HISTORIA DE MÉXICO SIMULADOR PARA LA UNAM
Al periodo en el que Plutarco Elías Calles controló la política mexicana manipulando a los presidentes en turno, se le denominó
BIOLOGÍA SIMULADOR PARA LA UNAM
Para Darwin y Wallace el mecanismo evolutivo de mayor importancia es la
Ciencias Experimentales
Calcule la cantidad del reactivo limitante del cloruro de sodio en gramos que produce la reacción con 20 g de NaHCO3 de la siguiente ecuación:
NaHCO3 + HCl → NaCl + H2O + CO2
Considere las masas atómicas de Na = 23 g, Cl = 35.5 g, C = 12 g, O = 16 g y H = 1 g.
Literatura
Se caracteriza por ser un texto escrito con versos de arte mayor agrupados en dos cuartetos y dos tercetos con rima ABBA ABBA CDE CDE o ABBA ABBA CDC DCD.
Exani II, Exani II -> Comprensión Lectora
¿A cuál tipo de texto pertenece el fragmento?
Se denomina diurético (del lat. diuretĭcus, y éste del gr. διουρητικός / gr. δια- "a través de"; gr. ούρο- "orina"; sufijo gr. -ικός- "con relación") a toda sustancia que al ser ingerida provoca una eliminación de agua y electrolitos del organismo, a través de la orina y la expulsión de materia fecal.
LITERATURA SIMULADOR PARA LA UNAM
Es la clasificación de los textos de acuerdo a su estructura y composición
Inglés
Choose the correct answer for each question according to the information in the text. Each line is numbered to help you identify them quickly.
| Sunflowers Make Bees Poop—a Lot. Here's Why That's Good | |
|---|---|
| Paragraph | Text |
| [1] | Bumblebees and other pollinators face many threats, including pesticide exposure, |
| [2] | climate change, habitat loss due to agriculture and development, and pathogens |
| [3] | that ravage multiple species. But a recent finding may help lighten their load. |
| [4] | Previous studies have shown sunflower pollen can work like a medicine for |
| [5] | bumblebees afflicted by a parasite called Crithidia bombi, a single-celled organism |
| [6] | that takes up residence in the bee's gut [and harms their health]. But scientists couldn't |
| [7] | explain how sunflower pollen vanquished C. bombi—did it boost the bees' immune |
| [8] | function, or perhaps poison the parasite directly? |
| [9] | New research, published in the Journal of Insect Physiology, shows the answer is |
| [10] | deceptively simple. "Sunflower pollen makes bumblebees poo a whole lot," says lead |
| [11] | author Jonathan Giacomini, which flushes the parasite out. |
| [12] | Plant products like nectar and pollen are a treasure trove of potential insect medicines |
| [13] | that scientists are just beginning to understand, he adds. "There are natural things out |
| [14] | there that bees are interacting with that can be beneficial for them," Giacomini says. |
| [15] | And by making changes to the landscape, scientists hope we can help give bees a |
| [16] | fighting chance. |
| [17] | Plant power |
| [18] | If you happen upon a fuzzy, buzzing, flying creature in eastern North America, there's |
| [19] | a strong chance it's a common eastern bumblebee (Bombus impatiens). Yellow and |
| [20] | black striped with a rump covered in soft hairs, they're social insects that live in |
| [21] | colonies and love a good crevice—they build their homes in birdhouses, woodpiles, |
| [22] | abandoned burrows, and dense grasses. |
| [23] | [They] are important pollinators, both in the wild and in agriculture, where they're raised |
| [24] | and used to pollinate crops including tomatoes and pumpkins. Like other pollinators, |
| [25] | bumblebees face many threats, and C. bombi isn't even the biggest bumblebee |
| [26] | bugaboo. On its own, the parasite doesn't have much of an effect on a bumblebee's |
| [27] | health. But when food is scarce, C. bombi can shorten a bee's lifespan and even |
| [28] | reduce the number of young queens a colony can produce. |
| [29] | Lynn Adler is an evolutionary ecologist at the University of Massachusetts Amherst |
| [30] | who studies interactions between plants and insects. For years, she and longtime |
| [31] | collaborator Rebecca Irwin at North Carolina State University suspected pollinators |
| [32] | might be getting dosed by flowers since plants often invest chemically active |
| [33] | compounds into their nectar and pollen to help their genetic payload arrive at |
| [34] | its destination. |
| [35] | "Many plant defensive compounds can be medicinal at certain doses," Adler says. After |
| [36] | all, "most of our human medicines come from plants." |
| [37] | Giacomini discovered the effect of sunflower pollen as an undergraduate working in |
| [38] | Adler's lab in 2018. From [these] very first tests, sunflower pollen dramatically reduced |
| [39] | C. bombi parasite load in common eastern bumblebees, often clearing infection |
| [40] | completely. "We've been shocked at how consistent and effective sunflower pollen |
| [41] | has been," Adler says. |
| Elizabeth Anne Brown, National Geographic | |
Which of the following best describes the effect that sunflower pollen has on bumblebees?
FISICA SIMULADOR PARA LA UNAM
La relación entre el seno del ángulo incidente y el seno del ángulo de refracción es igual a un valor constante llamado índice de refracción, esto se conoce como:
Exani