Photosynthesis

Photosynthesis

• Essentials for growth- sunlight: leaves; water: roots.
• Needs four key minerals- nitrates, phosphates, potassium, magnesium.
• No Nitrates= Poor root growth; yellow leaves ( amino acids)
• No Phosphates= Poor root growth, discoloured leaves (DNA, membranes)
• No Potassium= Poor flower and fruit growth (Photosynthesis, respiration)
• No Magnesium= Yellow leaves (Building Chlorophyll-green)
• Fertilisers = manure + artificial

What is Photosynthesis?

• Animals need to eat food to get their energy. But green plants and algae do not. Instead they make their own food in a process called photosynthesis. Almost all life on earth depends upon this process. Photosynthesis is also important in maintaining the levels of oxygen and carbon dioxide in the atmosphere. Plants need carbon dioxide, water and light (a source of energy) for photosynthesis.
• Plants make glucose and oxygen using photosynthesis. Carbon dioxide + water = glucose + water.
• Photosynthesis takes place inside plant cells in small object called chloroplasts. Chloroplasts contain a green substance called chlorophyll. This absorbs the light energy needed to make photosynthesis happen. Plants and algae can only carry out photosynthesis in the light. Plants get carbon dioxide from the air through their leaves and water from the ground through their roots. Light energy comes from the sun. The oxygen produced is released into the air from the leaves. The glucose produced can be turned into other substances, such as starch and plant oils, which are used as an energy store. This energy can be released by respiration.

Adaptations of the leaf

• Thin- Provides a short distance for carbon dioxide to move by diffusion into the leaf. Contains chlorophyll-absorbs light.
• Stomata- Allows carbon dioxide to move by diffusion into the leaf.
• Guard cells- To open and close the stomata depending on the conditions.
• Network of the tubes(xylem and phloem)- To transport water (xylem) and food (phloem)

Light

• A leaf usually has a large surface area, so that it can absorb a lot of light. Its top surface is protected from water loss, disease and weather damage by a waxy layer. The upper part of the leaf is where the light falls and it contains a type of cell called a palisade cell. This is adapted to absorb a lot of light. It has lots chloroplasts and is shaped like a tall box.

Carbon Dioxide

• Plants get carbon dioxide that they need from the air through their leaves. It moves by diffusion through small holes in the underside of the leaf called stomata. Guards cells control the size of the stomata so that the leaf does not loose too much water in hot, windy or dry conditions.
• The lower part of the leaf is a spongy layer with loose-fitting cells. These let carbon dioxide reach the other cells in the leaf, and also let the oxygen produced in photosynthesis leave the leaf easily.

Water

• The water needed for photosynthesis is absorbed through the roots and transported through the roots and transported through tubes to the leaf. The roots have a type of cell called a root hair cell. These project out for the root into the soil and have a big surface area and thin walls. This lets water pass into them easily. Root cells do not contain chloroplasts as they are normally in the dark and cannot carry out photosynthesis.

Photosynthesis and respiration in plants.

• Plant cells respire just as animal cells do. If they stop respiring they will die.
• aerobic respiration- glucose + oxygen = carbon dioxide +water
• photosynthesis- carbon dioxide + water = glucose + oxygen
• Photosynthesis usually results in a gain of glucose once respiration has been accounted for. Plants that lose their leaves in winter store food produced during the summer by photosynthesis. They store enough food to last them over winter, and to provide energy reserves for new growth in the spring. They are called deciduous plants.
• Dark- Respiration but no photosynthesis oxygen taken in, carbon dioxide given out.
• Dim light- Photosynthesis rate equals respiration rate. Neither gas is taken in or given out.
• Bright light- Photosynthesis's greater than respiration rate. Carbon dioxide rate taken in, oxygen given out.

Water Transport

• Phloem is made of chains of living phloem cells. Carries sugars dissolved in water throughout the plant.
• Xylem is formed from chains of hollow tubes made from dead xylem cells. Carries water up from roots to leaves.
• How does water get in?
• The roots of a plant provide:
• A way of getting water from the soil.
• Stability for the plant by anchoring it into the ground.
• The water absorbed is used for:
• photosynthesis
• keeping the plant rigid
• all the chemical reactions in the plan
• to move dissolved sugars and minerals (e.g. nitrates) to cells
• Plant roots have root hair cells that have two features which help to take in water:
• projection that increases the surface area
• thin cell wall for water to get through easily

Top and Bottom of Leaf

• Chloroplast contains the green pigment chlorophyll which traps light. Photosynthesis is the name of the chemical reaction that changes the carbon dioxide and water into glucose-food for the plant. Chloroplasts are where a plant makes its own food.
• Photosynthesis= Carbon Dioxide+ Water ----chlorophyll---> glucose + oxygen
• stomata roots chloroplast
• ( air)
• Stomata are small holes that are opened and closed by guard cells. The get water when they are open during the day and closed in the night it nothing is able to escape. It closes up in hot weather to prevent evaporation and opens in the cold to get water.

Food Groups

• Carbohydrates for energy
• Proteins for growth and repair
• Fats to store energy
• Vitamins and minerals to keep the body healthy
• The carbohydrate is called glucose- it is a simple sugar that is soluble in water
• C₆H₁₂O₆ - Glucose

More Photosynthesis

• Respiration= glucose + oxygen -> carbon dioxide + water
• ENERGY
• Animals respire in the day and the night
• Plants photosynthesis in the day and respire in day day a little but mostly in the night
• Balanced Symbol Equation For Photosynthesis= 6CO₂ +6H₂O-> C₆H₁₂O₆ + 6O₂

ANIMALS PLANTS BOTH

• Oxygen is taken to the cells in the blood Glucose is made by photosynthesis Respiration releases energy from glucose
• Glucose is obtained in the blood Glucose in made in palisade cells The products of aerobic respiration are CO₂ and water
• Glucose is taken to the cells in the blood Water is carried away in xylem vessels The reactants in aerobic respiration are oxygen + glucose
• Carbon Dioxide is taken away in the blood Cells die if they do not get enough oxygen
• Respiration happens in the cytoplasm of cells
• Respiration happens in the day and night

Plant Reproduction

• Biomass is all the materials in an organism. Made from thousands of different substances. Most substances are made using glucose. Glucose can be converted to other carbohydrates including starch. It can be converted to cellulose and fats. It can be combined with mineral salts to make proteins.Can be used for respiration in every living cell all the time. Glucose can be used for respiration in every living cell all the time. Glucose can be converted to fructose. fructose is also known as "fruit sugar". It can also be converted to sucrose which is found in almost all plants especially sugar can/ beet. Sugar cane = Sugar. However glucose is a soluble sugar. Glucose is converted to starch. 1000s of glucose molecules join together to form long chains- starch. Starch is insoluble so it can be in plants and break down into glucose and other sugars when needed. Glucose can be converted to cellulose. Cellulose fibres are found in plant cell walls. Cellulose is used to make paper. Glucose can be converted into lipids for use in cell membranes and for food storage in seed such as coffee beans, etc. Glucose can be combined with mineral salts such as nitrates which can be found in soil. These combine with glucose to make proteins. Proteins are used for growth and repair, and stored in some seeds. We know the food plants make for photosynthesis are called carbohydrates. Carbs contain the atoms carbon, hydrogen and oxygen. C₆H₁₂O₆
• Sugars= Honey and Nectar| Starch= rice, potatoes and flour| Protein= soya and peanuts| Fats/Oils= corn, olive and veg oil|Cellulose= paper, cotton and card