Question

In the course of evolution of the eukaryotic cell, the ability to store newly synthesized molecules is associated with: a) the nucleus of prokaryotes, b) vesicles that contain enzymes that perform dehydration synthesis, c) lysosomes, d) the nucleoid area of the cytoplasm. e) proteins produced outside of the Endoplasmic reticulum.  

Answer B why?

For eukaryote cells to evolve into new types of eukaryotic organism, which of the following would one expect to occur? a) All the cells are identical b) The endoplasmic reticulum is not involved. c) These specialized cells activate only the genes in their nucleoid area. d) Cells must be getting new genetic mutations and more DNA e) none of these are true.

answer D why?

In the evolution of the eukaryotic cell, these cells have key changes that include which of the following:

a) These cells reproduce by copying their DNA perfectly each generation.

b) They have their DNA in the nucleoid area.

c) have adapted the mesosome membrane system of the prokaryote to form a nucleus and an endoplasmic reticulum.

d) each new type of new eukaryote cell has its mRNA unchanged from its original mRNA,

e) none of these are true.

Most of the carbon dioxide we exhale is produced in:

A) glycolysis.

B) photosynthesis in the chloroplasts,

C) formation of pyruvate during glycolysis,

D) the mitochondrion during the Krebs cycle,

E) none of these.

Which is true of Prokaryote cells?

A) Their DNA exists in a nucleoid area the synthesis of proteins depends on random interactions between mRNA and rRNA,

B) They contain membrane-bounded compartments or organelles.

C) A true nucleus contains the DNA in the form of chromosomes

D) They all contain mitochondria

E) They contain many organelles in the cytoplasm

In both Prokaryotes and Eukaryotes, which of the following structures can cross cell membranes using the same protein channels as water?

A) mRNA,

B) triglycerides,

C) large, non-polar molecules,

D) DNA,

E) gases (CO₂ and O₂) and small ions.

plz explain the answer , Thank you

Answer 1

1.

Nutrients are the molecules that living organisms require for survival and growth but that animals and plants cannot synthesize themselves. Animals obtain nutrients by consuming food, while plants pull nutrients from soil. These nutrients are biological macromolecules that play a critical role in cell structure and function. Most biological macromolecules are polymers that are constructed by linking together many smaller molecules, called monomers.

Most macromolecules are made from single subunits, or building blocks, called monomers. The monomers combine with each other via covalent bonds to form larger molecules known as polymers. This occur with the release of water as bye product. This type of reaction is known as dehydration synthesis.

In dehydration synthesis reaction between two un-ionized monomers, such as monosaccharide sugars, the hydrogen of one monomer combines with the hydroxyl group of another monomer, releasing a molecule of water in the process. The removal of a hydrogen from one monomer and the removal of a hydroxyl group from the other monomer allows the monomers to share electrons and form a covalent bond. Thus, the monomers that are joined together are being dehydrated to aloow synthesis of a larger molecule.

As additional monomers join via multiple dehydration synthesis reactions, the chain of repeating monomers begins to form a polymer. Different types of monomers can combine in many configurations, giving rise to a diverse group of macromolecules. The major classes of biological macromolecules (complex carbohydrates, nucleic acids, and proteins), are composed of monomers that join together via dehydration synthesis reactions. Complex carbohydrates are formed from monosaccharides, nucleic acids are formed from mononucleotides, and proteins are formed from amino acids.

2.

A mutation is a change in DNA, the hereditary material of life. An organism's DNA infromation decides how it looks, how it behaves, and its physiology. So a change in an organism's DNA can cause changes in all aspects of its life and can result in formation of a new organism. Mutations are essential to evolution; they are the raw material of genetic variation. Without mutation, evolution could not occur.

The sequence of these bases in DNA encodes instructions. Some parts of the DNA are genes that carry the instructions for making proteins, which are long chains of amino acids. These proteins help build an organism. When a cell divides, it makes a copy of its DNA and sometimes the copy is not quite perfect. That small difference from the original DNA sequence is a mutation that occurs naturally. Mutations can also be caused by exposure to specific chemicals or radiation. These agents cause the DNA to break down and when the cell repairs the DNA, it might not do a perfect job of the repair. So the cell would end up with DNA slightly different than the original DNA and hence, a mutation. The only mutations that matter to large-scale evolution are those that can be passed on to offspring. These occur in reproductive cells like eggs and sperm and are called germ line mutations.

3.

option a is wrong as for evolution mutation and change in DNA occur through generations

option b is wrong as it is feature of prokariotes

option c is wrong because mesosomes   or chondrioids are folded invaginations in the plasma membrane of bacteria that are produced by the chemical fixation techniques used to prepare samples for electron microscopy. They were identified  as artifacts by the late 1970s and are no longer considered to be part of the normal structure of bacterial cells. These extensions are in the form of vesicles, tubules, and lamellae.

option d is wrong as number of bases removed from or inserted into a segment of DNA as a result of mutation is not a multiple of three. So the reading frame transcribed to the mRNA will be completely changed. Consequently, once it encounters the mutation, the ribosome will read the mRNA sequence differently, which can result in the production of an entirely different sequence of amino acids in the growing polypeptide chain.

4.

The carbon we breathe out as carbon dioxide comes from the carbon in the food we eat. The carbohydrates, fat and proteins we consume and digest are eventually converted to glucose. The glucose molecule is then combined with oxygen in the cells of the body in a chemical reaction called "cellular oxidation". This chemical reaction is exothermic, that is, it produces the chemical energy that is needed to drive all the other chemical reactions and functions of a cell. The end products of oxidation of glucose are carbon dioxide and water. It occurs in the mitochondria and through Krebs cycle.