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3.3 Vitamin D

The main role of vitamin D is to facilitate the uptake of calcium from food, through the lining of the small intestine into the blood. It also controls the deposition of calcium in the bones during growth and maintains adult bone structure. If vitamin D is deficient, with less calcium available, the skeleton fails to develop normally. The most obvious symptom is the bowing of the leg bones in children, producing the condition called rickets (Author(s): The Open University

2.2 Vitamin A

Activity 4

Look back at Table 1 and identify the foods that contain vitamin A. On the basis of this information, try to predict where vitamin A is stored in the human body.

Author(s): The Open University

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1.1 Introduction to vitamins and why we need them

Before the 19th century, one of the hazards of long sea voyages was a condition called scurvy, whose symptoms were loss of hair and teeth, bleeding gums, very slow healing of wounds, and eventually death. Hundreds of sailors and explorers died from scurvy until a Scottish physician, James Lind, in the 1750s discovered that adding a daily portion of citrus fruit to the rations of those at sea could prevent the condition, whereas adding cider, vinegar or various other substances that he tested,
Author(s): The Open University

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Introduction

Genes are units of inheritance that contribute to a person’s behaviour and health. In this unit you will learn what genes, DNA and chromosomes are and how they combine to make the human genome. You will also learn how the principles of inheritance work, the effect that our genetic make-up has on health, and how genetic material is passed on from generation to generation.

This unit is an adapted extract from the course Author(s): The Open University

Learning outcomes

By the end of this unit you should be able to:

  • understand the application of basic principles in geometrical optics;

  • appreciate the phenomena relating to the wave nature of light.


Author(s): The Open University

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1.2.3 The physiological and behavioural levels

Anticipation of winter

If organisms are to survive winter, they must be well prepared for cold weather and sometimes for reduced supply of food. Physiological changes such as shedding leaves and building up fat reserves, and behaviours such as hoarding food, must be completed before winter begins. In order to be prepared, organisms need to anticipate the onset of winter, which is done in two ways, each of which has its own associated physiological mechanisms. First, they could re
Author(s): The Open University

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1.2.2 The cellular level

The water in plant and animal tissues has two major components: the intracellular fluid (within cells) and the extracellular fluid, which fills the spaces between cells. When a tissue freezes, ice typically forms first in the extracellular fluid. Ice formation has two harmful effects:

  1. It disrupts cell walls and cellular membranes.

  2. The formation of ice in extracellular fluid effectively removes water from solution, thereby increasing its
    Author(s): The Open University

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Learning outcomes

After studying this unit you be able to:

  • discuss the sequence of the events that are believed to have taken place in the history of the Universe, particularly the particle reactions that occurred in the first few minutes after the Big Bang, and the role of unified theories in explaining those events;

  • manipulate large and small numbers in scientific notation, and calculate values for quantities when given appropriate numerical information.


Author(s): The Open University

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3.3.6 The House of Lords

The House of Commons and the House of Lords must finally agree on the text of a Bill. If a Bill started life in the House of Commons it is now passed to the House of Lords where it goes through all the stages outlined above. "If the House of Lords votes against a Bill it can go back to the House of Commons and become law if the House of Commons passes it for the second time. The reason for this is that the House of Lords is not an elected body and its function is to refine and add to law rath
Author(s): The Open University

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1.4.1: Price ratios

In Chapter 1, Section 1.4 of the Calculator Book, you saw that multiplying a price by, say, 1.30 is equivalent to increasing it by 30%. Similarly, multiplying a price by 0.94 is equivalent to decreasing it by 6%. The figures 1.30 and 0.94 are called price ratios. In Table 6, the price of a loaf of bread went up from 50p to 65p. The price
Author(s): The Open University

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1.9.4 Video task: Taking the A train

Now watch the video.

Video, Click to watch part two

Download this video clip.