V.C.E. Biology Unit 1 Heterotrophs are consumers

Nutritional Requirements Carbohydrates – an immediate source of energy and can be used to store energy as glycogen. Carbohydrates – an immediate source of energy and can be used to store energy as glycogen. Lipids – also an energy source and store (adipose cells) important for membranes, hormones and vitamins. Lipids – also an energy source and store (adipose cells) important for membranes, hormones and vitamins. Proteins – cells need amino acids to make proteins. There are nine essential amino acids that must be in an animals diet. Proteins – cells need amino acids to make proteins. There are nine essential amino acids that must be in an animals diet. Vitamins – vitamins are a diverse group of organic compounds which are used in a broad range of chemical processes in the cell. Vitamins – vitamins are a diverse group of organic compounds which are used in a broad range of chemical processes in the cell. Minerals – these are the mineral salts or metal salts that are important for making new cells, particularly blood cells and to aid other processes. Minerals – these are the mineral salts or metal salts that are important for making new cells, particularly blood cells and to aid other processes.

Digestion Food must be digested by heterotrophs. Chemical digestion is the use of chemicals called enzymes to break large molecules into smaller ones for absorption into the blood vessels Chemical digestion is the use of chemicals called enzymes to break large molecules into smaller ones for absorption into the blood vessels Physical digestion is the use of teeth, specialised bones, tongue and muscles to mechanically break down large chunks of food into smaller chunks – increasing the surface area to volume ration for the enzymes to work. Physical digestion is the use of teeth, specialised bones, tongue and muscles to mechanically break down large chunks of food into smaller chunks – increasing the surface area to volume ration for the enzymes to work.

Digestive Systems The simplest heterotrophs absorb their nutrients from their surroundings by diffusion. The simplest heterotrophs absorb their nutrients from their surroundings by diffusion. As organisms become more complex they need to eat food, digest it and send the chemicals around the body for each cell to use. Therefore systems of specialised organs evolved. Each system suits the organisms diet. As organisms become more complex they need to eat food, digest it and send the chemicals around the body for each cell to use. Therefore systems of specialised organs evolved. Each system suits the organisms diet. Systems contain features for mechanical digestion, a one way flow, sequential release of enzymes, improved surface areas for uptake of nutrients and efficient excretion of wastes. Systems contain features for mechanical digestion, a one way flow, sequential release of enzymes, improved surface areas for uptake of nutrients and efficient excretion of wastes.

Mammalian Digestive Systems There is much variation between mammals, however, they all contain: There is much variation between mammals, however, they all contain: A mouth cavity (may have teeth and tongue) – initial physical and chemical digestion (uptake of glucose) Oesphagus – physical digestion Stomach – physical digestion and chemical digestion (break down of fats and proteins) Small Intestine (villi and microvilli) – chemical digestion – major site of absorption of lipids, proteins and carbohydrates Large Intestine – final chemical digestion (salts absorbed) and uptake of water Rectum – excretes waste material.

Energy Storage All animals will feast when food is plentiful and store the excess energy for times of famine as this is a natural cycle. All animals will feast when food is plentiful and store the excess energy for times of famine as this is a natural cycle. Humans have broken free of this cycle and need to be sure that they do not regularly eat more energy than they are using or they will store excess energy – which may cause medical concerns. Humans have broken free of this cycle and need to be sure that they do not regularly eat more energy than they are using or they will store excess energy – which may cause medical concerns. Animals store excess energy as fat because it is lighter than carbohydrates (50%), contains more ATP (25%) and can therefore yield more energy for the animal. Animals store excess energy as fat because it is lighter than carbohydrates (50%), contains more ATP (25%) and can therefore yield more energy for the animal. Excess energy is initially stored in the liver and high energy use areas as glycogen (cho), but if there is more excess then lipids are deposited in adipose tissue around organs and about the body. Excess energy is initially stored in the liver and high energy use areas as glycogen (cho), but if there is more excess then lipids are deposited in adipose tissue around organs and about the body.