A light ray travels from air (refractive index 1.00) into water (refractive index 1.33). What happens to its speed and direction?

Correct Answer: C

Rationale: When a light ray travels from air (lower refractive index) to water (higher refractive index), its speed decreases due to the change in the medium. This is because light travels slower in denser mediums. As the light ray enters the denser medium, water in this case, it bends towards the normal (the line perpendicular to the surface of the water). This phenomenon is known as refraction. Choice A is incorrect as the speed of light decreases when entering a denser medium. Choice B is incorrect as the direction bends towards the normal, not away from it. Choice D is incorrect as the speed and direction of the light ray do change when moving from air to water.

Correct Answer: D

Rationale: Blood type O is considered the universal donor because individuals with type O blood can donate red blood cells to individuals with any ABO blood type (A, B, AB, or O) without causing an adverse reaction. Type O blood lacks A or B antigens on the surface of red blood cells, minimizing the risk of an immune response when transfused into individuals with different blood types. Therefore, type O blood is in high demand for blood transfusions in emergency situations when the recipient's blood type is unknown or when there is a shortage of specific blood types. Choices A, B, and AB are not considered universal donors. Individuals with blood types A, B, or AB can only donate to individuals with compatible blood types to avoid adverse reactions since they have A and/or B antigens on the surface of their red blood cells, making them incompatible with all blood types.

Correct Answer: C

Rationale: The purpose of genetic counseling is to provide information and support to individuals and families with genetic risks. Genetic counselors aim to explain the implications of genetic testing, discuss risks and options, and offer emotional and psychological support to help individuals make informed decisions regarding their genetic health. Choice A is incorrect because genetic counseling is not focused on treatment but rather on providing information and support. Choice B is incorrect as genetic counselors do not primarily diagnose genetic diseases in newborns but rather provide guidance and support based on existing diagnoses. Choice D is not the purpose of genetic counseling; genetic counselors do not collect DNA samples for research purposes but instead focus on assisting individuals and families in understanding and managing their genetic risks.

Correct Answer: A

Rationale: Rationale: - Homologous chromosomes are pairs of chromosomes that have the same genes in the same order, one from each parent. While they carry the same genes, they may have different alleles (variants of a gene). - Sister chromatids are exact copies of each other, formed during DNA replication. They are held together by a centromere and are produced during the S phase of the cell cycle. - During meiosis, homologous chromosomes pair up and exchange genetic material through crossing over, leading to genetic variation. Sister chromatids separate during mitosis to ensure each daughter cell receives an identical copy of the genetic material.

Correct Answer: C

Rationale: The epiglottis is a flap of cartilage located at the base of the tongue that covers the opening of the trachea during swallowing to prevent food and liquids from entering the airway. This action helps direct food and liquids into the esophagus, which leads to the stomach for digestion, while also protecting the respiratory system from potential blockages that could lead to choking or aspiration pneumonia. Options A, B, and D are incorrect as the epiglottis is not involved in storing bile, absorbing nutrients, or producing digestive enzymes. Understanding the role of the epiglottis in the swallowing process is crucial for maintaining proper respiratory and digestive functions.