The centrosome and centrioles are crucial for the process of cell division in animal cells. During cell division, two centrioles come together with some other special proteins and form the centrosome. As mitosis progresses and chromosomes line up at the equator of the cell, the centrosomes are responsible for what occurrence in the dividing cell? A) They help the cell's nucleus replicate DNA. B) They are responsible for pinching the single nucleus into two at the end of mitosis. C) They are responsible for the production of the proteins that reform the nuclear membrane. Eliminate D) They produce microtubules that attach themselves to the chromosomes and aid in separating them.

The presence of a mutant lac repressor that could not bind lactose would result in no transcription even when lactose was present because the mutant repressor would remain bound to the lac operator.

Further Explanation:

When lactose is unavailable, the repressor molecule binds to the DNA and prevents transcription of the genes. Therefore, the enzyme that is required for the lactose metabolism will not be produced. Comparatively, in the presence of lactose, the repressor molecule will bind to inducer (allolactose), which prevents binding of the repressor to DNA results in transcription of a gene. Enzymes accountable for the lactose metabolism will be produced. The mutated repressor molecule, which prevents binding to DNA, will result in the production of enzymes all the time, irrespective of the presence or absence of lactose. Genes responsible for the metabolism of lactose will be expressed all the time. If a mutation occurs in the repressor, it will prevent inducer binding. The repressor molecule will bind then to DNA permanently and blocks the activity of RNA polymerase. This results in no transcription and translation of operon. Presence of a mutated operator that does not allow the binding of a repressor would cause constitutive expression of the operon.

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Answer Details:

Grade: High School

Subjects: Biology

Chapter: Genetics

Keywords:

Lactose, metabolism, genes, produce, DNA, allolactose, repressor, transcription, repressor, operon, binding, enzyme, absence.

In a graph, the quadrants are marked from the top right corner and goes anti-clockwise

Hence we will have (+,+) in the Quadrant I

(- , +) in quadrant II

(-,-) in quadrant III

and

(+,-) in quadrant IV

Now the given point (-5,5) is a (-,+) and hence it lies in the quadrant II

Gradualism and punctuated equilibrium are two theories that explain how species might evolve over time. Gradualism suggests continuous slow change, while punctuated equilibrium points to long periods of stability followed by rapid changes. Both are vital in understanding the complexity of evolutionary processes in biology.

The term gradualism represents a predictive theory of how a species might change over time. This theory proposes that change occurs continuously and slowly over long periods. On the other hand, the term "assumes that nature can create whole new structures and organisms simply by environmental constraint" is likely referring to the concept of saltation or punctuated equilibrium, which suggests that species remain constant for long periods and that change, when it occurs, is rapid and significant. It's important to note that gradualism and punctuated equilibrium are two theories of evolutionary change that continue to be debated within the scientific community.

Contemporary biological anthropologists use an evolutionary perspective to understand the diversity of life through natural selection. These principles are instrumental in understanding why certain traits prevail over time. The ongoing evolution includes processes like mutation, natural selection, and speciation. The classical view of gradualism contends that species undergo continuous adaptation, but the punctuated equilibria view introduced by Stephen Jay Gould and Niles Eldredge provides an alternative model where species experience long periods of stability (equilibria) interrupted by brief periods of rapid evolution (punctuated).

Adaptationism allows us to understand how traits contributing to survival and reproduction become predominant within a population, which is a fundamental concept of natural selection. It is important to recognize that evolutionary theory isn't fixed, as it continues to develop with new technologies and cultural shifts, which might lead to a broader understanding of evolutionary forces beyond the classic model.

The icy waters of the Arctic and Antarctic Oceans sustenance a great amount of marine life. For millions of years, life has remained unchanged, making it possible for these animals to adapt themselves to these particular patterns of existence. Due to water's cohesiveness, water's polarity enticed to other water molecules. The hydrogen bonds in water grasp other water molecules unruffled. Also the Cohesion or known as water's attraction to other water molecules is one of the major properties of water. 

The correct answer is option (B) mitochondrion.

A Venn diagram represents an illustration of relationship between two groups, showing the characteristics of the groups separately in two circles and the similarities shown in the intersecting region of the two circles. When a Venn diagram is constructed to compare the organelles in plant and animal cells, the organelle that should be listed under "both" in the diagram is the mitochondrion.  Mitochondrion is a cell organelle that is the power house of the cell storing energy in the form of Adenosine triphosphate (ATP). It is present in both the plant and animal cells. It is made up of an outer membrane and an inner membrane with the inter membrane space, the cristae with the F1 particles and the mitochondrial matrix with proteins, enzymes, tRNA and the mitochondrial genome. Whereas centriole is present only in animal cell and chloroplast, cell wall are present only in plant cell.

Answer:

b

Explanation:

The answer is 700 milligrams needed toddlers should consume per day. Children need enough calcium to support their growing bones and teeth. Calcium is one of the body's most essential minerals and also has other necessary roles to play, including supporting a healthy nervous system and muscle function.

Final answer:

Removing leaves from a plant would cause it to starve due to the lack of photosynthesis. If roots are damaged or die, the plant cannot absorb water and minerals and will likely perish. Girdling interrupts the flow of nutrients, not water, but still leads to the eventual death of the plant.

