Answer:
There is a higher oxygen content in the air of the lungs than that of oxygen-depleted blood and a lower carbon dioxide concentration. This gradient of concentration causes gas exchange during respiration.
Explanation:
The correct answer is option A- HIV virus.
HIV virus is an example of enveloped virus, that has the ability to infect a host cell by attaching itself to it and fusing with the host cell. Once infected, the virus leaves the host cell and moves to another cells to infect them. The HIV virus contains glycoprotein spikes to attach to the host cell.
The term ‘Crossing over’ was used by Morgan and Cattell. It is a process in which there is exchange of chromosome segments between non-sister chromatids of a homologous chromosomes. It occurs during pachytene stage of prophase I of meiosis cell division.
Significance of crossing over:
- Crossing over provides genetic variation in all sexually reproducing organisms.
- It creates new combination of genes or genetic recombination and produces hybrids.
Per calendar year (365 days) there are 31536000 seconds
Chloroplasts are the organelles that contain the chlorophyll pigment, which is essential for the good-making process of photosynthesis.
