The mechanisms of reproductive isolation prevent the reproduction of two individuals from different species. The prezygotic mechanisms disrupt the stages of reproduction before the forming of the zygote or prevent the mating at the start, and the postzygotic mechanisms affect the stages of reproduction after the forming of the zygote.
So, the first and the third example (the urchins and the grasshoppers) show the prezygotic mechanism, as the two individuals are not able to mate or form a zygote.
The second and the fourth example ( zonkey and the death of a zygote) show the working of the postzygotic mechanisms, as the zygote is formed, but it seems to be inviable, and the zonkeys are sterile, preventing the individual to reproduce.
Answer: option A - bottleneck effect
Explanation:
Whenever sudden change caused by human or natural disasters occurs in the environment leading to the reduction of organisms or biodiversity present to a lower size, such condition is referred to as BOTTLENECK EFFECT.
Answer:
The correct answer would be - 9 hours.
Explanation:
The half life of a drug is the time that is required to decrease or reduced to one half of the its original achieved level or the highest amount previously taken. The half life of drug is also known as the time a drug take to complete its action.
At a dose of 500 mg the Fluoxitine drug would be 250 mg in 3 hour as it is given that half life of this drug is 3 hours, 125 mg in 6 hours, and in the end 62.5 mg in 9 hours.
Thus, the correct answer is : 9 hours.
Answer:
C. Primary, secondary, and tertiary structures would be altered
Explanation:
Frameshift mutations refer to the mutations that change the reading frame of the gene. Frameshift mutations are mostly caused by insertion or deletion of nucleotide since addition or loss of nucleotide alters all the codons present downstream of the point of the mutation site. If frameshift mutation occurs at the beginning of the protein sequence, all the downstream amino acids would be altered.
The changed amino acid sequence would alter the primary structure of the protein. Since the secondary and tertiary structure of proteins is determined by interactions between the R groups of amino acids, their polarity, charge, etc., the altered amino acid sequence would also alter secondary, and tertiary of the protein.
