Células falciformes: selección natural en humanos | Video HHMI BioInteractive

What is the primary cause of sickle cell anemia?

• A bacterial infection that attacks red blood cells.

• A mutation in a single gene that alters the hemoglobin protein.

• A dietary deficiency leading to abnormal blood cell production.

• An autoimmune response where the body attacks its own red blood cells.

How do the rigid, sickle-shaped red blood cells in sickle cell anemia lead to health problems?

• They increase the blood's oxygen-carrying capacity, leading to hyperoxia.

• They are more flexible and can squeeze through smaller blood vessels, improving circulation.

• They obstruct blood vessels, preventing proper blood flow and causing intense pain.

• They are quickly recognized and eliminated by the immune system, preventing disease.

What is the genetic condition of an individual who has sickle cell anemia?

• Homozygous with no sickle alleles

• Heterozygous with one sickle allele

• Homozygous with two sickle alleles

• Heterozygous with two normal alleles

Which statement accurately describes individuals with sickle cell trait?

• Their red blood cells are always sickle-shaped

• They have two copies of the sickle cell allele

• Their red blood cells only become sickle-shaped in low oxygen environments

• They always experience severe symptoms of sickle cell disease

In which regions of Kenya did Tony Allison observe a high frequency of the sickle cell trait?

• Only in the dry highlands around Nairobi

• In the lowlands near Lake Victoria and along the coast

• Throughout all regions of Kenya equally

• Only in areas with low mosquito populations

What advantage does having the sickle cell trait provide in regions where malaria is prevalent?

• It completely prevents individuals from contracting malaria

• It increases the number of malaria parasites in the blood

• It offers a higher probability of survival and reproduction

• It causes red blood cells to become more efficient at carrying oxygen

What is a known benefit of carrying the sickle cell trait?

• Increased oxygen-carrying capacity in blood.

• Enhanced resistance to bacterial infections.

• Protection against malaria.

• Improved athletic performance.

What pattern has been observed globally regarding the frequency of the sickle cell allele and malaria?

• The sickle cell allele is more common in regions with low historical malaria prevalence.

• There is no significant correlation between the sickle cell allele and malaria prevalence.

• The sickle cell allele is more frequent in areas with high historical malaria prevalence.

• The frequency of the sickle cell allele is decreasing worldwide due to modern medicine.

Besides the sickle cell trait, which of the following hereditary conditions affecting red blood cells can also make it difficult for the malaria parasite to infect or reproduce?

• Hemophilia, Cystic Fibrosis, Huntington's Disease.

• Ovalocytosis, Thalassemia, G6PD deficiency.

• Down Syndrome, Turner Syndrome, Klinefelter Syndrome.

• Type 1 Diabetes, Crohn's Disease, Multiple Sclerosis.

In evolutionary terms, why do specific gene mutations that affect red blood cells, like the sickle cell trait, become more prevalent in populations living in malaria-prone areas?

• These mutations are randomly selected for no particular reason.

• They provide a reproductive advantage by increasing resistance to malaria, leading to natural selection.

• They are a result of modern medical interventions in these regions.

• The mutations cause individuals to migrate away from malaria-prone areas.