Answer:
The circulatory and respiratory systems interact to transport carbon dioxide to the lungs, where it is expelled from the body.
Explanation:
Carbon dioxide produced by the cells and tissues during cellular respiration is removed from the body through the interaction of the circulatory and respiratory system. The medium of transport of carbon dioxide is the blood which carries to the lungs, where it is expelled from the body in ordernto maintain homeostasis in the body.
Carbon dioxide molecules are transported in the blood from body tissues to the lungs in three ways:
1. Dissolution directly into the blood - due to its greater solubility in blood than oxygen, carbon dioxide is dissolved in blood plasma. On reaching the lungs, it leaves the blood by diffusion and is then expelled out of the body.
2. Binding to hemoglobin - carbon dioxide binds reversibly with haemoglobin in the red blood cells to form a molecule called carbaminohemoglobin. When it reaches the lungs, the carbon dioxide freely dissociate from the hemoglobin and is expelled from the body.
3. Carried as a bicarbonate ion - the majority of carbon dioxide molecules are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the red blood cells. The enzyme carbonic anhydrase within the red blood cells quickly converts the carbon dioxide into carbonic acid (H2CO3) which then dissociates into bicarbonate and hydrogen ions. The bicarbonate ions leaves the red blood cells in exchange for chloride ions in the plasma. The bicarbonate ions then travel in plasma to the lungs, where they enter the red blood cells again. It combines with hydrogen ions from the haemoglobin to form carbonic acid. Carbonic anhydrase breaks carbonic acid down into water and carbon dioxide which is then expelled from the lungs.
Answer:
B) Nitrogen-fixing bacteria and lightning
Explanation:
Nitrogen cycle is the natural process in which atmospheric nitrogen is converted into nitrite and nitrate with the help of bacteria.
Nitrogen cycle is directly dependent on nitrogen-fixing bacteria and lightning.
As bacteria are responsible for most of the chemical conversion in the nitrogen cycle such as nitrogen fixation (first step) is done by soil bacteria (Cyanobacteria) that form ammonia, which is toxic to plants; nitrification in which ammonia is converted into nitrites and nitrates with the help of Nitrobacter and denitrification bacteria involve Pseudomonas, and Achromobacter which convert nitrite and nitrate into nitrogen.
The lightning breaks nitrogen molecules and allow it to combine with oxygen in atmosphere which further dissolve in rain and form nitrates.
Hence, the nitrogen cycle is most directly dependent upon nitrogen-fixing bacteria and lightning and the correct option is B.
Answer:
reverse transcriptase (RT) is an enzymeused to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by retroviruses to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes, and by some non-retroviruses such as the hepatitis B virus, a member of the Hepadnaviridae.
Explanation:
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Natural selection and speciation: 'Ecological speciation'. ... Natural selection is generally recognized as a central mechanism of evolutionary change within species. Thus, natural selection plays a major role in generating the array of phenotypic and genetic diversity observed in nature.
