Answer:
Gene mutation:
Gene mutation may be defined as change or alteration in the nucleotide sequence of the gene. DNA replication errors and mutagens are responsible for the gene mutation. A single gene may affected in this mutation. For example: Sickle cell anemia is caused by the replacement of GAG to GUG results in the formation of valine instead of glutamic acid. The shape of RBCs changed from the biconcave to the sickle cell shape.
Chromosome mutation:
Chromosome mutation may be defined as the change or the alteration of chromosome number or structure. Chromosome mutation occurs due to errors during crossing over. The segment of the chromosome may get changed. Large number of genes may get affected. For example: Down syndrome occurs due to the presence of extra chromosome at chromosome 21.
Which of the following can contribute to infertility in a young male body builder taking anabolic steroids?
a. suppression of LH release from the pituitary
b. decreased circulating levels of dihydrotestosterone (DHT)
c. increased muscle mass
d. decreased testicular testosterone concentrations
e. B and D
Answer:
The correct answer is a. suppression of LH release from the pituitary.
Explanation:
Anabolic steroids are synthetic steroids made up of mainly androgenic hormone like testosterone. These anabolic steroids are usually taken by young male bodybuilders because it helps in gaining muscles.
These anabolic steroids have many side effects and infertility in males is one of its side effects. Excessive use of these steroids stops the secretion of gonadotropic hormones such as LH in males from pituitary glands by inducing negative feedback to the pituitary.
LH is important in the production of testosterone from Leydig cells and testosterone is important for sperm production. Therefore if LH is stopped no sperm production will occur and it leads to infertility in males.
Briefly, in two to three sentences, contract the functions of innate, humoral, and cell-mediated immunity.
Answer:
Innate immunity includes non-specific immune responses to prevent the entry of pathogens and to kill the entered pathogen by first line of defenses.
Humoral immunity kills the entered pathogens by production of antibodies specific to the particular type of antigen. B lymphocytes are central to the humoral immunity.
Cell mediated immunity is another type of adaptive immune response wherein the killer T cells directly kill the infected cells.
Explanation:
Cell-mediated immunity is provided by killer T cells against virus-infected cells, foreign cells, and cancer cells. The cytotoxic T cells directly kill the entered pathogens.
Antibody-mediated immunity refers to the specific resistance to disease-causing agents. It includes the production of specific antibodies by B lymphocytes. it is also called humoral immunity.
Innate immune responses are the nonspecific immune responses that prevent the entry of all the diseases causing pathogens and antigens into the body. It includes the first line of defenses such as skin and mucous membranes as well as phagocytes and natural killer cells that kill all the pathogens and antigens non-specifically.
How is a spider web like a food chain?
Answer:
food webs are drawn in a diagram similar to a spider web
The enzyme helicase unwinds the DNA duplex. Which of the following is likely to be true?
A) A pre-existing 3'OH is required for helicase to work
B) Helicase uses energy from ATP Hydrolysis
C) Helicase is itself made of RNA
D) Energy is released when the DNA helix is unwound.
Answer:
B) Helicase uses energy from ATP Hydrolysis
Explanation:
Helicase's primary function is to separate the annealed nucleic acid strands. It is a motor protein and moves directionally along the phosphodiester backbone. It usually separates strands of double helix DNA or self annealed RNA. It used the energy from ATP hydrolysis and breaks hydrogen bonds between nucleotide bases.
In human body 95 types of helicases are found. They have sequence motifs required for ATP binding, ATP hydrolysis and translocation along nucleic acid phosphodiester backbone. The variable portion in their amino acid sequence imparts specific feature to each helicase.
Assume that the structural genes of the lac operon have been fused, through recombinant DNA techniques, to the regulatory apparatus of the ara operon. If arabinose is provided in a minimal medium to E. coli carrying this gene fusion, would you expect β-galactosidase to be produced at induced levels? Why?
Answer:
The correct answer is "Yes, β-galactosidase would be produced at induced levels".
