What is digestion?
By biological means involves both mechanical and chemical processes to break up food into smaller parts that can be absorbed by the body.
Give the importance of decomposers and a few examples of them.
Decomposers are important as they break down dead matter. They acquire energy from the dead organic matter and keep the world community alive by breaking down dead organisms and releasing minerals.
Examples of decomposers are saprophytes, saprophytic bacteria and fungi.
Where are paramecium’s found and what is its mode of locomotion?
They are found in fresh waters and their mode of locomotion is beating of the cilia that covers their cell membranes.
What do paramecium’s feed on?
Bacteria that float in the water, Cytosome .
What are the feeding steps of a paramecium? (5)
- it uses its cilia to beat food particles in the surrounding water down the oral groove.
- Food vacuoles surround the food accumulating at the end of the cytopharynx.
- Lysosome containing enzyme fuses with the food vacuoles to digest the food.
- The digested food diffuses through the cell cytoplasm and mitochondria oxidizes it for ATP.
- Wastes are egested by exocytosis at the cell membrane.
Why cannot protists survive with external digestion?
Because they are motile, their energy needs are too great to stay in one place and wait for their enzymes to digest food.
What type of digestive system do cnidarians have?
Sac-like gut with only one opening and one unspecialised chamber.
What are a cnidarians feeding steps? (3)
- food is trapped and pushed into their mouth with tentacles.
- Food is digested and absorbed in the one gut chamber.(gastrovascular cavity)
- Waste is ejected back and out of the mouth.
State 2 adaptive values of sac- like gut system.
- Food is ingested and egested from the same opening.
- Since they have only one gut opening, it needs to completely digest and absorb a meal and egest wastes before it can eat anything else.
What type of digestive system do annelids have?
Simple tube-like gut system
Why is a annelids digestive system more efficient than cnidarians?
Because annelids have 2 gut openings, unlike cnidarians that only have 1.
Explain the feeding steps of a earthworm.(7 )
- The earthworm sucks in soil through their mouth using the muscular pharynx.
- The oesophagus then moves the soil by peristalsis to the crop.
3.The crop stores the food until there is room for it in the gizzard. - The muscular gizzard then grinds up the food.
- Then it moves to the intestine where the intestine both digest and absorb the bits of organic material contained in the soil.
- The inorganic portion of the soil and any indigestible materials it contains are egested through the anus.
- Blood absorbs the digested food from the small intestine and carries it to the body cells.
Describe a typhlosole and state its function?
Is a long ridge that hangs down into a worms intestine to increase surface area for nutrient absorption.
State a few specialised chambers a earthworm has?
the crop, gizzard, muscular pharynx and the intestine.
State an adaptive value of specialised chambers.
-Having specialised chambers allows several functions to proceed at the same time in different parts of the body.
- The organism can eat while the earlier meal is digesting as the food moves through the gut in one direction.
What type of gut system do arthropods have?
Complex tube-like gut.
Explain the feeding steps of a cockroach.
- It cuts its food with mouthparts called mandibles and holds its food with maxillae. The saliva from the salivary glands moisten the food.
- The crop stores the food and the gizzard grinds it.
- The caecum secrets a digestive enzyme into the mid-gut. The mid-gut digests and absorbs food.
- The hind-gut absorbs water from the faeces.
- Indigestible food is egested out through the anus.
- The blood absorbs digested food from the mid-gut and carries it to the body cells.
Name 2 intestinal parasites.
Helminths- hookworms, flatworms, round worms, tapeworms.
Protozoa - single-celled animal that cannot survive in the absence of water. example, giardia.
How do intestinal parasites obtain their food?
Since the food is already digested in the host’s small intestine, the parasites directly absorb the digested food from the host’s intestine. All they need to do is hold on and reproduce, therefore they only have organs for attachment and reproduction.
What are some ways parasites can get entry to your intestine?
Through the mouth from uncooked or unwashed food, contaminated water or hands, or by the skin contact with larva in infected soil.
Name the type of beaks these birds have? and for what.
-Hawks
-Herons
- Honeyeaters
- Parrots
Hawks- sharp hooked beaks for tearing prey.
Herons- long pointy beaks for ‘fishing’
Honeyeaters- long curved beaks for sucking flower nectar.
Parrots- short strong beaks for cracking seeds.
Explain why birds don’t have teeth and what adaptive feature they have instead.
Teeth are too heavy and will add to the weight instead they have muscular gizzards for grinding up food. They also have crop for food storage.
Why do some birds eat small stones?
To help their gizzard grind up the food.
Explain the feeding steps of a bird.
1.The food moves in through the mouth.
2.oesophagus then transports the food from the mouth to the stomach.
3. The proventriculus stores the food and the gizzard uses grit to grind grains and fibres into smaller particles.
4. Then the food moves to the small intestine for digestion and nutrition absorption.
5. The bacterial action then breaks down undigested food passing through the intestine.
6. The large intestine then absorbs water and dries out indigestible food and eliminate waste products.
7. The food then finally leaves the body through the vent.
