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What is the difference between the perfect tense and the preterite tense?

The preterite and perfect tenses are both used when an action has been completed . Then, what is the difference? Well, their use depends on regional differences and varieties of Spanish. But don't panick! It...
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Answered by Joanes B. • Spanish tutor
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Describe how elements of the periodic table are arranged relating to their atomic structure. (6 marks)

Elements in the periodic table are arranged by increasing atomic number (number of protons). Atomic number of elements steadily increases across a period (horizontal rows of the periodic table). Elements in ...
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Answered by Jake G. • Chemistry tutor
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Explain three differences between particles in a solid state and particles in a gaseous state.

Particles in a solid state are packed very close together whereas in a gaseous state they are very far apart.Particles in a solid state have a regular, structured pattern whereas gaseous particles are random...
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Answered by Frankie L. • Chemistry tutor
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Each amino acid contains a different R group specific to the amino acid. Describe how the R group of an amino acid contributes to the tertiary structure of a protein. (4 marks)

Cysteine contains an S atom in its R group. Where 2 molecules of cysteine are found together, strong covalent bonds or "disulfide bridges" can form between the two S atoms (S=S). R groups may have ...
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Answered by Jake G. • Biology tutor
20064 Views

Describe the process of aerobic respiration.

Respiration is the process by which cells make energy. Aerobic respiration uses oxygen to make energy. Respiration involves a series of reactions. The overall equation for the reaction is:Oxygen + Glucose —&...
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Answered by Madlen H. • Biology tutor
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