Explanation:
The L-arabinose operon, also known as ara operon, is activated in the absence of glucose and in the presence of arabinose. In this study the ara operon was fused with the lac operon, therefore arabinose would active not only the genes of ara operon but also lac operon. Once the researchers provide E. coli with arabinose, the bacteria would produce β-galactosidase as a result of lac operon activation.
When a large number of species, sometimes entire major taxa, go extinct in a short period of time on the geological scale, the cause is usually
A. Competition with other species
B. A large forest fire
C. Radical global climate change
D. Predation by a new type of hunter
Answer: C. Radical global climate change.
Explanation:
The entire taxa of the species can be wiped out due to an large catastrophic event associated with the change in the climate. As the climate becomes warm the chances of undergoing the global precipitation rate will change. The climate being an important abiotic factor under unstability is likely to affect the amount of rainfall, snow fall, drought and conditions of desertification. All these factors can be responsible for the removal of the entire taxa of the species in short time.
The underlying structure of DNA is very simple, consisting of only four possible building blocks. a. How is it possible for DNA to carry complex genetic information if its structure is so simple? b. What are these building blocks? Can each block be subdivided into smaller units, and if so, what are they? What kinds of chemical bonds link the building blocks? c. How does the underlying structure of RNA differ from that of DNA?
Answer and Explanation:
a) Although the DNA is made up of only four possible building blocks, these blocks are combined from a 3 (form triplets of nitrogenous bases) giving rise to a large variety of nucleotide sequences that carry a large amount of genetic information.
b) DNA is a polymer formed by nucleotides, which we could consider as the building blocks.
Each of these nucleotides is, at the same time, formed by a carbohydrate, a nitrogenous base and a phosphate group (derived from phosphoric acid). The nitrogen base may be adenine (A), thymine (T), cytosine (C) or guanine (G).
The nitrogenous bases are located in a complementary manner between the two strands of DNA, with thymine-adenine being joined by a double bridge of hydrogen and cytosine-guanine by three hydrogen bonds.
Example of questions A and B: AAA, AAT, AAC, AAG, ATT, ACC, AGG, ATA, ACA, AGA, etc.
c) In RNA the carbohydrate that is present is ribonucleic acid while in DNA it is deoxyribonucleic acid.
In addition, in the RNA, the thymine nitrogenous base is replaced by the Uracil.
Why is the Earth's crust composed of 'lighter' elements than the mantle or core?
Answer:
True, earth's upper crust that is lithosphere is made of lightweight rocks and is thinner as compared to that of the rock that are found in the below layers.
Explanation:
The outer layer covering the planet is made up of lighter and less dense rock as this layer is called the plating layer or the crustal rock layer which is composed of silicon 27.7% and aluminum 8.1 %, Iron 5.0% and Oxygen 46.6% and having light-matter has 1 % of the entire landmass. Being composed of all types of rocks like sedimentary, metamorphic and igneous rocks. The crust is either oceanic or continental as the continental being the landmass is light and consists of only 29% of the entire earth some area partly submerged. Depth of 700 km. Mantel being the second, layer is composed of heavier elements like the Magnesium, Iron and other dominant metals has an average thickness of 2900 km constitutes 70% of earth mass. Divided into three layers upper, lower and Transition, etc. The outer core starts from 5150 kilometers to 6370 kilometers from outer to inner containing iron, nickel, and sulfur and followed by the transition in between presence due to the liquid boundaries, intensity gravity, and pressure.The Earth's crust consists of lighter elements because during Earth's formative, molten state, elements with lower densities floated toward the surface, while heavier elements sank, forming the denser core and mantle.
Explanation:The Earth's crust is composed of lighter elements than the mantle or core due to the process known as planetary differentiation. When Earth was molten during its formation, materials with different densities separated under the force of gravity. The heavier elements, such as iron and nickel, sank to the center to form the core, while the lighter elements, like silicon, oxygen, and aluminum, floated towards the surface, forming the crust.
