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0:01 Hi everyone, this is teacher Jane of Teach Talk where learning is fun and easy. If this is your first time watching our videos, don't forget to subscribe and click that bell button so you'll get notified on our next videos. Welcome to Shenha amazing science concepts from grade 7 to grade 12 topics in general science, biology, chemistry, physics and earth science. [Music]
0:50 Materials that make up living organisms find their way back to the physical environment and are reused by other living organisms. Such cyclic process of materials ensures the continuous supply of much needed materials to sustain life in ecosystems. Biogeeochemical cycles biogeeochemical cycles. We are going to discuss four out of the biogeeochemical cycles that occur in nature. We are going to discuss water or hydraologic cycle, oxygen carbon dioxide
1:36 cycle, nitrogen cycle at phosphorus cycle. Simula water or hydraologic cycle. To explain this cycle, firstang body of water just like this small pond evaporation from the bodies of water release water vapor into the atmosphere. After that, the process of condensation changes water vapor back into liquid water forming clouds above. Then they return back to Earth in a process called precipitation which may be in a form of rain, snow and other
2:22 forms of precipitation. And when it precipitates or it rains, the water on the ground infiltrates into the soil in a process called infiltration. When excess rainwater can no longer sufficiently infiltrate the soil, it flows or runs off over the land surface. It may stay stagnant on the land or it may combine to other bodies of water. After this evaporation will occur again, hence the water cycle. Aside from these processes, we also have one process which occur among plants. It is transpiration. Transpiration is simply the evaporation of water from the leaves of the plant.
3:09 It also contributes to the amount of water vapor in our atmosphere. That's just a very brief explanation of the water cycle. Now let's proceed to the next one. The oxygen carbon dioxide cycle. We humans use oxygen for our bodily processes. Just like most living organisms, animals and plants also breathe in oxygen. Let's have another trivia. Do plants breathe in oxygen? Yes, you heard it right. Plants also
3:54 breathe in oxygen. Most students have learned that plants take up carbon dioxide from the air and produce oxygen as byproduct of a process called photosynthesis. Photosynthesis occurs in the chloroplast of a plant cell. But it is less well known that plants also need oxygen. Plants like animals have active metabolism fueling all bodily activities. For this almost all organisms need oxygen to create energy. And this happens in a complex process called cellular respiration. In cellular respiration, oxygen
4:40 interacts with glucose to produce energy. We will be having a separate video discussing cellular respiration. Cellular respiration that uses oxygen occur in the mitochondrian. As you can see, the plant cell has a mitochondrian, proving that plants really need oxygen. But how do plants exactly breathe? How do we get the necessary oxygen for the plant cells? Gases such as oxygen and carbon dioxide enter or leave a plant through tiny holes called stomata. Sandakitang stomata. They are mostly found in the underside of its leaves.
5:26 Here we can see the stomata in action. They are the tiny holes on the leaf. [Music] Going back to the oxygen and carbon dioxide cycle. When we exhale, we release carbon dioxide which is then used by plants in photosynthesis. They use this to create simple sugars or food. as a byproduct they release oxygen and this oxygen returns to the atmosphere. Now this free oxygen is the one which we inhale. Now this free oxygen in the atmosphere in our environment is the one which we inhale back for our metabolic processes
6:11 and then the cycle goes on. We are done with the water and oxygen carbon dioxide cycle. Now let's proceed to the third major biogeeochemical cycle, the nitrogen cycle. Air is about 78% nitrogen gas. Living things just like us need nitrogen for making protein since protein is the basic organic material in living organisms. However, directly nitrogen atmosphere. This nitrogen has to be converted into compounds called nitrates. In the process of converting certain
6:57 bacteria called nitrogen fixing bacteria and algae in the soil can convert nitrogen into nitrates in a process called nitrogen fixation. In this picture we can see the nitrogen fixing bacteria in the root nodules of some plants. Plants absorb nitrates through their roots. When animals eat plants, they take in plant proteins containing nitrogen. Then they convert this into animal proteins. When plants and animals die, they release nitrogen compounds. What happens next? Another
7:43 group of useful bacteria called nitrifying bacteria convert these nitrogen compounds first into nitrites N O2 and then into nitrates. These nitrates can be assimilated into the soil and be used by plants and animals again. Still, another bacteria called the nitrification bacteria release nitrogen from the nitrates back into the atmosphere, thus completing the cycle. Then the nitrogen in the air will be used again. The first three cycles are the ones most commonly found in science books. But just for some additional information, we're also going to discuss a fourth
8:29 cycle, which is the phosphorus cycle. Rocks contain phosphorus. The weathering of rocks, for example, those found in the mountains will cause the formation of underground phosphate reserve. This phosphate will be absorbed by plants and when plants are eaten by animals they will also be incorporated into the body of the animals. When these plants and animals die they are decomposed and broken down and the phosphate in these dead organisms will be released back to the environment adding to the phosphate reserve on land. This phosphate reserve can leech toward
9:15 a body of water. Aside from that, the phosphate containing fertilizers from farmlands can also run off to bodies of water. Additionally, the phosphate from the weathered rocks can be carried through the water and contribute to the formation of phosphate sediments in the underwater and consequently the underwater phosphate reserve. These processes will soon contribute to the formation of a new rock. Then this new rock which contains phosphorus will undergo weathering releasing phosphate back into the environment and then the phosphorus cycle goes on.
10:04 Biogeeochemical cycles are said to be pathways of matter. Why is that so? because they are any of the natural pathways by which essential elements of living organisms are circulated. They show that matter is recycled in any of these cycles. And because of these biogeeochemical cycles, the essential elements are brought back and used by living organisms. That's about it for our biogeeochemical cycles. Let's have a quick recap of what we have discussed in this video. In this shame amazing episode, we focused on the biogeeochemical cycles. We talked about the water cycle, oxygen
10:52 carbon dioxide cycle, also about the nitrogen cycle. And lastly, we discussed a little about the phosphorus cycle. It's good time. To check how much you have learned in this video, we are going to have a short threeinut quiz. After 3 minutes, you should check from 1 to 5. Let's start.
14:24 Times up. Let's start with number one. A process that occurs when water becomes water vapor. And keyword clue I water vapor. The answer is evaporation. Number two, water that flows over the land surface. Key words flows over land. This is surface runoff penetrate water so soil it will flow over the land surface. Number three a process where certain bacteria convert nitrogen gas into nitrates. These bacteria are nitrogen fixing bacteria. So process nitrogen fixation.
15:11 Number four, tiny openings or pores in plant tissue that allow for gas exchange. Gaso can be carbon dioxide or oxygen. What is the term for these openings? It's stomata. Opening its sto. Last number five. A process that uses carbon dioxide for plant food production. From the choices legumes at nitrification is a nitrogen cycle. We will be focusing on photosynthesis and respiration which among these two produces food for the plant and uses carbon dioxide. It is photosynthesis.
15:57 In contrast, respiration uses oxygen to release energy. That's the end of our quiz. Please comment your score over five so that we can check them out. That ends our Shanch amazing episode for today. Don't forget to subscribe, like and share this video to your friends so that we can learn together. Bye. [Music] Heat. [Music]
