Photosynthesis And Cell Respiration In Living Things Biology Essay

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Light is energy, electromagnetic. Photosynthesis is when plants convert energy from the sun. Plants create organic molecules that they use as fuel from this process. The molecules of chlorophyll which is in the chloroplasts absorb energy from the sun. Instead of breathing in oxygen and breathing out carbon dioxide like animals, plants take in carbon dioxide from the atmosphere. Plants take in water from the ground up through their roots. Below is two diagrams, the first is showing the processes of photosynthesis simply, in a plant. The second is showing the chemical equation of photosynthesis. This chemical equation means that carbon dioxide from the air and water mix when sunlight is present to make sugars; oxygen is released also, because of this reaction.

http://www.homestead-farm.net/art/kidsArt/photosynthesis-color.jpg

Allnutt, B and M, (Date unknown)

http://media.wiley.com/Lux/50/24150.nce004.jpg

In the process of photosynthesis, the energy from the sun splits the water molecules into hydrogen and oxygen. The oxygen molecules are given off by the plant and shed into the atmosphere. Sunlight is converted to chemical energy in the form of ATP. ATP is the main energy-storing molecule in living things. ATP is then shifted through the chloroplast and used to supply the chemical energy needed to make other metabolic reactions. Some of the ATP is used to start the metabolic reactions in the change of CO2 into sugars and other compounds. These reactions are called photochemical or light reactions (Light dependant reactions).

Enzymes in the plant then start the mix of hydrogen and carbon dioxide to make a carbon compound that is called an intermediate. An intermediate is a compound used to carry on a process to make a completely different compound.

In plants, the intermediate is named phosphoglyceraldehyde (PGAL). PGAL goes on in the process to make glucose, which the plant needs as fuel to survive. These chemical reactions are called carbon-fixation reactions, or dark reactions to understand them differently from the light reactions above. These chemical reactions can also be called The Calvin cycle. Atoms of carbon are put into lasting compounds which can be used carefully instead of being loose around the cell at random.

When the plant has made more glucose than it needs to use, it combines glucose molecules into bigger carbohydrate molecules which are called starch. These starch molecules are stored in the large vacuoles in the plant cells. When important, the plant can break up the starch molecules to retrieve glucose for energy or to create other compounds: proteins, nucleic acids, or fats.

Cell respiration is the appointed metabolic reactions and developments that occur in the cells of living things to change in to biochemical energy from nutrients into ATP. In cells, Mitochondria are the power house of the cell because it forms most of the cell's stock of ATP, and used as a source of chemical energy. Respiration is the opposite of photosynthesis, and is stated by the equation shown in diagram below.

C6H12O6+6O2 ----------> 6CO2+6H2O+36ATP

This equation shows that oxygen mixed with sugars to break molecular bonds, releasing the energy, in the form of ATP within those bonds. Accompanying the energy released, the results of the reaction are carbon dioxide and water. 

In eukaryotic cells, cell respiration starts with the results of glycolysis being moved into the mitochondria. A vast amount of metabolic pathways in the mitochondria produce in the further breaking of chemical bonds and the deliverance of ATP. CO2 and H2O are the end results of these reactions. 36 ATP means the highest amount of produce per glucose molecule which is metabolised.

Photosynthesis is a reduction-oxidation reaction. Respiration is also a reduction-oxidation reaction. In respiration energy is released from sugars when electrons identified with hydrogen are moved to oxygen, and water is made. The mitochondria make use of the energy which has been released in this oxidation, to arrange ATP.  In photosynthesis, the water is split not made, and the electrons are relocated from the water to CO2, because of this the energy is used to break the CO2 into sugar. 

Evaluate the roles of photosynthesis and cell respiration in the carbon and water cycles.

In the water cycle, energy is provided by the sun, which will make evaporation. Evaporation is when liquid water turns gaseous. In plants water is absorbed through the roots and then moved to the leaves where it evaporates, this is called transpiration. In plants and animals the breaking down of sugars (carbohydrates) to make energy is called respiration. This break down in sugars makes carbon dioxide and water as waste produce. Photosynthesis does the opposite and uses carbon dioxide and water to make sugars (carbohydrates). Over leaf is a diagram showing the water cycle in full.

http://www.cleanwatercampaign.com/images/kids_watercycle_big.jpg

Author unknown (Date unknown)

In the carbon cycle respiration makes carbohydrates and oxygen into carbon dioxide, water and energy. Photosynthesis makes carbon dioxide and water into carbohydrates and oxygen. What goes in to respiration are the outputs of photosynthesis and what goes in to photosynthesis are the outputs of respiration. Below is a diagram of the carbon cycle.

http://www.farmingfutures.org.uk/sites/default/files/uploads/diagrams/carbon-cycle.gif

Author unknown (Date unknown)

4.1 Explain the roles of xylem and phloem vessels in plants.

In vascular plants, xylem is a tissue that transports water up the stem. In trees, it develops wood. Working together with phloem, xylem is one of only two transporting tissues in plants. The cell walls of xylem cells collect most of their strength from lignin, a chemical which is only made by plants. 

