Answer:
The answer is A) Homologous structures
Explanation:
Homologous Structures:
- Homologous structures are anatomical features in an organism that are structurally and functionally diverse but they originate from a single common ancestor.
- Homologous structures possess a similar basic internal structure but can have entirely different morphology and function.
- For example, the wings of a bat and a human's arm have the same internal structure but they have different functions.
- Vestigial structures are evolutionary remnants that no longer serve a purpose in modern forms or descendants of the original organism.
- Inherited and developmental are out of context in terms of evolutionary relationships.
The <span> Nitrogenous bases </span><span> of dna form the rungs, linking the Nucleotides strands together through P</span>hosphodiester bonds . Each rung<span> is made up of two bases that </span>link together and because of their chemical nature, A (<span>adenine ) </span><span>will only </span>link with T (thymine) and G (<span>guanine ) </span><span> will only </span>link with C (<span>cytosine)</span><span>. </span>Nucleotides are joined together<span> to </span>form<span> two long </span>strands <span>that spiral to build a structure called a double helix. If it looks like a ladder, the phosphate and sugar molecules would be the </span>sides<span>, while the bases would be the </span>rungs.
Virulence factors of virus aids in its ability to infect cells.
Explanation:
Virulence factors help pathogenic microbes to infect host cells by virulence mechanisms – invade host, cause and spread disease, evade the defense or immune mechanism of the host. These factors makes the virus to grow, replicate, and modify the host cells due to its toxicity.
Viruses binds to the receptor protein of the host cell.
Different types of virulent factors are: invasion factors, adhesive or adherent factors, capsules, endo and exotoxins, etc.
The virulence factors decides the severity and rate of spread of an infection
<h2>b) option is correct </h2>
Explanation:
- Some bacterial toxins cause disease by altering the activity of G protein, cholera toxin is one of them
- Cholera toxin catalyse ADP ribosylation of Gs and blocks GTPase activity thus Gs GTP become permanently active
- Constitutive activation of Gs protein continuously induce adenylyl cyclase, cytosolic cAMP level rises that leads to activation of protein kinase A (pKA)
- Activated pKA catalyse phosphorylation of two transmembrane proteins of intestinal epithelial cells:
- CFTR cause excessive outflow of Cl- ion and Na+ H+ exchange cause efflux of Na+ ion, both enters in gut and form Na+ Cl-
- Na+Cl- leads to outflow of water from the gut, resulting in diarrhea and dehydration and this condition may cause death of organisms due to loss of water and ions
Answer:
Gaseous waste through stomata and lenticels.
Stored solid and liquid waste by shedding leaves, peeling of bark and falling of fruits.
By secreting waste in the form of gum and resins.
Excrete waste into the soil around them.
