Answer: B
Explanation: Transport of pebbles in a stream causes them to collide and rub against one another and the stream bed, and the resulting abrasion produces the familiar smooth and rounded shape of river rocks.
Water vapour and gases such as oxygen and carbon dioxide are able to move across the egg shell through small openings called pores. The egg contains all the nutrients that the developing chick needs during the three weeks of incubation period.
Explanation:
Free amino acid do not have a peptide bond , as the amino acid act as a monomer which multiplies and linked via peptide bond to generate protein chain .
A free amino acid have a carbonly group (- COOH ) and a -NH₂ group .
The formation of protein chain require at least two amino acids linked via peptide chain .
The role of peptide chain only comes in case of protein , because it acts as a linking species .
Hence , free amino acid does not have any peptide chain .
