Answer:
B (Metaphase I)
Explanation:
Meiosis is one of the two types of cell divisions that results in 4 daughter cells (gametes) with each having half the number of chromosomes as the parent cell. During meiosis, cell division occurs twice because before the separation of two halves of a duplicated chromosome called sister chromatids, there still need to be separation of homologous pairs, which is a similar but non-identical pair of chromosome received from both parents. Hence, meiosis occurs in a two step division process; meiosis I and meiosis II.
During Prophase I, which is the first stage of meiosis I, homologous chromosomes pair up side by side to form a structure called TETRAD or BIVALENT and likely undergo crossing over( when segments of homologous chromosomes get broken and refixed interchangeably).
After crossing over, the spindle fibres (from the centrosomes) begin to attach to the centromeres of each chromosomes and move them towards the center of the cell called METAPHASE PLATE. Hence, they become aligned on the equator towards either side of the pole. Each chromosome attaches to microtubules from one pole of the spindle and the two homologues of a pair bind to microtubules from opposite poles. Hence, in Metaphase I, homologous pairs, not individual chromosomes, line up at the Metaphase plate/equator for separation.
The orientation of the line up of homologous chromosomes determines which chromosomes enter into the same cell i.e. the alignment of chromosomes towards the same pole determines which chromosomes enter into the same cell to form the genetic composition of gametes. In an organism with two sets of chromosomes (diploid), there are four possible combinations in which chromosomes are arranged in the metaphase plate, resulting in differences in chromosomal distribution in daughter cells/gametes, the process of independent assortment
Answer:
The number of moths in 5th generation (G5) with:
Typica phenotype (white) = 878
Carbonaria phenotype (black) = 54
total moths observed = 932
5th generation Phenotype frequency:
f (Typica) = Number of Typica phenotype in G5/ total moths in 5th gen
f (Typica) = 878/ 932
= 0.94
f (Carbonaria) = Number Carbonaria phenotype in G5/ total moths in 5th gen
f (black) = 54/ 932
= 0.057
The hormones send signal to the mammary glands in the body for it to start to produce milk to feed the baby. However there are times humans rely on to cow's milk. There are differences though between the two.Human milk has more whey protein compared to the cow yet they has less casein which is another type of protein compared to cow's milk. For carbohydrates, human milk is higher than the cow's milk. For the fatty acid, the cow's milk contains more unsaturated fat.
Answer:
La segunda exposición desencadena la fase de 'respuesta' asociada a la reacción alérgica
Explanation:
La alergia se puede considerar como una respuesta desmedida del sistema inmune cuando un individuo entra en contacto con ciertas sustancias que son inocuas para la mayoría de la población, pero que en personas alérgicas desencadenan fuertes reacciones de hipersensibilidad. La alergia tiene dos fases conocidas como fase de sensibilización y fase de respuesta. La primera fase de sensibilización es donde el individuo entra en contacto con los 'antígenos' del alérgeno, lo cual provoca que el individuo genere anticuerpos IgE los cuales combaten al alérgeno (el sistema inmune considera que esta sustancia es potencialmente dañina), mediante la generación de anticuerpos de IgE que se unen a receptores de células del sistema inmune (eosinófilos, basófilos y mastocitos). La segunda fase de respuesta se produce cuando el individuo entra de nuevo en contacto con el alérgeno. Durante el segundo contacto, los antígenos del alérgeno interactúan con anticuerpos específicos de IgE que se encuentran sobre la superficie de células del sistema inmune, desencadenando la degranulación de estas células (mastocitos) y la consecuente liberación de mediadores químicos de la alergia tales como, por ejemplo, histamina, los cuales son responsable de los síntomas típicos de la alergia (tos, estornudos, picor, enrojecimiento de ojos, urticaria, inflamación, etc.).
Label A - G1 phase ; the cell experiences rapid growth and metabolic activity
Label B- S phase - DNA synthesis and replication takes place,
Label C- G2 phase- the cell is preparing for division.
Label D - mitosis- which involves cell and cytoplasmic division
Label E- Interphase, this is the stage of growth and metabolic activity and occupies most of the cell cycle.