The crust is broken up into two main types: oceanic and continental crust. Oceanic crust is denser and predominantly made of basalt, whereas continental crust is composed largely of granite, which is less dense. As a result of these processes, the crust is much less dense than the mantle, which is made of solid but deformable rock, and the core, which has the highest density due to its metal composition.
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During light reactions, ATP is produced when hydrogen ions move:
a. Down their concentration from the stroma into the thylakoid space
b. Against their concentration gradient from the stroma to the thylakoid space
c. Down their concentration gradient from the thylakoid space into the stroma
d. Against their concentration gradient from the thylakoid into the stroma
Answer:
The correct answer will be option-C.
Explanation:
Light-dependent reactions are the reaction of photosynthesis which takes place in the presence of light.
During light reaction, ATP and NADPH intermediates are produced which are utilized during the light-independent reaction. The main reactions that take place during light reactions are photolysis of water and ATP synthesis due to the electron transport chain.
Electron transport chain generates electrochemical gradient across the thylakoid membrane sue to the accumulation of protons in the thylakoid lumen and fewer protons in the stroma of the chloroplast.
This causes the osmotic movement of protons down their concentration gradient through ATP synthase. The movement if hydrogen ions take place from thylakoid lumen to stroma forming ATP molecules.
Thus, Option-C is the correct answer.
ATP is produced during the light reactions of photosynthesis when hydrogen ions move down their concentration gradient from the thylakoid space into the stroma, a process facilitated by ATP synthase.
Explanation:During the light reactions of photosynthesis, ATP is produced when hydrogen ions move down their concentration gradient from the thylakoid space into the stroma. This is a process known as chemiosmosis, which harnesses the passive diffusion of hydrogen ions from a high concentration within the thylakoid lumen to a lower concentration in the stroma. This movement of hydrogen ions through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate.
The correct answer to the question is:
c. Down their concentration gradient from the thylakoid space into the stroma
In October of 2002, General Mills Inc. recalled over 4,000 cans of refried beans suspected to be contaminated with Clostridium botulinum. Which of the following statements regarding adult botulism is correct?
a. the anaerobic environment of the sealed can provides a suitable environment for the spores to germinate.
b. the spores produce a potent neurotoxin
c. symptoms of the disease are stiff, contracted muscles, such as "lockjaw", and eventual paralysis of the respiratory muscles, which results in death
d. reheating the beans to kill the bacteria will prevent the disease.
e. all of the above statements are correct
Answer:
A and B
Explanation:
A and B are correct answers.
C is incorrect because Botulism does not produce stiff muscle, in fact it produces flaccid paralysis. Stiff muscles and lockjaw is produced by C. Tetani.
D is somewhat incorrect because, although you can kill the toxins via heat, you would need to heat your food to over 100°C for around 10 minutes, which no one does. Thus, reheating beans would not protect you from the bacteria and/or its toxins.
What kind of bonds connect the bases of DNA to each other?
a. ionic
b. hydrogen
c. covalent
d. van der Waals
e. protonic
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. Each monomer is made up of a five-carbon deoxyribose sugar, a phosphate group and four different nitrogenous bases.
The nitrogenous bases- purines (adenine and guanine) bond with pyrimidines (cytosine and thymine) via hydrogen bond between them. The hydrogen bonds are weak bonds but establish the DNA structure.
Thus, Option-B is the correct answer.
The bases of DNA are connected by hydrogen bonds.
Explanation:The bases of DNA are connected to each other by hydrogen bonds. These bonds form between specific complementary base pairs: adenine (A) with thymine (T) and guanine (G) with cytosine (C). Hydrogen bonds are relatively weak compared to covalent bonds, but they are crucial for maintaining the structure of the DNA helix.
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Explain how the independent alignment of homologs, and also crossing-over during the first meiotic division, each contribute to the genetic diversity of gametes.
