KMU-CAT TEST 2

Question number 1

Which of the following correctly describes the stages of HIV infection? •

Explanation:
Correct Option: C Explanation: Dear GrammLogians! HIV has 3 stages: acute infection, clinical latency, and AIDS. Full recovery does not naturally occur

Question number 2

What is not directly controlled by the nervous system?

Explanation:

Question number 3

Viruses are unique because they contain either DNA or RNA but never both. Which statement is true? •

Explanation:
Correct Option: C Explanation: Dear GrammLogians! Smallpox (variola virus) is a double-stranded DNA virus.

Question number 4

A farmer uses sperm from a black male sheep to artificially inseminate (fertilise) 20 light brown female sheep. All of the offspring produced were black. Which statement explains these results? •

Explanation:
Correct Option: D Explanation: Dear GrammLogians! Since all offspring are black, the black allele must be dominant. For all offspring to express the dominant trait and show no variation, the male must be homozygous dominant (BB).

Question number 5

A patient has her gall bladder surgically removed. How will this affect the functioning of her body? •

Explanation:
Correct Option: B Explanation: Dear GrammLogians! The gall bladder stores and concentrates bile, which is essential for the emulsification and digestion of fats. Its removal impairs efficient fat digestion.

Question number 6

Which of the following is an advantage of mRNA vaccines compared to traditional vaccines?

Explanation:
Correct Option: B Explanation: GrammLogians mRNA vaccines can be quickly developed in a laboratory from a genetic sequence and mass-produced without the need to grow live pathogens, which is a slower process for traditional vaccines.

Question number 7

Which statement about dominant and recessive alleles is not correct? •

Explanation:
Correct Option: D Explanation: GrammLogians Dominance is not about physical strength; it is a genetic relationship where the dominant allele masks the expression of the recessive allele in a heterozygote.

Question number 8

Which sign of syphilis may appear many years after infection, if treatment is not given?

Explanation:
Correct Option: C Explanation: GrammLogians Tertiary (late-stage) syphilis can occur 10-30 years after initial infection and can cause severe damage to the brain, nerves, eyes, heart, and other organs

Question number 9

What is a result of natural selection? •

Explanation:
Correct Option: C Explanation: GrammLogians Natural selection is the process where organisms with traits that increase survival and reproduction in a specific environment become more common. Insecticide resistance is a classic example of this evolutionary process.

Question number 10

Which process does not depend on respiration? •

Explanation:
Correct Option: A Explanation: GrammLogians Diffusion is a passive process that moves substances down a concentration gradient and does not require energy (ATP) from respiration. The other processes all require cellular energy.

Question number 11

Which fact about proteins makes them essential components of the human diet:

Explanation:
Correct Option: D Explanation: Dear GrammLogians! While proteins can be used for energy and hormone synthesis, their essential role in the diet is to supply essential amino acids. These are the building blocks for protein synthesis that the body cannot produce on its own and are vital for growth, repair, and maintaining cellular structures.

Question number 12

Which combination of mineral and vitamin is required for strong bones?

Explanation:
Correct Option: B Explanation: Dear GrammLogians! Calcium is the primary mineral that provides the structural hardness of bones and teeth. Vitamin D is crucial because it regulates the absorption of calcium from the diet in the intestines; without sufficient Vitamin D, the body cannot absorb calcium effectively, regardless of how much is consumed.

Question number 13

Chemicals in tobacco smoke lead to the breakdown of the elastic tissue in the walls of the alveoli. What is the name of this condition?

Explanation:
Correct Option: D Explanation: Dear GrammLogians! Emphysema is a chronic lung condition characterized by the destruction of the alveolar walls and the loss of their elastic recoil. This damage traps air in the lungs, reduces the surface area available for gas exchange, and causes severe shortness of breath. It is directly linked to the long-term inhalation of irritants like tobacco smoke.

Question number 14

Which part of the brain controls body temperature?

Explanation:
Correct Option: A Explanation: Dear GrammLogians! The hypothalamus acts as the body's thermostat and is the primary center for maintaining homeostasis. It contains specialized neurons that detect changes in blood temperature and initiates responses like sweating or shivering to regulate and stabilize the body's core temperature.

Question number 15

Which structure in the brain registers changes in the blood concentration?

Explanation:
Correct Option: B Explanation: Dear GrammLogians! The hypothalamus is equipped with osmoreceptors that are highly sensitive to changes in the solute concentration (osmolality) of the blood. When it detects high blood concentration, it triggers the release of antidiuretic hormone (ADH) from the pituitary gland to conserve water and stimulate thirst.

