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Water in PlantsBy: Maisha Loveday 8C

Introduction

Plants are living things that can create their own food by photosynthesis using water, chlorophyll, carbon dioxide and light energy from the sun. There are several key factors that help the plant do this as well though. Water, chlorophyll, sunlight and carbon dioxide are only the first part. The distribution of the ingredients in the plant is another part of the process.

Basic Water Movement in a Plant

You can see that the water starts at the roots, goes up the stem through the xylem tubes and then diffuse into the air from the leaves.

The Roots & Tubes

Water gets absorbed into the ground when it rains. The roots, which are found in the bottom of the plant, are used to anchor the plant so it doesn’t fall and to take in water and minerals for the plant. The root hairs are the part of the roots that take in the most water through osmosis, which is when the water in the soil has a weak solution of salts, and the water passes form the soil into the root hair because the cell sap in the root hair cell has a stronger solution. “osmosis is the flow of water down a concentration gradient.” http://en.allexperts.com/q/Molecular-Biology-1353/2009/10/Osmosis.htm. Inside the roots there is a cortex, which is used to store food as starch. In the roots and stem there are tubes or veins called the xylem and phloem. These tubes are used to distribute water and food around the plant. The xylem carries water and minerals from the roots up to the leaves and the phloem carries food made in the leaves all around the plant. So the water and mineral from the roots travel up through the xylem to the leaves.

Xylem and Phloem Diagram

http://www.bbc.co.uk/schools/gcsebitesize/science/images/addgateway_plant_stem.gif

Stem

The stem is basically the part of the plant that the leaves, flowers and roots are connected to. The stem doesn’t actually take in carbon dioxide, water, or sunlight but the xylem and phloem tubes are in it so it used to help water, nutrients and food travel all around the plant in both directions. Also, in environments where there is little sunlight reaching the plant, the stem moves or leans closer to the light so that the chlorophyll can get some light and that is helpful because sunlight is a necessity in the process of photosynthesis. After the water gets soaked in from the roots, it travels in the xylem up the stem.

Leaves & Cells

The leaves are the part of the plant that collects carbon dioxide through tiny pores called stomata which close automatically when water from the roots begin to dry up. Under a microscope, leaves have a layer of cells called palisade cells. Inside the palisade cells there are small modules called chloroplasts. Within the chloroplasts there is chlorophyll, which is a chemical that gives, plants it’s green colour. Chloroplasts are used to capture light energy from the sun. It is then stored in stacks of thylakoid membranes, which is where photosynthesis takes place. Underneath the layer of palisade cells there are spongy cells which are spaced out for airspaces so there is room for gases like carbon dioxide and water vapour to come in and out of the stomata under the spongy cells. The process in which water evaporates from the leaves and into the air is called transpiration. When the water in the leaves diffuses into the air, more water is sucked up from the xylem tubes, this is called cohesion ‘sticking together’. Adhesion is when water particles stick to other surfaces such as the xylem. These things form a chain of molecules working their way up the xylem due to adhesion and through the plant due to the cohesive chain of water molecules.

Cells in Leaves Diagram

http://www.bbc.co.uk/schools/gcsebitesize/science/images/bi05004.gif

Basic Photosynthesis

Photosynthesis Equation:Carbon Dioxide + Water sunlight—chlorophyll Glucose + Oxygen

http://www.youtube.com/watch?v=mpPwmvtDjWw

Plants in Doha

Qatar is known to be a warm country. A lot of Qatar is desert and even though there is hardly any water in the desert, plants still grow and they adapt to the living conditions of a desert. For example, cactuses are plants that adapt to a desert environment and they do so by spreading their roots so that there is more of a chance of getting water and their wax cuticles tend to be thicker because that way they can store more water and less water can diffuse from the leaves and into the air. Plants can adapt to different living conditions by doing things like this.

Bibliography

Ross, Adam. "Molecular Biology: Osmosis, Concentration Gradient, Plant Cells." AllExperts Questions & Answers. 10 Nov. 2009. Web. 13 Feb. 2011. <http://en.allexperts.com/q/Molecular-Biology-1353/2009/10/Osmosis.htm>.

GerstenfeldTeamS. "YouTube - Adhesion, Cohesion and the Ways Plants Acquire Water." YouTube - Broadcast Yourself. 14 Oct. 2009. Web. 13 Feb. 2011. <http://www.youtube.com/watch?v=kaMDrCgyrfo>.

Mediasematics. "YouTube - Photosynthesis." YouTube - Broadcast Yourself. 13 Dec. 2007. Web. 13 Feb. 2011. <http://www.youtube.com/watch?v=mpPwmvtDjWw>.

"BBC - GCSE Bitesize: Plant Transport." BBC - Homepage. Web. 13 Feb. 2011. <http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway/greenworld/planttransportrev1.shtml>.

"BBC - GCSE Bitesize: Leaves and Photosynthesis." BBC - Homepage. Web. 13 Feb. 2011. <http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway/greenworld/photosynthesisrev1.shtml>.

"BBC - GCSE Bitesize: Photosynthesis." BBC - Homepage. Web. 13 Feb. 2011. <http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/environment/1_food_factory1.shtml>.