Answer: Homologous chromosomes are randomly distributed to daughter cells, this means different chromosomes segregate independently of each other. And they exchange segments of DNA during crossing over. This recombination creates genetic diversity because genes from each parent are exchanged.
Explanation:
Meiosis is a type of cell division that produces gamete cells, which are sex cells (egg and sperm)
Chromosomes that form a pair and are found together are called homologous chromosomes, and they are inherited from each parent. During prophase of meiosis I, the homologous chromosomes exchange segments of DNA in a process called crossing over. This recombination creates genetic diversity because genes from each parent are exchanged. It results in new combinations of genes on each chromosome.
After that, during the anaphase of meiosis I, the two chromosomes line up on the equatorial plane of the cell. Then, they are separated and each will go to a new daughter cell. So homologous chromosomes are randomly distributed to daughter cells, this means different chromosomes segregate independently of each other.
Explain why cytotoxic T cells are not affective against bacteria.
Answer:
Because cytotoxic T cells are activated with antigens.
Explanation:
Cytotoxic T cells are a type of white blood cell that expresses T-cell receptors that can recognize specific antigens to then be activated by them to neutralize an infected cell, antigens are structures that can stimulate an immune response, they are presented by the cells so T cells can identify them.
So, based on the previous information, cytotoxic T cells can't recognize or attack bacterias if their T cell receptors don't have an antigen presented by another cell to bind.
I hope this information clarifies your doubts!
Which process is most directly driven by light energy?
(A) creation of a pH gradient by pumping protons across the thylakoid membrane
(B) reduction of NADP+ molecules
(C) transfer of energy from pigment molecule to pigment molecule
(D) ATP synthesis
Answer:
C
Explanation:
The energy from sunlight is used to split water molecule into H+ and O- and the emanating electron used to replace the lost electron at the reactive center of the Photosystem I & II. The lost electron is a high energy electron that is transferred from pigment to pigment in the Photosystem. As it does, its energy is harnessed and used to pump H+ protons into the lumen of the thylakoid from the stroma (creating a proton motive force that will be used to make ATPs). Ultimately this electron will then reduce NADP to NADPH.
The process that is most directly driven by light energy is ; ( C ) Transfer of energy from pigment molecule to pigment molecule
The light energy derived from the sunlight or a corresponding light source splits the H⁺ and O⁻ contained in water molecules. The split O⁻ replaces the electron which is lost at the center of photosystem I and II.
The lost electron at the reactive center contains energy while it is been transferred from one pigment molecule to another pigment molecule and this driven directly by the light energy.
Hence we can conclude that the process that is most directly driven by light energy is Transfer of energy from pigment molecule to pigment molecule.
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Starch is broken down into ____________ by the enzyme ___________
Starch is broken down into maltose by the enzyme amylase. Maltose is then further hydrolyzed into glucose by the enzyme maltase, primarily in the small intestine.
Starch is broken down into maltose by the enzyme amylase. Initially, starch is hydrolyzed by salivary amylase in the mouth and later by pancreatic amylase in the small intestine, producing shorter polysaccharides, dextrins, and disaccharides like maltose. These smaller sugars are easier for the body to absorb. Following this, the enzyme maltase, which is produced by the cells in the small intestine, further breaks down maltose into individual glucose molecules, which are used by the body for energy.
Describe four reasons why eukaryotic reproduction is more complex than prokaryotic reproduction.
Answer:
Explanation:
1. In prokaryotes , the reproduction takes place by asexual means such as binary fission whereas in eukaryotes the reproduction takes place by sexual means.
2. In eukaryotes mates are required which allows the fusion of males and female gametes, whereas in prokaryotes no mates are required offspring produce from single parent.
3. In prokaryotes many offspring produce from a single parent whereas in eukaryotes only few offspring are produced.
4. Growth of offspring development is complex in eukaryotes whereas the offspring development is simple in prokaryotes.
Final answer:
Eukaryotic reproduction is more complex than prokaryotic due to the presence of membrane-bound organelles, a larger and more complex genome with multiple linear chromosomes, a detailed process of cell division called mitosis, and a slower replication rate requiring tight regulation.
