Name: Date: - 1. A pair of shared valence electrons is referred to as a(n): A) i
ID: 267968 • Letter: N
Question
Name: Date: - 1. A pair of shared valence electrons is referred to as a(n): A) ionic bond. B) hydrogen bond. C) van der Waals interaction. D) covalent bond. E) hydrophobic effect. 2. When we say that the cell is the fundamental unit of life, we mean that: A) all living things are made up of one or more cells. B) the smallest entity that can be considered living is a cell. C) a single cell can carry out all life processes. D) life doesn't exist in the absence of cells. E) All of the answer options are correet. 3. The reducing agent during the Calvin cycle is: A) NADPH B) ATP C) oxygen D) NADH E) FADH2 If an atom has three electrons, how many occupied orbitals will the atom have, and horw many electrons will be in each? A) The atom will have two orbitals, One will have two paired electrons, and the other B) C) D) will have one unpaired electron. The atom will have three orditals, One will have three pairs of electrons and the other will have one unpaired electon The atom will have two orbitals, one electron in the inner orbital and two electrons in the outer orbital The atom will have three orbitals one electron in each orbital 5. Sometimes, atoms gain or lose particles. The loss of which of the following would result in a change of overall electrical charge? A) protons only B) electrons only C) neutrons only D) protons or neutrons E) protons or electrons F)Explanation / Answer
1. A covalent bond is formed by the sharing of a pair of valence electrons. So, the correct option is option D, Covalent bond.
2. A cell is the fundamental unit of life. All living things are made up of one or more cells and a cell can be considered as the smallest living entity. A single cell can carry out all life processes and life does not exist in the absence of cells. So, the correct option is option E, All of the answer options are correct.
3. Calvin cycle occurs in C3 plants. In Calvin cycle carbon dioxide is fixed to form sugars. The reducing agent in Calvin cycle is NADPH. NADPH donates its high energy electrons for the formation of sugars. So, the correct option is option A, NADPH.
4. If an atom has three electrons, the atom will have two orbitals. One orbital will have two paired electrons, and the other orbital will have one unpaired electron. So, the correct option is option A, The atom will have two orbitals. One will have two paired electrons, and the other will have one unpaired electron.
5. The number of protons does not change in an atom. If an atoms loses neutrons, an isotope of the atom will be formed. If an atom loses or gains electrons, the overall charge on the atom will be changed. So, the correct option is option B, Electrons only.
6. Photosystem II absorbs light from Sunlight and transfers it to photosystem I that uses the light energy absorbed by photosystem II to generate ATP and NADPH that are utilized during the fixation of carbon dioxide to form sugar. Photosystem I and photosystem II differ in H+ production, and electron donors and acceptors. So, the correct option is option C, H+ production, and electron donors and acceptors.
7. During cellular communication, receptors on the outside of the cell bind to specific signal molecules. This activates the cell-surface receptor which then transfers the signal to the interior of the cell. Inside the cell, the transmitted signal is amplified as a series of proteins are activated in sequence, affecting cellular activities according to the type of signal involved. A cell returns to its normal activities after the signal has exerted its effect. So, the correct option is option A, The cell does not return to its normal activities after the signal has exerted its effect.
8. A protein on the cell surface known as the receptor protein binds to a signaling molecule during cellular communication. The receptor protein is present on the surface of a responding cell. So, the correct option is option C, A receptor protein.
9. An atom with three electrons has two occupied orbitals. One orbital will have two paired electrons and the other orbital will have one unpaired electron. So, the correct option is option B, Two occupied orbitals, one of which has two electrons and the other has one.
10. Formula for calculating the number of neutrons = mass number - atomic number (number of protons)
Number of neutrons in Oxygen = 16 - 8 = 8.
So, the correct option is option D, 8.
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