what is the main component that gives bones their rigidity and hardness

ATI TEAS 7

Mometrix TEAS 7 science practice test

1. What is the main component that gives bones their rigidity and hardness?

A. Collagen
B. Calcium phosphate
C. Cartilage
D. Ligaments

Correct answer: B

Rationale: Calcium phosphate is the main component that gives bones their rigidity and hardness. It combines with calcium hydroxide to form hydroxyapatite crystals, which provide strength and structure to bones. Collagen, on the other hand, provides flexibility and tensile strength. Cartilage is a type of connective tissue found in joints, and ligaments are fibrous tissues that connect bones to other bones, but they do not contribute to the rigidity and hardness of bones.

2. What potential consequences can chromosomal nondisjunction have on offspring?

A. Down syndrome, caused by an extra copy of chromosome 21.
B. Turner syndrome, characterized by the absence of one X chromosome in females.
C. Klinefelter syndrome, featuring one or more extra X chromosomes in males.
D. All of the above.

Correct answer: D

Rationale: - Chromosomal nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division, leading to an abnormal number of chromosomes in the resulting cells. - Down syndrome is caused by an extra copy of chromosome 21, resulting from nondisjunction during meiosis. Individuals with Down syndrome have three copies of chromosome 21 instead of the usual two. - Turner syndrome is characterized by the absence of one X chromosome in females, leading to a variety of physical and developmental features. - Klinefelter syndrome features one or more extra X chromosomes in males, typically resulting in infertility and other physical characteristics. Therefore, chromosomal nondisjunction can lead to various genetic disorders such as Down syndrome, Turner syndrome, and Klinefelter syndrome, making option D the correct answer.

3. Which part of the neuron receives signals from other neurons and conducts them toward the cell body?

A. Axon
B. Dendrite
C. Synapse
D. Myelin sheath

Correct answer: B

Rationale: The dendrites are the part of the neuron that receives signals from other neurons and conducts them toward the cell body. They play a crucial role in gathering incoming signals and transmitting them to the cell body for processing. The axon, on the other hand, is responsible for carrying signals away from the cell body. The synapse is the point of connection between two neurons facilitating communication, while the myelin sheath is a protective layer surrounding the axon that aids in accelerating signal transmission.

4. Adaptive radiation refers to the evolutionary process where:

A. A single ancestral species diversifies into multiple descendant species due to ecological pressures in a heterogeneous environment.
B. Two unrelated species evolve similar adaptations in response to similar environments, leading to convergent evolution.
C. A population becomes increasingly well-adapted to its current environment through continued natural selection.
D. The fossil record exhibits gaps or missing links in the evolutionary history of a lineage.

Correct answer: A

Rationale: - Adaptive radiation is a process where a single ancestral species diversifies into multiple descendant species to exploit different ecological niches within a heterogeneous environment. - This diversification occurs due to the different selective pressures present in various habitats, leading to the evolution of distinct traits and adaptations in different descendant species. - Option A accurately describes the process of adaptive radiation, where the initial species undergoes rapid speciation to occupy different ecological roles and adapt to diverse environmental conditions. - Options B, C, and D do not accurately describe adaptive radiation but refer to other evolutionary processes such as convergent evolution, natural selection, and gaps in the fossil record, respectively.

5. What is the muscular tube that connects the mouth to the stomach?

A. Pharynx
B. Esophagus
C. Trachea
D. Larynx

Correct answer: B

Rationale: The correct answer is B: Esophagus. The esophagus is indeed the muscular tube that connects the mouth to the stomach. Food is transported down the esophagus via peristalsis, a series of muscle contractions. The pharynx is the area behind the mouth and nasal cavity, the trachea connects the larynx to the bronchi in the lungs, and the larynx is the voice box located in the throat. Therefore, choices A, C, and D are incorrect in the context of the question.