A landform is a natural feature of the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Typical landforms include hills, mountains, plateaus, canyons, and valleys, ... Oceans and continents exemplify the highest-order landforms.
Answer:
The effort put by scientist and sailors about earth is that they keep on going round the earth and putting their lives in danger and some even give their lives.
Explanation:
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Answer:
Explanation:
1- the purpose of blood flow-circulatory system- is to convey Oxygenated blood, oxygen bonded with haemoglobin in the RBC with Nutrients - and distributed these through the arteries and capillaries away from the heart, to reach the cells and tissues, and transported the wastes of theses cells and tissues , with C02 through the veins back to the heart and the kidney.
2. During diastole,deoxygented blood from the inferior and superior vena cavae entering the R.atrium, passes through the tricuspid valve into the Right Ventricle. Simultaneously, oxygenated blood returning through the pulmonary veins enters the left Atrium,emptied through the bicuspid valve into the Left.Ventricle.
During systole, the two ventricles contracts. The Right ventricle contracts, the pressure of the blood forces the tricuspid valve to close,and therefore de -oxygenated blood pushes the pulmonary valves to open and blood passes through the pulmonary artery to reach the lungs where exchanges of oxygen with carbon dioxide occurs.The blood is now oxygenated and returns to the left atrium via pulmonary veins.
Simultaneously, the left ventricle contracts,the oxygenated blood it contains forced the bicuspid valve to close so that blood is forced through the aortic valve to empty into the aorta into the systemic circulation,branches of the carotid artery supplies the heart from the aorta.
The Whole cycle continues.
Answer:
Enzymes are one kind of protein which functioning as catalyst that speed up reactions by lowering activation energy.Enzyme accelerate a reaction without altering its chemical equilibrium.
Explanation:
Energy which is required for start a biochemical reaction is called activation energy.Activation Energy helps to jump and start a thermodynamically favorable reactions.
Enzymes can many way to its activation energy.
1. The enzyme may hold the substrates in such a way as to distort the substrate bonds closer to their form in the transition state. This reduces the amount of energy needed to complete the transition.
2.Enzyme create a charge distributor which opposite of transition state his lowers the energy of the transition state and decreases the activation energy.
3.The enzyme may reduce the reaction entropy by bringing substrates together in the correct orientation to react.
4. The enzyme may provide a completely different chemical pathway for the reaction. It may form new bonds in the ES complex that would be difficult to form without the enzyme.
Answer:
Natural selection is one of the mechanisms by which an organism evolve. In the natural selection when the trait of an organism allows the organism to grow and reproduce in an environment and nature selects it, it is then passed on to the generations and become permanent.
Artificial selection is also one of the mechanism of evolution in which instead of nature, the selection is made by humans like the breeding experiments on dogs and plant crops.
The artificial selection and natural selection are interlinked as in the artificial selection the trait selected by the humans were also selected by nature like the case of crops, the crossing between desired plants produced results which were useful to the humans but grew and reproduced only when the environment selected it to grow and reproduce.
