Answer:
Cleavage is a process in which cell is divided into several parts without increasing in size. There are 4 stages of cleavage i. e. 2-cell, 4-cell, 8-cell and 16 cell stages. 2 cell embryo cleavage occurs after 30 hours of fertilization. 4 cell embryo cleavage occurs after 48 hours. 6 cell embryo cleavage occurs on third day of fertilization. 8 cell embryo cleavage occurs on fourth day of fertilization and more than 100 cells are formed.
In HIV-infected patients, there is a gradual loss of CD4+ T cells over time. These cells, also called T helper cells, organize the immune system's attack on disease-causing invaders, like Salmonella.
Answer:
B (active transport using ATP)
Explanation:
Movement of substances normally occur in the direction of concentration gradient/difference i.e. the difference in concentration of a substance across a membrane. Letting molecules diffuse or pass down their concentration gradient does not require energy but pumping those molecules against gradient requires energy in form of Adenosine triphosphate (ATP). This process is called Active transport.
In order to perform certain cellular processes, cells need to move substances from their surroundings into the cell across their cell membrane. Moving this substances against the concentration gradient between the cell membrane and its extracellular fluid requires energy (ATP).
An example is the sodium-pottasium pump employed by animal cells in which they expend energy to move K+ molecules into the cell and Na+ molecules outside the cell against the concentration gradient of their cell membrane and extracellular solution.
2. A Mendelian trait is caused by a single gene. 3. Traits can be dominant or recessive and recur in a predictable pattern in subsequent generations. ... Autosomal Recessive Inheritance: Autosomal recessive traits can skip generations and can affect both sexes.
Answer: An essay is a common type of academic writing that you'll likely be asked to do in multiple classes. Before you start writing your essay, make sure you understand the details of the assignment so that you know how to approach the essay and what your focus should be. Once you've chosen a topic, do some research and narrow down the main argument(s) you'd like to make. From there, you'll need to write an outline and flesh out your essay, which should consist of an introduction, body, and conclusion. After your essay is drafted, spend some time revising it to ensure your writing is as strong as possible.