Question number 16

What are the responses to decreased body temperature?

Explanation:
---Correct Option: C Explanation: Dear GrammLogians! In response to cold, the body employs two key mechanisms to generate and conserve heat. Shivering is rapid muscle contraction that produces thermal energy. Vasoconstriction is the narrowing of blood vessels near the skin's surface to reduce blood flow and minimize heat loss to the external environment

Question number 17

Which blood vessel contains a high oxygen concentration, low carbon dioxide concentration and a high pressure?

Explanation:
Correct Option: A Explanation: Dear GrammLogians! The aorta is the main and largest artery that receives oxygenated blood directly from the left ventricle of the heart. The powerful ventricular contraction pumps blood into the aorta at high pressure. This blood is rich in oxygen and has a low concentration of carbon dioxide as it is being delivered to the body's tissues.

Question number 18

In ventricular contraction of the right ventricle, which of the following valves is closed? •

Explanation:
Correct Option: B Explanation: Dear GrammLogians! During the contraction phase (systole) of the right ventricle, the tricuspid valve, which separates the right atrium from the right ventricle, closes tightly. This prevents the backflow of deoxygenated blood into the right atrium, ensuring it is forced forward through the open pulmonary valve into the pulmonary artery.

Question number 19

Which blood vessel will have the highest urea concentration after a protein-rich meal?

Explanation:
Correct Option: B Explanation: Dear GrammLogians! After a protein-rich meal, amino acids are absorbed into the bloodstream and transported directly to the liver via the hepatic portal vein. The liver is the primary site for deamination, the process where excess amino acids are broken down, producing urea as a waste product. This newly synthesized urea is then released into the blood draining from the liver, which is carried away by the hepatic vein, making it the vessel with the highest urea concentration at that point.

Question number 20

When the water concentration in blood falls, there is less water concentration in urine which makes the water concentration in blood rise, leading to more water concentration in urine. Why is this a negative feedback system?

Explanation:
Correct Option: D Explanation: Dear GrammLogians! A negative feedback system works to maintain stability by counteracting changes. In this scenario, a fall in blood water concentration (the change) triggers a response—producing more concentrated urine to conserve water. This action returns the blood water concentration back to its normal level, effectively reversing the initial change and restoring homeostasis.

Question number 21

In a kidney dialysis machine, which substance cannot diffuse through the dialysis membrane? •

Explanation:
Correct Option: B Explanation: Dear GrammLogians! The dialysis membrane acts as a semi-permeable barrier with small pores that allow small molecules like waste products (urea), ions (sodium), and glucose to pass through. Insulin, however, is a relatively large protein hormone. Its molecular size is too large to fit through the pores of a standard dialysis membrane, so it is retained in the patient's blood.

Question number 22

What is the role of motor neurons in reflex action?

Explanation:
Correct Option: A Explanation: Dear GrammLogians! Motor neurons are responsible for transmitting the response signal from the central nervous system (CNS) to an effector, such as a muscle or gland, which then carries out the reflex action.

Question number 23

A non-competitive inhibitor decreases the rate of an enzyme-catalyzed reaction by: •

Explanation:
Correct Option: C Explanation: Dear GrammLogians! A non-competitive inhibitor binds to an allosteric site on the enzyme, which is a location other than the active site. This binding changes the three-dimensional shape of the enzyme, often distorting the active site and preventing the substrate from binding effectively, thereby reducing the reaction rate.

Question number 24

The backbone of a DNA molecule is composed of:

Explanation:
Correct Option: C Explanation: Dear GrammLogians! The structural backbone of a DNA strand consists of alternating sugar (deoxyribose) and phosphate groups. These are linked by strong phosphodiester bonds, forming the sides of the DNA "ladder," while the nitrogenous bases form the "rungs."

Question number 25

Before entering the Krebs cycle, fatty acids are converted into:

Explanation:
Correct Option: A Explanation: Dear GrammLogians! Fatty acids undergo a metabolic process called beta-oxidation. In this process, the long carbon chains of fatty acids are broken down into multiple two-carbon units, which are then bonded to coenzyme A to form Acetyl-CoA molecules. This Acetyl-CoA is the central molecule that enters the Krebs cycle to produce energy.

Question number 26

Which of the following did Darwin propose as the mechanism for evolution? •

Explanation:
Correct Option: B Explanation: Dear GrammLogians! Charles Darwin's foundational contribution to evolutionary theory was the proposal of natural selection as its primary mechanism. This process describes how individuals with heritable traits that are advantageous for their environment are more likely to survive, reproduce, and pass those traits on to the next generation, leading to evolutionary change over time.