Explanation:

Removing leaves from a plant would cause it to starve. Leaves are essential for photosynthesis, the process by which plants convert light energy into chemical energy in the form of glucose, which is a source of food for the plant. Without leaves, a plant cannot perform photosynthesis, leading to a lack of energy and eventual starvation.

If an herbicide causes roots to shrivel and die, the most direct consequence for the plant is that it would not be able to absorb water and minerals from the soil. Roots are vital for the uptake of these essential nutrients, and without functional roots, the plant would be unable to maintain necessary life processes and would likely die.

Effect of Girdling on Plants

Girdling a plant, which involves removing a band of bark from around the trunk, interrupts the downward flow of nutrients through the phloem but not the upward flow of water through the xylem. While the foliage does not initially wilt, the entire plant, including the roots, will eventually die because they cannot receive food manufactured by the leaves.

Answer: Low level of carbon dioxide, low temperature due to lack of sunlight will affect the process of photosynthesis.

Explanation:

The photosynthesis can be defined as the process by which autotrophs make their own food in the presence of sunlight with the help of carbon dioxide, water and other nutrients presents in soil.

If there will be inadequate amount of sunlight, or low level of carbon dioxide then the rate of photosynthesis will decrease.

Hydrolysis reactions in living things result in the formation of simpler molecules through the addition of water.

Hydrolysis reactions, in living things, result in the formation of simpler molecules through the addition of water. This process is important for breaking down complex molecules such as proteins, carbohydrates, and lipids into their individual building blocks. For example, a hydrolysis reaction involves the breaking of a peptide bond in a protein, resulting in the formation of amino acids.

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Answer:

A macrophage engulfs invading bacteria.

Explanation:

A nonspecific immune response is the body's first line of defense against invaders. It is a general immune response that requires no prior memory of the pathogen. A macrophage engulfing invading bacteria is an example of a nonspecific immune response.

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Answer:

Gonadotropins are polypeptide hormones and are secreted by the anterior pituitary gland.

Explanation:

Hypothalamus releases GnRH i.e gonadotropin releasing hormone which stimulates the anterior pituitary to secrete gonadotrophs such as FSH, ICSH and LH.

FSH (follicle stimulating hormone): In males it stimulates spermatogenesis. In females it stimulates growth of ovarian follicles.

ICSH (Interstitial cell stimulating hormone): In males, secretion of testosterone.

LH (Luteinising hormone): In femalestogether with FSH, it triggers ovulation, stimulates conversion of broken ovarian follicle into corpus luteum.

I believe the gonadotropins are hormones secreted by the gonads and are released by the testes and ovaries.

Gonadotropins are a group of hormones secreted by the female and male reproductive system. The organs that produce are Testes and Ovaries. The hormones are released due to action of another polypetide hormone called the gonadotropin releasing hormone that stimulates the male gonads (testis) to produce the steroid hormone called testosterone and the female gonads (ovaries) to produce estrogen.

All the gonadotropin hormones are steroid in nature and they are lipophilic hence they can pass through the lipid bilayer of the cell membrane and cause a change in the gene expression inside the nucleus of the target cell. Control of these hormones is via the Hypothalamus Pituitary Gonadal (HPG) axis and the Hypothalamus Pituitary Adrenal (HPA) axis. The steroid hormone testosterone can also be produced by the adrenal cortex of the adrenal gland in the topmost layer called the zona glomerulosa. The drugs clomid and ortho tri-cyclen target the these to axes in order to produce the desired response.

Clomid acts on the female HPG axis by acting on specific estrogen receptors in the hypothalamus where it has a negative feedback mechanism on the release of gonadotropin releasing hormone thus impacting the production of gonadotropic hormones through upregulation.

ortho tri-cyclen is an oral contraceptive that inhibits ovuating by acting on the female HPG axis where it has a negative feedback mechanism on the hormone Follicle Stimulating Hormone. It inhibits the FSH hormone production in the anterior pituitary gland meaning there will be no maturation of the ovarian follicle into the graafian follicle which will produce the hormone estrogen necessary for the thickening of the endometrial layer of the uterus. Inhibitin estrogen production also means that it will prevent the cervical mucus from becoming thin in order to allow the passage of sperms during sexual intercourse.

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Level: High School

Subject: Biology

Topic: Reproduction

Answer:

Skin is the largest organ of our body and it contains a lot of immune barriers that protects the pathogens form entering the skin. Majorly the nature of skin also helps in the external appearance of a person and also denotes age.

The skin protein such as keratin, melanin, elastin, and collagen are extracellular matrix proteins that plays a major role in maintaining the elasticity and texture of the skin. The dermal papillae is the region that  is present in the outer most layer of the skin that helps in the formation of hair follicles.

The illnesses of Anna Garcia had result in a breakdown of her body’s immune system that make her vulnerable to different infection. Her sickle cell disease and type 1 diabetes had made her weaker because the white blood cell that supposed to protect the body did not function properly and she often experienced fatigue and exhaustion because of low insulin. Due to these, she experienced urinary tract infection that made her more ill.