Xylem sap only moves from the roots to the leaves. It travels in vast amounts, instead of by diffusion through cells. Three reasons cause xylem sap to flow.

The soil solution is weaker than the cytoplasmic matrix of the plant root cells which will make root pressure.

Capillary action helps sap to flow up the narrow Tracheid's.  Below is a diagram showing Tracheid's.

http://www.cactus-art.biz/note-book/Dictionary/aaa_Dictionary_pictures/xylem_Vessel.jpg

The last reason of xylem sap is transpiration pull. This is the opposite of root pressure, which is caused from the transpiration of water from the leaves. 

In vascular plants, phloem is the living tissue that moves nutrients, mostly sugar, to all parts of the plant where it is needed. In trees, the phloem is the most inner layer of the bark.

The phloem's main job is with the moving of soluble organic material which is made during the process of photosynthesis, which is called translocation. Below is a diagram of plant showing phloem.

designelement

Author unknown (Date unknown)

Plants have vascular tissues (xylem), which moves water and minerals up from the roots to the leaves, and phloem, which transports sugar, amino acids, and hormones up and down the whole of the plant.

In the leaves, plants have veins. In which nutrients and hormones travel to the cells located in the leaf. Sap is the combination of water and minerals that travel through the xylem. Carbohydrates travel through the phloem. The main reason of the xylem and phloem is to make sure all cells of the plant are hydrated and nourished. Below is a table showing the comparison of xylem and phloem.

Xylem

Phloem

Active/passive transport

Passive

Active

Transportation method

Transpiration

Translocation

Reason

Water and minerals to leaves

Sugars and food to the plant

Source

Roots

Leaves

Location

Leaves

The plant

Direction of flow

Up

Up and down

Made of

Dead cells

Living cells

Cell wall thickness

Thick

Thin

Cell wall made of

Lignin

Cellulose

Permeability

Impermeable

Permeable

Cytoplasm

None

Cells have strands of cytoplasm

Based on image from GCSE Bite size Author unknown (Date unknown)

4.2 Discuss the factors which influence the processes of water and nutrient transport in plants.

Plants create fuel through Photosynthesis but this occurs in their leaves, Plants need to absorb nutrients and water through their roots, so plants have to get water and nutrients from the soil up through their stems to the parts of the plant which is above the ground.

Plants have vascular tissues (xylem), which moves water and minerals up from the roots to the leaves, and phloem, which transports sugar, amino acids, and hormones up and down the whole of the plant.

In the leaves, plants have veins. In which nutrients and hormones travel to the cells located in the leaf. Sap is the combination of water and minerals that travel through the xylem. Carbohydrates travel through the phloem. The main reason of the xylem and phloem is to make sure all cells of the plant are hydrated and nourished.

In the root cells, there are many more minerals, than there is in the soil surrounding the plant. This causes root pressure, which pushes water out of the root, out of the xylem, as more water and minerals are absorbed into the root from the soil. This force results of tiny droplets on the ends of leaves in the early morning. (In guttation)

There are factors which can influence the processes of water and nutrient transport in plants such as,

Light intensity: More light results in faster photosynthesis as there is more energy being made in to ATP.

Carbon dioxide concentration: Higher levels result in a high rate. 

Temperature: Within all chemical reactions, lower temperatures slow down the reaction but too high a temperature can be harmful in photosynthesis, in transportation of minerals and water to high a temperature could result in dehydration.

Availability of water:  Water is very important to all organisms without water the plant will wilt and die.

Availability of nutrients:  Nutrients are equally important and without nutrients the plant will wilt and die an attributing factor could be poor quality soil. 

Environmental factors: Where the plant is planted can have limits for light and water resources. Environmental pollutants (dust, ash) may drop onto the leaves and smaller the chances of photosynthesis. 

Plants need air, water, soil, minerals and space in which to grow without any of these important factors it will influence the processes of water and nutrient transport in plants. Plants need to photosynthesise for fuel (sugars) to survive.

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