Question number 27

The human skull is composed of multiple bones joined by immovable joints called sutures. Which of the following bones primarily contributes to both the cranial floor and the lateral walls of the cranium?

Explanation:
Correct Option: C Explanation: Dear GrammLogians! The sphenoid bone is a complex, bat-shaped bone that is a keystone of the cranial base. It articulates with all other cranial bones and forms a significant part of both the floor of the neurocranium and the lateral walls of the skull, contributing to the structure of the orbits (eye sockets) as well.

Question number 28

In the human vertebral column, which region has vertebrae with facets that articulate with ribs?

Explanation:
Correct Option: A Explanation: Dear GrammLogians! The twelve thoracic vertebrae are uniquely characterized by the presence of costal facets on their bodies and transverse processes. These smooth, articular surfaces form joints with the heads and tubercles of the ribs, respectively, creating the structural framework of the thoracic cage that protects the heart and lungs

Question number 29

If a nerve impulse is stimulated to contract the bicep muscle, what will be the effect?

Explanation:
Correct Option: A Explanation: Dear GrammLogians! The biceps brachii is a major flexor muscle of the arm. When its muscle fibers receive a nerve impulse and contract, they shorten, pulling on the radius bone of the forearm. This action causes flexion at the elbow joint, which bends the arm.

Question number 30

A female carrier of hemophilia marries a normal male. What is the probability that a son will be hemophilic?

Explanation:
Correct Option: C Explanation: Dear GrammLogians! Hemophilia is an X-linked recessive disorder. A female carrier has the genotype X^H X^h (one normal X, one affected X). A normal male is X^H Y. Their sons will inherit either the mother's X^H (normal) or X^h (hemophilic) chromosome and the father's Y chromosome. Therefore, there is a 50% chance a son will inherit the affected X chromosome and have hemophilia.

Question number 31

Why are females less frequently affected by hemophilia?

Explanation:
Correct Option: C Explanation: Dear GrammLogians! Hemophilia is an X-linked recessive disorder. Females (XX) need two copies of the defective allele (one on each X chromosome) to be affected. Males (XY) only need one copy on their single X chromosome. This makes the condition much more common in males, as females are typically carriers if they have only one copy.

Question number 32

Which process is used to produce insulin commercially? •

Explanation:
Correct Option: D Explanation: Dear GrammLogians! Commercial insulin is produced using recombinant DNA technology. The human gene for insulin is inserted into a bacterium, such as E. coli. The genetically modified bacteria then act as living factories, producing large quantities of human insulin that can be harvested and purified for medical use.

Question number 33

Which of the following diseases is caused by a DNA virus?

Explanation:
Correct Option: B Explanation: Dear GrammLogians! Hepatitis B is caused by the Hepatitis B virus (HBV), which is a double-stranded DNA virus. In contrast, the other diseases listed are caused by RNA viruses: Influenza (RNA), Measles (RNA), and COVID-19 (SARS-CoV-2, RNA).

Question number 34

The causative agent of AIDS is a virus that primarily infects:

Explanation:
Correct Option: C Explanation: Dear GrammLogians! The Human Immunodeficiency Virus (HIV), which causes AIDS, specifically targets and infects helper T-lymphocytes (CD4+ cells). These cells are crucial for coordinating the immune response. Their destruction severely weakens the immune system, leading to AIDS.

Question number 35

Which of the following is an example of naturally acquired active immunity? •

Explanation:
Correct Option: D Explanation: Dear GrammLogians! Naturally acquired active immunity occurs when a person's own immune system produces antibodies in response to fighting off a natural infection. This provides long-lasting protection. Vaccination is artificial active immunity, while breastfeeding and antibody injections are forms of passive immunity.

Question number 36

Which type of immune cell is primarily responsible for antibody formation? •

Explanation:
Correct Option: D Explanation: Dear GrammLogians! B-lymphocytes (B cells) are the white blood cells responsible for the humoral immune response. When activated by an antigen, they differentiate into plasma cells, which are factories that produce and secrete large quantities of antibodies specific to that antigen.

Question number 37

Where does the placenta allow exchange of materials to take place between mother and fetus? •

Explanation:
Correct Option: B Explanation: Dear GrammLogians! The placenta is a temporary organ that implants and develops in the wall of the uterus. It is at this interface between the uterine wall and the fetal chorionic villi that the crucial exchange of oxygen, nutrients, and waste products occurs between the maternal and fetal bloodstreams.