What is meant by an enzyme-controlled metabolic pathway?

It is a sequence of reactions in which each step is catalysed by its own specific enzyme, and the product of one reaction becomes the substrate of the next.

Explain why two molecules of ATP are used at the start of glycolysis.

Adding the phosphate groups destabilises the sugar and lowers the activation energy for splitting it, and the charged phosphate also prevents the sugar leaving the cell.

What happens to hexose bisphosphate in the lysis stage of glycolysis?

It is split into two molecules of triose phosphate, each with three carbon atoms.

OCR A-Level Biology B H422

The Developing Cell: Cell Division and Cell Differentiation

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The Developing Individual: Meiosis, Growth and Development

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Cells and Microscopy

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Water and Its Importance in Plants and Animals

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Proteins and Enzymes

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Nucleic Acids

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Patterns of Inheritance

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Plant Reproduction

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The Nervous System and the Identification and Consequences of Damage

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The Effect of Ageing on the Nervous System

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The Heart and Monitoring Heart Function

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Transport Systems in Mammals

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Gas Exchange in Mammals and Plants

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Transport Systems in Plants

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Cellular Respiration

Glycolysis and the link reaction

3 things to know
Components 01, 02 and 03

Overview

Recall questions on enzyme-controlled metabolic pathways, the phosphorylation, lysis and oxidation stages of glycolysis, dehydrogenases and NAD, substrate-level phosphorylation, the net yield of glycolysis, and the link reaction in the mitochondrial matrix and the role of coenzyme A.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Evaluation

Give two advantages of releasing the energy in glucose through a long metabolic pathway rather than in a single step.

Key term

Where in the cell does glycolysis take place?

Process

Describe the phosphorylation stage of glycolysis.

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by an enzyme-controlled metabolic pathway?
Model answer
It is a sequence of reactions in which each step is catalysed by its own specific enzyme, and the product of one reaction becomes the substrate of the next.
2
Give two advantages of releasing the energy in glucose through a long metabolic pathway rather than in a single step.
Model answer
Energy is released in small amounts that can be captured as ATP rather than lost as heat, and the rate of the whole pathway can be controlled by regulating individual enzymes.
3
Where in the cell does glycolysis take place?
Model answer
In the cytoplasm, where its enzymes are dissolved in the cytosol.
4
Describe the phosphorylation stage of glycolysis.
Model answer
Glucose is phosphorylated using a phosphate group from ATP, and the product is phosphorylated again using a second ATP, giving a hexose bisphosphate.
5
Explain why two molecules of ATP are used at the start of glycolysis.
Model answer
Adding the phosphate groups destabilises the sugar and lowers the activation energy for splitting it, and the charged phosphate also prevents the sugar leaving the cell.
6
What happens to hexose bisphosphate in the lysis stage of glycolysis?
Model answer
It is split into two molecules of triose phosphate, each with three carbon atoms.

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The Developing Cell: Cell Division and Cell Differentiation

The Developing Individual: Meiosis, Growth and Development

The Development of Species: Evolution and Classification

Cells and Microscopy

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measles and .

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ABrain tissue is metabolically expensive.

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