ATI TEAS Science Practice Test Preparation 2024

The correct answer is (B).

Carbon's atomic number is always 6, which means that carbon always has 6 protons. The most stable isotope of carbon is carbon-12, which has 6 neutrons and 6 protons.

Carbon-14, a radioactive isotope, has 8 neutrons; this can be deduced from the isotope's mass number (14), which is the number protons and neutrons.

The correct answer is (C).

Scurvy is the disease caused by vitamin C deficiency. Vitamin C is found in fresh fruit and vegetables. Therefore, scurvy used to be highly prevalent in sailors, whose diets lacked fresh produce. Vitamin C plays a key role in the formation of collagen, a protein found in connective tissue. A deficiency of vitamin C is characterized by lethargy, gum disease, edema, and more. This deficiency can be cured by consuming citrus fruits or other vitamin-C-rich foods.

Rickets is a disease caused by vitamin D deficiency. Vitamin D is synthesized in the human body upon exposure to sunlight. Therefore, Rickets was highly prevalent during the Industrial Revolution in Europe, where children worked in factories and were exposed to very little sunlight while growing up.

Beriberi is a disease caused by vitamin B1 deficiency. Since Vitamin B1 is abundant in whole rice, meat, and legumes, Beriberi is prevalent is certain areas in Asia where the diet is composed primarily of white rice.

Anemia is a disease caused by a red blood cell (RBC) deficiency or by a hemoglobin deficiency. Such deficiencies can be the result of malnutrition, infections, genetic diseases, and more.

The correct answer is (B).
In order to solve this, first find the redox state of each atom.  

• Start with the reactants: When an atom is uncharged and not in a molecule, its redox state is 0. When hydrogen is in a non-metal compound, its redox state is +1. When chlorine is in a compound (and not with oxygen or fluorine), its redox state is -1.  
• Moving on with the products: Chlorine is still in a compound, and not with oxygen or fluorine, its redox state is still -1.

Remember that the sum of the oxidation states of all the atoms or ions in a neutral compound is zero; therefore, since MgCl2 is not charged, the magnesium ion’s new redox state is +2. Lastly, the redox state of hydrogen as gas is 0.

To sum up the redox changes: Magnesium’s redox state increased from 0 to +2; therefore, it was oxidized. Hydrogen’s redox state dropped from +1 to 0; therefore, it was reduced. Note: Whenever an atom is oxidized, some other atom must be reduced, and vice versa. Since redox reaction involves the transfer of electron, for every acceptor there is a donor and vice versa. For this reason, distractors such as D can easily be eliminated.

The correct answer is (B).

The myelin sheath is a fatty layer that envelops the axons of many neurons in the nervous system. Its primary function is to insulate the axon and to increase the speed at which electrical impulses, or action potentials, are transmitted along the axon.

This is achieved through a process known as saltatory conduction, where the electrical impulses jump from one node of Ranvier (gaps in the myelin sheath) to the next, significantly speeding up signal transmission compared to unmyelinated fibers.

Efficient signal transmission is crucial for the rapid response of the nervous system to stimuli, coordination of movement, and processing of information. Options A, C, and D describe other aspects of neural function and protection that are not directly related to the role of the myelin sheath.

The correct answer is (B)

Ribosomes are small, complex molecular machines found within all living cells, and they play a critical role in the process of protein synthesis, also known as translation. In eukaryotic cells, ribosomes can be found both floating freely in the cytoplasm and attached to the endoplasmic reticulum, forming what is known as the rough ER due to its studded appearance under a microscope.

During protein synthesis, ribosomes facilitate the assembly of amino acids into protein chains according to the sequence of nucleotides in the messenger RNA (mRNA) molecule, which is a copy of the genetic instructions from DNA.

The ability of ribosomes to translate the genetic code into functional proteins is fundamental to all cellular processes, including growth, repair, and enzyme production. Options A, C, and D describe functions associated with other cellular organelles, such as the Golgi apparatus, mitochondria, and cell membrane, respectively.​