Plant nutrition Success criteria Observes the external features

Plant nutrition

Success criteria • Observes the external features of a leaf and make sketches. • Describes the external adaptation of leaves to suit for the process of photosynthesis. • Identifies the importance of plant as the primary producer. • Describes the process of photosynthesis and identifies the raw materials required for photosynthesis.

Success criteria • Investigates to find out that light, chlorophyll and carbon dioxide are necessary for photosynthesis. • Experiments to show that oxygen is released during photosynthesis. • Appreciates plants as environment purifier (uses carbon dioxide and • releases oxygen during day time). • Appreciates the creations of Allah for such blessings.

Primary Producers • Autotrophic nutrition means making their own food. • Plants make their own food with the help of sunlight, water, carbon dioxide and chlorophyll.

photosynthesis • Photosynthesis is a process by which plants prepare their food by using water and carbon dioxide in the presence of chlorophyll and sunlight as a source of energy.

Factors necessary for photosynthesis • Carbon dioxide from the air diffuses into the leaf through stomata. • The water and minerals are absorbed by roots and transported to other parts of the plant through the vessels in stem. • Sunlight provides energy to produce food. • Chloroplasts is the site of photosynthesis. It contain the green coloured pigment chlorophyll which absorb the maximum amount of sunlight.

photosynthesis • The oxygen produced during the reaction is released into the atmosphere through the stomata. • Photosynthesis helps to maintain a balance between oxygen and carbon dioxide in the atmosphere

Leaves and photosynthesis • • Leaves are adapted to perform their functions. For example, they have a large surface area and many chloroplasts to absorb sunlight. • The leaf. • Leaves contain many cells with chloroplasts. Leaves are often broad so that they have a large surface area to absorb sunlight. Broader leaves enable more sunlight to be absorbed.

Parts of the leaves • Petiole: the stalk of the leaf that joins the blade to the stem. • Blade: the main part of the leaf. Green, thin, flattened and expanded part of the leaf veins. • Midrib: the central vein running down the center of the blade. • Veins provide support and conduct water, minerals and prepare food.

External adaptations of a leaf Adaptation Function Large surface area Most leaves are broad and so have a large surface area allowing them to absorb more light. A thin shape means a short distance for carbon dioxide to diffuse in and oxygen to diffuse out easily. Chlorophyll This chemical gives the leaves their green colour and transfers light energy to chemical energy. Veins Networks of veins support the structure of the leaf and transport substances to and from the cells in the leaf. Stomata These are small holes on the underside of the leaf that allow gases to diffuse in and out.

Importance of photosynthesis • Plants give us oxygen plants release oxygen as a by product during photosynthesis, which is used by humans and animals. • Plant give us food most of the food is directly and indirectly from plants. • Plant give us clothes Cells of some plants produce fibres, which can be spun and woven into fabrics. • Plant give us medicines Different parts of the plants used as medicines.

Products of photosynthesis: During photosynthesis, glucose is formed and oxygen is released. The glucose formed is converted into insoluble form as starch and is stored in the leaves, stems roots, etc. The food synthesized by green leaves is transported to other parts of the plant by the stem. The simplest method of testing whether photosynthesis has taken place is to find out if starch is present in a leaf.

What happens to the glucose (sugar) that is made during photosynthesis? • As previously said, glucose(sugar) is made during photosynthesis. • The plant uses it for it’s own life processes. • The phloem transports it through the plant. • Excess glucose is binded together to form starch. • The starch is stored in the plant, mainly by the roots. • Starch in a photosynthesising plant can already be detected in the leaves

Starch test