Question 1

Which of the following best describes the sliding filament mechanism in skeletal muscle contraction?

Accepted Answer

Myosin heads bind to actin filaments and pull them toward the center of the sarcomere, shortening the muscle.

Question 2

A patient is unable to perform isotonic contractions but can still generate muscle tension. Which of the following best explains this scenario?

Accepted Answer

The patient's muscles can generate force without changing length, indicating isometric contractions are intact.

Question 3

Which structure is responsible for releasing calcium ions during muscle contraction, and what is the significance of this release?

Accepted Answer

The sarcoplasmic reticulum releases $$\mathrm{Ca$$^{2+}$$}$$, which binds to troponin, allowing myosin to bind to actin.

Question 4

During inhalation, which of the following best describes the change in pressure inside the lungs and the resulting airflow?

Accepted Answer

The pressure inside the lungs decreases below atmospheric pressure, causing air to flow into the lungs.

Question 5

Which muscle group is primarily responsible for increasing the volume of the thoracic cavity during inspiration?

Accepted Answer

The diaphragm and external intercostal muscles contract, increasing thoracic volume.

Question 6

A person with a mutation in the gene encoding for the enzyme lactase is unable to digest lactose. Which digestive structure is primarily affected by this deficiency?

Accepted Answer

The small intestine, where lactase is produced and lactose is digested.

Question 7

Which of the following best explains why the small intestine has a large surface area?

Accepted Answer

To maximize nutrient absorption by increasing contact between digested food and absorptive cells.

Question 8

Which of the following best describes the difference between basal metabolic rate (BMR) and standard metabolic rate (SMR)?

Accepted Answer

BMR is measured under standardized resting conditions in endotherms, while SMR is measured in ectotherms at a specific temperature.

Question 9

A child inherits one allele for brown eyes (B) and one for blue eyes (b). If brown is dominant, what is the child's genotype and phenotype?

Accepted Answer

Genotype: $$Bb$$; Phenotype: Brown eyes

Question 10

Which of the following best describes the Law of Independent Assortment?

Accepted Answer

Alleles of different genes assort independently of one another during gamete formation.

Question 11

A woman who is a carrier for a sex-linked recessive disorder (X-linked) has children with a man who does not have the disorder. What is the probability that their son will have the disorder?

Accepted Answer

$$50\%$$

Question 12

Which of the following scenarios best illustrates incomplete dominance?

Accepted Answer

A cross between red-flowered and white-flowered plants produces offspring with pink flowers.

Question 13

Which of the following best explains why some recessive genetic disorders remain prevalent in human populations?

Accepted Answer

Carriers (heterozygotes) do not express the disorder and can pass the allele to offspring.

Question 14

Which of the following best describes the function of peristalsis in the digestive system?

Accepted Answer

Coordinated contractions of smooth muscle propel food through the digestive tract.

Question 15

A karyotype reveals an individual with 47 chromosomes, including three copies of chromosome 21. What is this condition called, and what is the underlying cause?

Accepted Answer

Down syndrome; caused by nondisjunction during meiosis.

Question 16

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the phenotype of a heterozygote.

Question 17

Which of the following best explains how linked genes can be separated during meiosis?

Accepted Answer

Crossing over during prophase I can exchange segments between homologous chromosomes, creating new allele combinations.

Question 18

Which of the following is a real-life example of polygenic inheritance?

Accepted Answer

Human skin color, which is influenced by multiple genes.

Question 19

Which of the following best describes the role of the diaphragm in respiration?

Accepted Answer

Contraction of the diaphragm increases thoracic volume, decreasing lung pressure and drawing air in.

Question 20

Which of the following best explains how environmental factors can influence phenotypic expression of a genotype?

Accepted Answer

Environmental factors such as nutrition or temperature can affect how genes are expressed, altering the phenotype.

Human Biology Exam 2 Study Guide: Muscular, Respiratory, Digestive Systems & Genetics

Study Guide - Practice Questions

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