Question:All known organisms use genetic information to produce protein molecules via the same genetic code. This finding strongly supports the hypothesis that __________.
a) the earliest macromolecules probably arose when lightning struck an oxygen-free atmosphere
b) all organisms are descended from one or a few common ancestors
c) the genetic code readily evolves by natural selection
d) there's only one possible way to encode information in a macromolecule
Answer:
b) all organisms are descended from one or a few common ancestors
Explanation:
Protein synthesis occurs when the nucleotide sequence of the mRNA is read in the form of genetic codes. A specific genetic code specifies the same amino acid in all living beings. For example, the code "UUU" codes for phenylalanine in all the living beings irrespective of their species. This suggests that all the life forms have originated from one or few common ancestors and the genetic code has been preserved during the course of evolution of various species.
photosynthesis produces oxygen and glucose as the end products whereby the glucose is used as food by plants and oxygen as a byproduct.
cellular respiration produces water and carbon dioxide and the end products and by products where by energy is stored
Vacuoles are essentially sacs surrounded by a membrane. They are used by cells as temporary storage sites. They often store food, enzymes, and other materials needed by the cell, and some vacuoles store waste products.
The correct answer is: a. n+1, n+1, n-1, n-1
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during mitosis or meiosis. There are three forms of nondisjunction:
1. failure of a pair of homologous chromosomes to separate in meiosis I ,
2. failure of sister chromatids to separate during meiosis II, and
3. failure of sister chromatids to separate during mitosis.
As a consequence of nondisjunction abnormal chromosome numbers appears. If nondisjunction occurs during the meiosis I (anaphase I), this means that at least one pair of homologous chromosomes did not separate. The consequence is two cells that have an extra copy of one chromosome and two cells that lack that chromosome.
