A series of programmed changes encoded in dna, through which a fertilized egg divides into many cells that ultimately are transformed into an adult organism, is known as <u>development.</u>
A fertilized egg first divides into a mass of cells called the morula. After about 5 days of fertilization, it forms a hollow ball of cells called the blastocyst. The cells in the outer layer of the blastocyst develops into the placenta and the inner mass of cells forms the tissues of the embryo. Cells of the inner most layer differentiate into the ectoderm forming the skin and the brain, mesoderm forming the muscles, bone, heart, kidney and the endoderm forming the gut lining, liver and the pancreas. This is called the complete development of the fertilized egg into the fetus.
All of the systems within the body interact with one another to keep an organism healthy. Although each system has specific functions, they are all interconnected and dependent on one another. The nervous system controls various organs of the body directly. The brain also receives information from many organs of the body and adjusts signals to these organs to maintain proper functioning.
Domain bacteria, Domain Archaea and Domain Eucarya
Answer:
- If it were true, all organisms would be complex and simple organisms would disappear
- It does not account for genetic mutations known to affect physical traits
Explanation:
Lamark's theory of evolution is that changes in the organism's physical form during its lifetime can be passed on to its offspring. In other words, he believed that children can inherit acquired characteristics from their parents.
The classic example is that he believed giraffes evolved long necks because they would stretch upwords to eat leaves from tall trees, elongating their necks, and then would pass on a longer neck to its children. Or in humans, that a body builder would make a muscular child because of their intense training!
There are a few problems with this theory:
- If we believe this theory, organisms would always be getting more and more complex and 'improved', so simple organisms would disappear.
- We know that changes to the DNA influence inherited physical characteristics, not simply continued use