These are the answers to the following questions:
1. In what type of rocks would geologists most likely find evidence of past life forms?
-igneous rocks
2. The physical, chemical and biological laws that opeate today have also operated in geologic past. This statement relates to the principle of
-cross-cutting relationships
3. In general, the law of superstition states that in an underformed sequence of sedimentary rocks, each layer is
-older than the one below it
4. If a layers of sandstone is in contact with a mass of granite that contains small pieces of the sandstone, which rock is older?
-It is not possible to determine which rock is older from this information
The study of onion root tips is widely known for the clear appearance of the stages of mitosis since the chromosomes are large and are clearly visible. They are easily stained with the stainer and are visible clearly under the electron microscope. The phase of mitosis are
Interphase
Prophase
Metaphase
Anaphase
Telophase and
Cytokinesis
Each of these phases show the different stages in which the division of one cell into two daughter cells takes place. The cytokinesis is the final phase in the mitosis cell division. This is the part of cell division process during which the cytoplasm of the cell divides into two equal parts and forms into two daughter cells.
During the cytokinesis process, the spindle apparatus partitions and transports the duplicated chromatids and moves into the cytoplasm of the dividing daughter cells. In this process a dividing structure called the cell plate is formed to distinguish the daughter cells. This cell plate later grows into a double layered cell wall which then splits the parent cell into two separate cells.
Hence the option D is the right answer
the first answer as blood needs to be oxygenated to be passes round the body then when its deoxgenated it will return to the heart to be pumped around the body again
Answer: zap70, ITAM.
Explanation:
An antigen is any substance that is capable of stimulating an immune response by activating lymphocytes, which are the body’s infection-fighting white blood cells. Examples of antigens could be proteins that are part of bacteria or viruses or components of serum and red blood cells from other individuals, all of them are foreign antigens originated outside the body. However, there can also be autoantigens (which are self-antigens), originated within the body. In normal conditions, the body is able to distinguish self from nonself. <u>And the antigens that represent a danger induces an immune response by stimulating the lymphocytes to produce antibody or to attack the antigen directly</u>. This is called an antigenic stimulation of the immune system.
ZAP-70 (Zeta-chain-associated protein kinase 70) is a protein that is part of the T cell receptor, thereby it plays a critical role in T-cell signaling. When the TCR (receptor of T cells) is activated by the presentation of the specific antigen through the MHC, a protein called Lck acts to phosphorylate the intracellular CD3 chains and the ζ chains of the TCR complex, allowing the binding of the cytoplasmic tyrosine kinase, ZAP-70. Lck then phosphorylates and activates ZAP-70, which in turn phosphorylates another molecule in the signaling cascade called LAT (short for Linker of Activated T cells), a transmembrane protein that serves as an anchor site for several other proteins. The tyrosine phosphorylation cascade initiated by the Lck culminates in the intracellular mobilization of calcium ion (Ca2+) <u>and the activation of important signaling cascades within the lymphocytes.</u> These include the Ras-MEK-ERK pathway, which is based on activating certain transcription factors such as NFAT, NFκB and AP-1. These transcription factors regulate the production of of certain gene products, most notably cytokines such as interleukin-2 that promote the long-term proliferation and differentiation of activated lymphocytes.
The ITAM motifs (immunoreceptor tyrosine-based activation motif) are sequences of four amino acids present in the intracellular tails of certain proteins that serve as receptors within the immune system. Thus, <u>some receptors such as the TCR have ITAM sequences that, when activated, trigger an intracellular reaction based on consecutive phosphorylations</u>. Kinases are recruited for this purpose.
So, ZAP-70 is a protein tyrosine kinase with a role in T-cell receptor signal transduction. During T-cell activation, ZAP-70 binds to ITAM and becomes tyrosine phosphorylated. The binding of ZAP-70 to the phosphorylated ITAM is able to activate its kinase activity, <u>and relieves the inhibition of the transcription factor which regulates genes that are involved in the immune reaction</u>.
Answer:
A. Air
Explanation:
Abiotic factors are things that are not living.
Air can be found in a rain forest ecosystem, as it can be found in all ecosystems, but it is not living.
On the other hand, algae, flowers, and animals are biotic instead of abiotic because they are living things.
So, A is the correct answer.
