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Writing Hand

Unit 4 -Water & Aquatic Food Production Systems & Societies

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Globe Showing Europe Africa

Unit 1 - Foundations Of Environmental Systems & Societies

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Herb

Unit 2 - Ecosystems & Ecology

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Flexed Biceps

Unit 3 - Biodiversity & Conservation

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Deciduous Tree

Unit 5 - Soil Systems & Terrestrial Food Production Systems & Societies

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Cloud

Unit 6 - Atmospheric Systems & Societies

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Thermometer

Unit 7 - Climate Change & Energy Production

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Briefcase

Unit 8 - Human Systems & Resource Use

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Bar-Chart

Internal Assessment

Imagine you&#39;re throwing a party, and you have to order pizza. The more guests, the more pizza you&#39;d need, right? Similarly, the more organic material (like food scraps at the end of a party) there is in water, the more dissolved oxygen it needs to be broken down. That&#39;s what BOD measures.

BOD is like a water health-checkup. It tells us how much dissolved oxygen water needs to break down organic material (think of stuff like dead plants or animal waste)

<ul>
	<li>High BOD = Lots of organic waste in the water = Less oxygen available for aquatic animals like fish. 🐟❌</li>
	<li>Low BOD = Cleaner water and more oxygen for aquatic life. 🐟✅</li>
</ul>

Think of water as your room. Sometimes you tidy up, but an hour later it&rsquo;s messy again. But if you had plants in your room and they&#39;re not doing well, that means it&#39;s probably been messy for a while!

<ul>
	<li>Using living organisms (like fish, plants, or insects) as indicators is like checking how well your plants are doing to see how long your room&#39;s been messy.</li>
	<li>Dipsticks give a snapshot, like glancing at your room once. It tells about NOW.</li>
	<li>Biotic indicators show how water quality&#39;s been over time. It&#39;s like your plant hinting, &quot;Hey, it&#39;s been bad for a while now!&quot;</li>
</ul>

<ul>
	<li>They provide a history of pollution levels. E.g., if certain fish can&#39;t survive because of pollutants, and they&#39;re not found in a water body, it suggests long-term pollution.</li>
	<li>Responds to long-term levels of chemicals and pollutants, not just short-term changes.</li>
</ul>

Real-world Example: In many rivers, if you find a bunch of mayflies, stoneflies, and caddisflies, it&rsquo;s a good sign! These little critters are sensitive to pollution. So, their presence indicates cleaner water. If they&#39;re missing but you find a lot of worms or leeches, it might hint towards more polluted waters. These worms can tolerate more pollution than the sensitive mayflies can.

<ul>
	<li>BOD is like an oxygen meter for water.</li>
	<li>High BOD = Bad news for fishes.</li>
	<li>Biotic indicators are like time-travelers, telling us the history of water quality.</li>
	<li>Presence or absence of certain organisms can indicate the cleanliness of water.</li>
</ul>

Now go and rock that exam, water warrior! 💧🌟🌍🚀

Aquatic Health: BOD & Biota

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Standard Level

Environmental Systems & Societies SL

Unit 4 -Water & Aquatic Food Production Systems & Societies

Decode Aquatic Health: BOD & Biota

Table of content

Biochemical oxygen demand (bod) 🌱

Key points

What is bod

Why is it important

Unlock the Full Content!

Unit 4 -Water & Aquatic Food Production Systems & Societies

Decode Aquatic Health: BOD & Biota

Table of content

Biochemical oxygen demand (bod) 🌱

Key points

What is bod

Why is it important

Unlock the Full Content!