Explanation:
Eukaryotic reproduction is more complex than prokaryotic reproduction for several key reasons.
Eukaryotic cells have numerous internal membrane-bound organelles, such as mitochondria and chloroplasts, that need to be replicated and properly distributed during cell division.The eukaryotic genome is far more intricate and larger, with eukaryotes housing multiple linear chromosomes and up to 100,000 origins of replication. This creates a more complex replication process compared to prokaryotes, which have a single circular chromosome.Eukaryotes undergo a detailed and orderly process of cell division known as mitosis, with distinct phases such as prophase, metaphase, anaphase, and telophase, each with specific and vital roles in the successful division of the cell.The rate of replication in eukaryotes is slower than in prokaryotes, about 100 nucleotides per second, creating a longer, more intricate process requiring tight regulation and coordination.Alkaline pancreatic juices work in ___________
a. chemical digestion
b. neutralize pepsin
c. neutralize acid chyme
d. remove HCL
Answer:
The correct answer will be Option-C.
Explanation:
The pancreas is an organ which plays an important role in the digestion of the food. Pancreatic juice is secreted by the pancreas which contains digestive enzymes as well as the sodium bicarbonate (base).
The sodium bicarbonate is required for the digestion of the food as after the acidic digestion of the food in the stomach, the food chyme enters small intestine. The inner lumpen is not structured to handle the acidic chyme so sodium bicarbonate neutralizes the acid chyme that entered the lumen of the small intestine.
Thus, Option-C is the correct answer.
Pea seed color exists as green or yellow. We might say that "yellow" is an example of a (an)_ for seed color
a. genotype
b. allele
c. karyotype
d. homozygote
e. heterozygote
Answer:
b. allele
Explanation:
An allele is a variant form of a gene. In this problem, there is one gene (that determines seed color) with two possible alleles (green and yellow).
The other options are wrong because:
The genotype is the combination of alleles an individual has.
The karyotype is an individual's collection of chromosomes, paired and ordered.
A homozygote individual has the same alleles for a particular gene.
A heterozygote individual has different alleles for a particular gene.
The Cortisol Receptor once activated turns on genes. Explain how this protein accomplishes this activity.
Answer:
The cortisol is generally nothing but a hormone of a steroid category, which is produced by the adrenal glands as a reciprocation to any type of stress or low concentrations of glucose in the blood, also called glucocorticoid. It plays an essential role in all the vertebrates as it is accountable for conducting various activities associated with the metabolism, cardiovascular system, homeostasis, and immunity.
The glucocorticoid receptors or the cortisol receptors are found to take place in the cytoplasm and carry the heat shock proteins alongside. When the hormone reaches these receptors and combines with them some modification in their conformation takes place, and two things occur, that is, the heat shock proteins are discharged, and a complex is produced by the hormone and the receptor, known as the G. R complex.
This complex exhibits the tendency to move into the cytoplasm and performs the process of translation and transcription by combining it with the DNA. Here, it again can do two kinds of activities, that is, via transactivation it can result in the expression of the inflammatory proteins in the cytoplasm or via transrepression, it can repress the similar proteins.
Banana plants, which are triploid, are seedless and therefore sterile. Propose a possible explanation.
Answer:
The correct answer will be- homologous chromosomes fail to pair.
Explanation:
The seedless variety of the banana are triploid that is each cell contains three copies of the chromosomes. The triploid variety of the organism is considered sterile or not able to produce offspring as they are unable to generate gametes for fertilization.
The formation of gametes relies upon a type of cell division called meiosis which proceeds in four phases of karyokinesis stage.
At metaphase of the meiosis, chromosomes fail to pair at the equatorial plate as two chromosomes pair leaving one extra chromosome which is not paired. The gametes are produced with unequal chromosomes and on fertilization zygote is not formed.
