If adenine makes up 20% of the bases in a DNA double helix what percent of the b
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If adenine makes up 20% of the bases in a DNA double helix what percent of the bases are guanine? A) 40% B) 60% C) 80% D) 30% E) 20% RNA contains the nitrogenous base _ instead of _ which is only found in DNA A) cytosine guanine B) a deoxyribose sugar... a ribose sugar C) nucleotides ...nucleic acids D) uracil thymine E) adenine guanine After replication_ A) each new DNA double helix consists of two new strands B) each new DNA double helix consists of one old strand and one new strand C) each new DNA double helix consists of two old strands D) each new DNA double helix contains 25% of the old DNA double helix E) one new DNA double ix consists of two old strands and the other new DNA double helix consists of two new strands How many amino acids are common to all living systems? A) 10 B) 20 C) 30 D) 100 E) 1000 The shared genetic code of all life on Earth is evidence that_. A) bacterial cells arose earlier than eukaryotic cells B) the genetic code arose relatively late in the history of lied on Earth C) all life shares a common ancestry D) life was created by a deity E) DNA replication is error-free The expressed (coding) regions of eukaryotic genes are called_. A) introns B) caps C) D) promoters E) tails Translation converts the information stored in _ to _. A) protein DNA B) DNA RNA C) DNA a polypeptide D) RNA DNA E) RNA a polypeptide For the following questions, match the key event of meiosis with the stages listed below. I. Prophase II Metaphase I III. Anaphase I IV Telophase I V. Prophase II VI Metaphase II VII Anaphase II VIII Telophase II Tetrads of chromosomes are aligned at the equator of the spindles alignment determines independent assortment. A. I B) II C) IV D) VI E) VIIIExplanation / Answer
15)Chargaff's rules states that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases that is, the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.
According to Chargaff’s rule, A=T (Adenine , thymine ) and G=C(Gunanine,cytosine)
So if A is 20%, then T is also 20% and both G and C are 30% each .
Hence, the correct option is (D).
16) A total of five nitrogenous bases are used in the construction of nucleotides, which in turn build up the nucleic acids like DNA and RNA.
These nitrogenous bases are adenine (A), uracil (U), guanine (G), thymine (T), and cytosine (C). Pyrimidines include thymine, cytosine, and uracil.
Purines include adenine and guanine. DNA and RNA structures differ in their presence of nitrogenous bases.
Thymine is only found in DNA and Uracil is only found in RNA.
Hence, the correct option is (D).
17) Replication is the process of making identical copies of DNA before cell division. Replication depends on the pairing of bases between the two strands of DNA.The result of DNA replication is two DNA molecules consisting of one old and one new chain of nucleotides. Therefore, DNA replication is described as semi-conservative, as half of the chain is part of the original DNA molecule, and half is synthesised newly.
Hence, the correct option is (B).
18) About 20 aminoacids are common to all living systems. Out of which, 9 are essential to diet because human body cannot manufacture them.They are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Non essential aminoacids: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
Hence, the correct option is (B).
19) The genetic code is universal. Virtually, all species use the same genetic code for protein synthesis. Therefore, the genetic code of all sharedlife on earth is evidence that all life shares a common ancestry.
Hence, the correct option is (C).
20) The term ex-on signifies that they are expressed. Eukaryotic genes are composed of exons, which corresponds to protein-coding sequences.
Hence, the correct option is (C).
21) Translation requires the input of an mRNA template, ribosomes, tRNAs, and various enzymatic factors.
Translation of the mRNA template converts nucleotide-based genetic information into a protein product(polypeptide).
Hence, the correct option is (E).
Key events during each phase of meiosis:
Prophase1- Crossing over occurs
Metaphase 1- Homologous chromosomes move to equator of cells.
Anaphase 1- Homologous chromosomes separate and move to opposite poles of cell.
Telophase 1- Chromosomes meet at the poles of the cells and cytoplasm divides
Prophase 2- New spidle fibers form
Metaphase 2- Chromosomes meet at the equator
Anaphase 2- Centromere divides, sister chromatids move to opposite poles of cell.
Telophase 2- Nuclear membrane forms around each set of chromosomes, cytoplasm divides.
22) Tetrads of chromosomes are aligned at the equator of the spindle, alignment determines independent assorment II of chromosomes.
During metaphase 1 of meiosis, homologous pair of chromosomes orient randomly.Each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of other pairs. When chromosomes assort independently into gametes, the number of possible combinations are 2 power of n (2n) where n is the no of chromosomes.
Hence, the correct option is (B).
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