When oxygen is absent, anaerobic respiration occurs ('an' means without).
Answer:
The correct answer is option 3. "Ab and aB".
Explanation:
Crossing over of two chromosomes, or chromosomal crossover, is the exchange of genetic material between two homologous chromosomes. This genetic process is responsible for the genetic variations that occurs during sexual reproduction. Usually crossing over occurrs between matching genetic sequences, therefore a diploid invidual with an AB allele that crosses over with an invidual with ab allele will exchange each allele in equal parts. The resulting chromosomes will be Ab and aB, one part per allele.
Four organic molecules make up all of the life on Earth. Organic molecules contain carbon and hydrogen chemically linked to one another in long chains, with carbon as the backbone and hydrogen atoms attached to the carbon atoms. These atoms' ability to attach to one another allows for the creation of innumerable compounds conducive to life. All organisms need four types of organic molecules: nucleic acids, proteins, carbohydrates and lipids; life cannot ex