Thus, homologous chromosomes fail to pair is the correct answer.
The genetic information contained in DNA consists of a linear sequence of coding units, known as codons. Each codon consists of three adjacent DNA nucleotides that correspond to a single amino acid in a protein. The E. coli DNA molecule contains 4.70×1064.70×106 base pairs. Determine the number of codons that can be present in this DNA molecule.
Answer:
The correct answer is 1.57 × 10⁶ codons.
Explanation:
It is given that the number of base pairs in E.coli DNA is 4.70 × 10⁶
1 codon = 3 DNA nucleotide adjacent that codes for a single amino acid
The number of bases or nucleotides in a single strand = number of base pairs in DNA = 4.70 × 10⁶
We only have to consider the coding strands triplet codons, that is,
Number of triplet codon = 4.70 × 10⁶ / 3
= 1.57 × 10⁶ codons.
Write a one page note on sex linked inheritance with 2 examples briefly explained.
Answer:
Sex linked inheritance may be defined as the type of inheritance in which the trait or mutation is present on X chromosomes rather than on autosomes. Sex linked trait expression will depend upon the type of sex.
Two type of inheritance of sex linked trait are X linked dominant and X linked recessive trait. In X linked recessive trait, the male are more affected as they have only single X chromosome. Females should have both X chromosome affected for the expression of the trait. In sex linked dominant trait, a single X chromosome is enough for the expression of trait.
For example: Color blindness is an sex linked recessive trait, the mother generally passes the trait to their sons. Fragile X syndrome is a sex linked dominant trait in which the affected father will have all the affected daughter.
What is the difference between cardiac and skeletal muscle cells?
Answer:
-The skeletal muscle has long and cylindrical cells. The cardiac muscle cells are short and together they form a branch.
-The heart muscle fibers have only one nucleus in the center. The skeletal muscle fibers are multinucleated.
-The skeletal muscle is voluntary and the cardiac is involuntary.
- Sarcoplasma and glycogen are more abundant in the heart muscle.
-The cardiac muscle is longitudinal striated and the skeletal is transverse striated
Make connections Which chemical group is most likely to be responsible for an organic molecule behaving as a base (see Concept 3.3)?
a. hydroxyl
b. carbonyl
c. amino
d. phosphate
Answer:
The correct answer will be option-C.
Explanation:
The functional groups are the group of atoms which gets attached to the skeleton of carbon in a molecule and provides certain characteristics to the molecule. The main functional group includes hydroxyl, carboxyl, amino, phosphate, methyl carbonyl and sulfhydryl.
These groups could be acidic or basic depending upon them if their structure will be able to take H⁺ ions from solution or donate H⁺ ions. In the given question, the basic group among these is an amino group which has the ability to accept H⁺ ions from the solution and form NH₃⁺ ions.
Thus, Option-C is the correct answer.
Calculate the volume of buffer to which 500mL of 60 mM potassium chloride solution must be diluted to make a new concentration of 0.001M.
Answer:
[tex]30,000[/tex] mL
Explanation:
Given -
Volume of buffer [tex]= 500[/tex] mL
Concentration of solution [tex]= 60[/tex] mM[tex]= 0.06[/tex]M
New concentration of the solution [tex]= 0.001[/tex]M
As we know
[tex]C_1* V_1= C_2*V_2[/tex]
Where
[tex]C_1, C_2[/tex] are the concentration of the solution before and after dilution.
And [tex]V_1, V_2[/tex] are the volume of solution before and after dilution.
Substituting the given values in above equation, we get -
[tex]500* 0.06 = V_2* 0.001\\V_2 = \frac{30}{0.001} \\V_2 = 30,000[/tex]mL
Which of the following statements accurately describes specific bacterial cell walls? View Available Hint(s) Which of the following statements accurately describes specific bacterial cell walls? Gram-negative bacterial cell walls contain teichoic acids, whereas the cell walls of gram-positive bacteria do not. The cell walls of gram-negative bacteria contain many more layers of peptidoglycan than those of gram-positive bacteria. In gram-negative bacteria, the thin layer of peptidoglycan is surrounded by an outer membrane made of phospholipids, lipopolysaccharides, and proteins. In bacteria with acid-fast cell walls, the carboxylic acid in the walls forms a layer outside a thin layer of hydrophilic polypeptides.
