer:

The given statement is true.

Explanation:

In the nuclei atoms we know that there are 2 type of particles named protons and neutrons.As we know that  the neutrons are uncharged and protons are positively charged thus in such a close proximity when the proton's are just touching each other the electrostatic forces of repulsion between the particles becomes exceedingly large thus rendering the nucleus theoretically unstable. But as we know that the nucleus is inherently stable indicating that there is another type of force that must act between the nucleons (proton's and neutrons) this fundamental force is known as strong nuclear force and is the strongest force among the 4 fundamental forces in nature.

Answer:

true

Explanation:

hope it helped

Answer:

The correct answer is b. False

Explanation:

More than 90% of bacteria present in the world is not harmful to human beings. Human body contains trillions of bacteria in their intestine which play important role digestion of food absorption of nutrients inside the small intestine.

Human gut contains 10 times more bacteria than the cells present in human body. This proves that bacteria lives in symbiotic association with humans and human body cannot survive without them.

Thus a large percentage of bacteria are not harmful to humans rather they are important part of human body and these bacteria are called human microbiota.

The correct answer is E. 0

Explanation:

The deciduous dentition or baby teeth refer to the first set of teeth human have before the permanent teeth, these teeth are prevalent during infancy and include 20 teeth: 4 central incisors, 4 lateral incisors, 4 canines and 8 molars divided into 4 primary molars and 4 secondary ones. In the case of premolars, these are part of permanent teeth but not of deciduous teeth as they only appear after deciduous teeth begin being replaced and these replace the molars in deciduous dentition. Thus, the number of premolars in deciduous dentition in humans is 0.

Answer:

To reduce thiol-groups of the protein

Explanation:

Dithiothreitol of b-mercaptoethanol act as reducing agents. Including them in a buffer would prevent oxidation of thiol-groups in amino acids of the protein and preventing its denaturation.

Answer: B) Cell Division

Explanation: Cancer is the rapid division of cells. It comes in many forms (Eg: Brain Cancer, Breast Cancer) and can be deadly.

Answer:

The correct option is: B. Contraceptive diaphragm

Explanation:

Contraception, also known as birth control, are the various methods like barrier methods, hormonal contraception, sterilization, intrauterine devices, and behavioral methods, that are used to prevent pregnancy.

The hormonal method of contraception includes vaginal rings, injections, patches and oral contraceptive pills. This contraceptive method involves the use of steroid hormones- estrogen, progestin, and progesterone.

Whereas, the barrier method of contraception includes condoms, contraceptive sponges, diaphragms and the fertility awareness methods.

Therefore, contraceptive diaphragm is not a hormonal method of contraception.