Digestion

Question 1

What is digestion?

Answer 1

By biological means involves both mechanical and chemical processes to break up food into smaller parts that can be absorbed by the body.

Question 2

Give the importance of decomposers and a few examples of them.

Answer 2

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.

Question 3

Where are paramecium’s found and what is its mode of locomotion?

Answer 3

They are found in fresh waters and their mode of locomotion is beating of the cilia that covers their cell membranes.

Question 4

What do paramecium’s feed on?

Answer 4

Bacteria that float in the water, Cytosome .

Question 5

What are the feeding steps of a paramecium? (5)

Answer 5

1. it uses its cilia to beat food particles in the surrounding water down the oral groove.
2. Food vacuoles surround the food accumulating at the end of the cytopharynx.
3. Lysosome containing enzyme fuses with the food vacuoles to digest the food.
4. The digested food diffuses through the cell cytoplasm and mitochondria oxidizes it for ATP.
5. Wastes are egested by exocytosis at the cell membrane.

Question 6

Why cannot protists survive with external digestion?

Answer 6

Because they are motile, their energy needs are too great to stay in one place and wait for their enzymes to digest food.

Question 7

What type of digestive system do cnidarians have?

Answer 7

Sac-like gut with only one opening and one unspecialised chamber.

Question 8

What are a cnidarians feeding steps? (3)

Answer 8

1. food is trapped and pushed into their mouth with tentacles.
2. Food is digested and absorbed in the one gut chamber.(gastrovascular cavity)
3. Waste is ejected back and out of the mouth.

Question 9

State 2 adaptive values of sac- like gut system.

Answer 9

• 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.

Question 10

What type of digestive system do annelids have?

Answer 10

Simple tube-like gut system

Question 11

Why is a annelids digestive system more efficient than cnidarians?

Answer 11

Because annelids have 2 gut openings, unlike cnidarians that only have 1.

Question 12

Explain the feeding steps of a earthworm.(7 )

Answer 12

1. The earthworm sucks in soil through their mouth using the muscular pharynx.
2. 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.
3. The muscular gizzard then grinds up the food.
4. Then it moves to the intestine where the intestine both digest and absorb the bits of organic material contained in the soil.
5. The inorganic portion of the soil and any indigestible materials it contains are egested through the anus.
6. Blood absorbs the digested food from the small intestine and carries it to the body cells.

Question 13

Describe a typhlosole and state its function?

Answer 13

Is a long ridge that hangs down into a worms intestine to increase surface area for nutrient absorption.

Question 14

State a few specialised chambers a earthworm has?

Answer 14

the crop, gizzard, muscular pharynx and the intestine.

Question 15

State an adaptive value of specialised chambers.

Answer 15

-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.

Question 16

What type of gut system do arthropods have?

Answer 16

Complex tube-like gut.

Question 17

Explain the feeding steps of a cockroach.

Answer 17

1. It cuts its food with mouthparts called mandibles and holds its food with maxillae. The saliva from the salivary glands moisten the food.
2. The crop stores the food and the gizzard grinds it.
3. The caecum secrets a digestive enzyme into the mid-gut. The mid-gut digests and absorbs food.
4. The hind-gut absorbs water from the faeces.
5. Indigestible food is egested out through the anus.
6. The blood absorbs digested food from the mid-gut and carries it to the body cells.

Question 18

Name 2 intestinal parasites.

Answer 18

Helminths- hookworms, flatworms, round worms, tapeworms.
Protozoa - single-celled animal that cannot survive in the absence of water. example, giardia.

Question 19

How do intestinal parasites obtain their food?

Answer 19

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.

Question 20

What are some ways parasites can get entry to your intestine?

Answer 20

Through the mouth from uncooked or unwashed food, contaminated water or hands, or by the skin contact with larva in infected soil.

Question 21

Name the type of beaks these birds have? and for what.
-Hawks
-Herons
- Honeyeaters
- Parrots

Answer 21

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.

Question 22

Explain why birds don’t have teeth and what adaptive feature they have instead.

Answer 22

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.

Question 23

Why do some birds eat small stones?

Answer 23

To help their gizzard grind up the food.

Question 24

Explain the feeding steps of a bird.

Answer 24

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.

Question 25

What is cloaca in a bird?

Answer 25

Where the digestive, urinary and reproductive systems meet.

Question 26

What does liver in a bird aid in?

Answer 26

It aids in the metabolism of carbohydrates, fats and proteins.

Question 27

Why cannot humans digest plants? and what would happen if we ate them?

Answer 27

We cannot digest plants as plant cells have very tough cell walls made of cellulose. The human digestive system lack enzymes that are needed to digest cellulose thus if consumed, it would just pass through the alimentary canal and out of the anus.

Question 28

What class of animals do cattle’s belong to?

Answer 28

Ruminants.

Question 29

Why are cows known to be a good example of ‘masticators’?

Answer 29

Due to the double chewing in cows.

Question 30

What food do cows not handle well?

Answer 30

all grains and high fat diets.

Question 31

What are some adaptations herbivorous animals have for digesting plants.

Answer 31

-Wide flat teeth for grinding leaves between their teeth.
- Double chewing, they chew the material, swallow it and then regurgitate it to chew it again later.
- Symbiotic bacteria, is a cellulose- digesting bacteria that is live in their guts and breaks down cellulose in cell walls. In return, the herbivore provides the bacteria with food.
- They have very long intestine to allow herbivores more time to digest and absorb food.

Question 32

State the type of teeth humans have for:
- Tearing flesh
-for grinding food

Answer 32

• sharp canine teeth
• flat molar teeth

Question 33

Differentiate between external digestion and internal digestion.

Answer 33

External digestion is where food is digested from the outside of an organisms body through secreting enzymes that degrade food material and then absorbed through diffusion whereas internal digestion happens inside ones body.

Question 34

What are some organisms that use external digestion?

Answer 34

Cnidarians and some bacteria.

Question 35

Explain how do external digestions occur?

Answer 35

The organism secretes digestive enzymes onto the dead matter and then wait for the enzymes to decompose the food which is then absorbed into their cells using active transport. (diffusion)

Question 36

Why is external digestion not suitable for mobile organisms?

Answer 36

It requires the organism to stay with its food until it has completed digestion and absorption.

Question 37

How is external digestion beneficial to immobile organisms?

Answer 37

They save their energy expenses of taking in larger molecules and having digestive organs.