Answer:
In gram-negative bacteria, the thin layer of peptidoglycan is surrounded by an outer membrane made of phospholipids, lipopolysaccharides, and proteins. This statement accurately describes specific bacterial cell walls.
Explanation:
The Gram- negative bacteria constitute of an outer membrane which is richly made up of lipopolysaccharides, phopholipids and proteins. The lipopolysaccharides function mainly as a virulence factor and are involved in causing variety of diseases in animals.
Gram- negative bacteria can be seperated from gram- positive bacteria mainly because of the thickness of peptidoglycan and by the presence of the outer membrane of Gram- negative bacteria. The outer membrane is absent in Gram- positive bacteria.
Gram-positive bacteria possess a thick peptidoglycan layer anchored by lipoteichoic acid, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane with lipopolysaccharides and proteins, including porins.
Explanation:The question pertains to distinguishing between Gram-positive and Gram-negative bacteria based on their cell wall structure. The correct statement regarding these bacterial cell walls is that Gram-positive bacteria have a cell wall anchored to the cell membrane by lipoteichoic acid, which contains a thick layer of peptidoglycan and teichoic acids. In contrast, the outer membrane of gram-negative bacteria is composed of proteins, lipopolysaccharides, and phospholipids, and it is encircled by a thin layer of peptidoglycan. Porins, which are proteins that allow substances to pass through, are present only in the outer membrane of Gram-negative bacteria; they are not found in Gram-positive bacteria.
Additionally, unlike Gram-positive bacteria, Gram-negative bacteria do not contain teichoic acids in their cell walls. The inner membrane, a thin layer of peptidoglycan, and an outer membrane containing lipopolysaccharide define the cytoplasm of Gram-negative bacteria. This outer membrane and the associated structures account for the complex Gram stain reaction observed with Gram-negative bacteria as compared to the simpler cell wall of Gram-positive bacteria.
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Which of the following occurs during the light-dependent reactions of plants?
a. Electron transport
b. The splitting of water
c. A hydrogen ion gradient is established to produce AT
d. All the above
Answer:
The correct answer will be option-D.
Explanation:
Photosynthesis proceeds in two stages: light-dependent and light-independent reaction.
The light-dependent begins when the chlorophyll pigment of the photosystem absorbs light energy. This absorption causes the excitation of the electrons provided by the chlorophyll molecule.
The excited electrons accepted by electron acceptor molecule from reaction center and a chain of electron flow begin called electron transport chain.
This transport of electrons creates a scarcity of electron in photosystem which causes splitting of the water molecule as a result of which oxygen gas is released.
Thus, option-D is the correct answer.
Final answer:
All of the options given (electron transport, the splitting of water, and establishing a hydrogen ion gradient to produce ATP) occur during the light-dependent reactions of photosynthesis, which takes place in the chloroplast thylakoids of plants.
Explanation:
The correct option for the question about what occurs during the light-dependent reactions of plants is d. All the above. During these reactions, multiple processes take place:
Electron transport: Energy from sunlight captured by the chlorophyll in the photosystem II (PSII) reaction center is used to extract electrons from water. These electrons are then passed through a series of proteins in the thylakoid membrane known as the electron transport chain.The splitting of water: Water molecules are split to release electrons, protons (H+), and oxygen in a process called photolysis, which takes place in PSII.Hydrogen ion gradient establishment: The electron transport chain moves protons across the thylakoid membrane, creating a high concentration of protons (a low pH) inside the thylakoid lumen. This proton gradient is then used by ATP synthase to produce ATP in a process known as chemiosmosis.The initial source of electrons for the chloroplast electron transport chain is the splitting of water (photolysis), which occurs at PSII. The primary function of Photosystem II is to capture energy from sunlight to start these processes, while Photosystem I primarily works to produce NADPH.
