Answer:
A carbon atom can form up to four covalent bonds as one carbon atom has four valence electrons (in outermost shell). It is a fact that the number of valence electrons in a atom determines the number of covalent bonds it will form. Thus, each electron in carbon atom is used to form four covalent bonds with various four atoms.
Explanation:
A bond between a carbon and hydrogen atom is a non-polar covalent bond. The non-polar covalent bond are the bonds between two atoms which share equal number of electron(s) with each other. Example: as in case of methane, where one carbon atom shares its 4 outer valence electrons with four hydrogens by sharing equal number of electron.
In contrast, polar covalant bond are the bonds between two atoms which share unequal number of electron(s) with each other. Thus these bonds are partially ionic.
The answer is a person removes their hand after touching a hot stove and a person turns their head toward the source of loud noise.
External stimuli are factors outside of the body that is taken in by receptors and will lead to a response. Examples of external stimuli include temperature changes, vision, hearing, tasting, smelling, and even sunlight for plants.
Learn more about External stimuli here:
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Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
<u>Answer:</u>
A mating of two people of medium height (where three genes control height): AaBbCc x AaBbCc produce <u>Seven</u> distinct phenotypes determined by the number of genes inherited.
Option: (D)
<u>Explanation:</u>
- Traits are the characters that we observe. When the parents AaBbCc and AaBbCc are crossed then AABBCC and aabbcc are two different dominant and recessive genomes seen in the offspring.
- Offspring with AABBCC will be height whereas aabbcc will be dwarf. There will be offspring with different heights depending upon the dominant and recessive gene present in them.
- Another genome produced are AABBCc/AaBBCC/AABbCC, next will have four dominant and 2 recessive, next will have 3 dominant and 3 recessive AaBbCc, next will have 2 dominant and 4 recessive, one dominant and five recessive. All together offspring produced will be 64
