(for test)

What we need to know:

• Photosynthesis word and chemical equation

• What is Chlorophyll and what is it used for

• What are the uses of Carbohydrates in plants

• External and Internal structure of a Leaf

• Which factors affect the rate of photosynthesis and why

• What is a Diet

• What are the 7 types of nutrients present in a balanced diet

• What is the function of each of these nutrients

• Structure of the Digestive system

• Function of each section of the Digestive system

• The different stages of digestions (Ingestion, Digestion, Absorption, Assimilation and Egestion)

• Difference between Physical and Chemical digestions and where do these take place

• What Enzymes are produced by the Digestive system and where

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Photosynthesis - Process by which plants synthesis carbohydrates from raw materials using energy from sunlight (and chlorophyll). It converts sunlight energy into chemical energy that living organisms can store and use.

• Water + Carbon Dioxide = Glucose + Oxygen

• 6H₂O + 6CO₂→ C₆H₁₂O₆ + 6O₂

Chlorophyll - Green pigment which is present in chloroplasts and responsible for the absorption of light, It transferses the light into chemical energy to make carbohydrates. (It is present in the leaves).

Uses of Carbohydrates in plants -

• Energy for respiration

• Storing to use later

• Sucrose for transport

• Making cell wall

• Making nectar to attracts pallinators

• Making amino-acids to produce proteins

• Making chlorophyll

External structure of a leaf -

• Midrib

• Vein

• Lamina

• Cross-section of vein

• Transverse section of leaf

Vascular bundles - Collections of xylem tubes and phloem vessels running side by side, which form the veins in a leaf.

Internal structure of a leaf (functions) -

Cuticle - Waxy substance which forms a thin, transparent and waterproofing covering layer.

Upper and Lower epidermis - Protective barrier around the leaf to prevent pathogens entering and causing harm to the organisms. Epidermis cells are transparent to let light pass through (to the palisade cells).

Palisade layer - Tall, narrow cells containing very large numbers of chloroplasts. That is where most photosynthesis take place.

Spongy layer - Have many air spaces between them that allow Carbon Dioxide and oxygen to diffuse. The spaces also allow vapour to move from the surface of the cells to the outside of the leaf. (They can also make photosynthesis).

Guard cells - Cells that surround the stomata and change shape depending on the volume of water. They control the rate of transpiration by becoming turgid or flaccid, opening or closing stomata.

Stomata - Small holes found on the surface of a plant that can be opened or closed by guard cells to control water loss and gas exchange.

Factors affecting the rate of Photosynthesis -

• Supply of raw materials : carbon dioxide and water

• Quantity of sunlight, which provides energy for reactions

• Temperature, affects the activity of enzymes

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Diet - The food eaten in one day.

Balanced diet - Diet containing all of the required nutrients in suitable proportions and the right amount.

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The 7 Nutrients -

• Carbohydrates

• Proteins

• Minerals

• Fats

• Vitamins

• Water

• Fibre

Functions of the Nutrients -

Carbohydrates - Used as source of energy in respiration in cells.

Fats - Insulation, energy, waterproofing, structure, and protection around delicate organs.

Protein - Broken down into amino-acids in digestion and absorbed into the blood. Used to produce new proteins by protein synthesis, where they are used as enzymes in reactions and for structure. They can also be used for signalling as hormones and carrying other molecules.

Vitamins ( C and D ) - Vitamin C Is used in the synthesis of proteins which help make up the skin, ligaments and blood vessels, and repairing tissues. Vitamin D helps the uptake of calcium during digestion and is also a factor in maintaining healthy bones.

Minerals ( Calcium and Iron ) - Calcium is needed for healthy bones and teeth. It also has a role in blood clotting. Iron is present in haemoglobin, it transfers oxygen around the body in the blood for cells to use in respiration.

Fibre - Helps food to move through the stomach and intestines, prevents constipation, it also adds bulk.

Water - Acts as solvent in which chemical reactions occur. It also helps to maintain a constant temperature in the body due to its high specific heat capacity and is a metabolite.

Functions of the Digestive system -

Salivary glands - Group of cells close to the mouth, which secrete saliva (mixture of water, mucus and amylase) into the salivary ducts.

Oesophagus - Allows food to pass from the mouth into the stomach by peristalsis.

Stomach - Has strong muscular walls that contract and relax to mix food with enzymes and mucus (chemical digestion). The stomach walls also contain cells which produce enzymes (and others) which make hydrochloric acid. the hydrochloric acid has a low pH level that kills harmful microorganisms from the food.

Duodenum- First part of the small intestine, into which the pancreatic duct and bile duct empty fluids.

Small Intestine - Part of the alimentary canal between the stomach and the colon. It is long, narrow and is about 5 meters long. The acidity from the stomach is neutralised and protease, lipase and amylase enzymes are secreted to break down molecules. consists of the duodenum and ileum.

Ileum- Second part of the small intestine where most absorptions take place.

Pancreas - creamy-white colored gland lying underneath the stomach. Pancreas makes pancreatic juice containing protease, lipase and amylase enzymes, that flow through the pancreatic duct into the duodenum where chemical digestion will take place.

Liver - Large, dark-red organ that carries out many functions including production of bile (yellowish-green alkaline that neutralises acid from the stomach) and the regulation of blood glucose concentration.

Gall bladder - Small organ that stores bile (produced by the liver, helps with fat digestion) before it is released into the duodenum.

Colon- First part of the large intestine, that absorbs most of the water that still remains in the food.

Large intestine - Wide part of the alimentary canal consisting of the colon and rectum.

Rectum - Second part of the large intestine that stores undigested food as faeces.

Anus - Exit from the alimentary system through which faeces are removed.

Different stages of Digestions -

Ingestion - Taking food into the mouth using lips, teeth and tongue.

Digestion - Large pieces are broken down into small pieces (mechanical digestion), large molecules are broken down into small molecules (chemical digestion).

Absorption - Movement of the small nutrient molecules and mineral ions through the walls of the intestines and into the blood.

Assimilation - Nutrients are being absorbed by individual cells and used for energy or to make new substances.

Egestion - Materials in our food that we cannot digest (mostly fibre) remains in the intestines and eventually passes out as faeces.

Difference between Physical (mechanical) and Chemical digestions -

Physical Digestion - Type of digestion that involves physically breaking down food into smaller pieces. Mostly done by the teeth in the mouth, but also in the stomach. it increases the surface area for chemical digestion.

Chemical Digestion - Type of digestion that involves breaking down large, insoluble molecules into smaller, soluble molecules by being catalysed by enzymes so they can be absorbed into the body. Chemical digestion starts in the mouth by the saliva, and continues throught the small intestine.

Enzymes produced by the digestive system -

Amylase - Secreted by the salivary glands and the pancreas, and Acts in the mouth and duodenum. (It breaks down starch to simpler sugars).

Protease - Secreted by the walls of the stomach and the pancreas, and Acts in the stomach and the duodenum. (It breaks down protein to amino-acids).

Lipase - Secreted by the pancreas, and Acts in the duodenum. (It breaks down fats to fatty acids and glycerol).