Which of the following statements regarding the endomembrane system is false? Which of the following statements regarding the endomembrane system is false? The endomembrane system is involved in the synthesis, storage, and export of important molecules. The endomembrane system is a system of interrelated membranes that are all physically connected. The endomembrane system includes the rough and smooth endoplasmic reticulum. The endomembrane system includes the nuclear envelope.
The false statement about the endomembrane system is that all its components are physically connected. While they work closely together, they are not all physically continuous, though they form a functional network for modifying, packaging, and transporting cellular substances.
Explanation:The false statement regarding the endomembrane system is that it is a system of interrelated membranes that are all physically connected. In fact, the different components of the endomembrane system, such as the nuclear envelope, lysosomes, vesicles, the endoplasmic reticulum (both rough and smooth), and the Golgi apparatus, as well as the plasma membrane, are functionally connected though they are not all physically continuous with one another. Components like vesicles move between these structures, carrying substances within the cell, thus ensuring an interactive and dynamic system rather than a physically interconnected network.
The endomembrane system's main functions include the synthesis, storage, and export of important molecules. It also plays a crucial role in the production and modification of lipids and proteins which are necessary for building cellular membranes and for secretion out of the cell. It is important to note that the mitochondria and chloroplasts are not part of the endomembrane system despite being involved in various aspects of cell metabolism.
During sexual reproduction, novel mixtures of alleles are generated. Why is this?
a. in all diploid species, two alleles exist for every gene
b. a diploid individual has two different alleles for every gene
c. every gamete produced by a diploid individual has several different alleles of a single gene
d. during meiosis, the segregation of homologs is not random and different gametes end up with similar alleles of each gene
e. none of the above
Answer:
e. none of the above
Explanation:
Prophase-I of meiosis I include the pairing of homologous chromosomes followed by alignment of these pairs on the cell's equator in metaphase I.
During anaphase-I, the homologous chromosomes are separated from each other and begin to move towards opposite poles. Each homologous pair of chromosomes consists of one maternal and one paternal chromosome carrying corresponding alleles for the genes.
The separation of these homologous chromosomes during anaphase-I is random which means that each member of a homologous pair is randomly distributed to one of the poles. The independent separation of homologous chromosomes to the opposite poles results in unique allelic combinations in gametes.
How does eating influence high density lipoproteins (HDL) in the body?
Answer: The element with the greatest influence on cholesterol levels is the fat content of food. Not only the amount of cholesterol, but also the type of fat.
Explanation:
Cholesterol is a type of fat found in the body, which is used to make hormones and vitamin D. The liver makes cholesterol to handle these tasks, but cholesterol can also be incorporated into the body through foods such as meat, dairy, and poultry. If you consume a lot of these, the cholesterol levels could become too high.
There are two types of cholesterol:
High-density lipoprotein (HDL) or “good cholesterol”. It transports the excess of cholesterol to be expelled so it wont end up in the arteries. Low-density lipoprotein (LDL) or “bad cholesterol”. It transports cholesterol to the arteries, where it may collect in artery walls. This could lead to a buildup of plaque known as atherosclerosis which can increase the risk of blood clots and if one of them breaks away and blocks an artery, it could cause a stroke or heart attack.If there is a predominance of saturated fatty acids in the fat of the diet, a rise in serum cholesterol and LDL-cholesterol is caused. To lower the bad cholesterol, you should limit foods such as milk fats, fatty meats or sausage and include more fibre in your diet. On the other hand, polyunsaturated fatty acids - for example, those present in seed oils or fish - produce their reduction. Monounsaturated fatty acids, such as those provided by olive oil, act like polyunsaturated ones and, in addition, tend to raise HDL-cholesterol, so their use entails a greater benefit.