Answer:
DNA can be described as the molecules which carries the genetic code for every individual. The DNA is made up of nucleotide bases which join the two strands of DNA. The sugar and phosphate form the backbone of the DNA.
Genes are the hereditary molecules which are made up of DNA. The alleles of a gene represent which traits will be carried by an organism.
Chromosomes are made up of genes. During reproduction, crossing over of DNA occurs and alleles of the genes assort independently due to which variations occur.
Answer:
A. The heartbeat can be heard
Explanation:
After the first trimester, during the fourth month, the heartbeat of the fetus becomes loud enough to be heard with the help of a stethoscope placed on the abdomen of the mother.
From fifth to the seventh month of the development, kicks and jabs are felt by the mother as the fetal legs grow and develops. Languo, a wrinkled pink colored skin covers the fetus.
Languo is in turn covered with a white greasy substance called vernix caseosa.
From eighth to ninth months, rotation of the fetus places its head pointing towards the cervix to facilitate childbirth later.
The development of testes takes place in the seventh month while the body hairs become disappeared in the eighth month.
<span>Earth went through a period of hot and also dry conditions and a wide spread drought.These conditions favored reptiles and therefore causing them to evolve during those conditions. Hope this helps :)</span>
