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WJEC BY2.5 Adaptations for Nutrition

Nutrition is the process by which organisms obtain energy to maintain life functions and matter to create
and maintain structure. These are obtained from nutrients.

Autotrophic organisms such as green plants use the simple organic materials carbon dioxide and water
to manufacture energy -containing complex…

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Fungi are made up from tiny threads called HYPHAE ­ enzymes are secreted from the tips

Human digestion

Humans, like all animals, use holozoic nutrition, which consists of these stages:

o Ingestion- taking large pieces of food into the body through the mouth

o Digestion- breaking down large insoluble food…

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Humans are omnivores, they eat both plant and animal material. The teeth are not particularly
specialised but having four different types of teeth to carry out different functions reflects a
mixed diet. In total humans have 32 teeth and these are made up of:

o Eight chisel -shaped incisors at…

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Dentition in carnivores

Carnivorous mammals, such as a tiger, have teeth adapted for catching and killing prey, cutting
or crushing bones and for tearing meat.

The sharp incisors grip and tear flesh from bone. The canine teeth are large, curved and
pointed for seizing prey, for killing and also tearing…

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In humans the site of ingestion/digestion/absorption is the gut which is a long tube that extends from
the mouth to the anus together with a number of associated glands

In simple organisms, feeding on only one type of food the gut is undifferentiated, however in more
advanced organisms the digestive…

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Muscle layer - is made of smooth muscle, under involuntary control is subdivided into inner circular
muscle (which squeezes the gut when it contracts) and outer longitudinal muscle (which shortens
the gut when it contracts).

Serosa - a tough layer of connective tissue that holds the gut together, and attaches…

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Amylase Maltase

Starch Maltose

Protein ­ digestion takes part in 2 stages

Endopeptidase Exopeptidase

Protein Polypeptide Amino Acids

Endopeptidases hydrolyse peptide bonds along the length of the amino acid chain to provide more
`free ends' for exopeptidases to act on

These are NOT polymers!

Bile Lipase

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Enzyme/chemical Site of Site of action Substrate Product
Amylase Salivary glands Mouth
Starch Maltose
Pancreas Duodenum
Endopeptidase Gastric glands Stomach
Protein Polypeptides
Pancreas Duodenum
Exopeptidase Epithelial cells at Ileum Polypeptides Amino Acids
tips of villi
Maltase Epithelial cells at Ileum Maltose Glucose
tips of villi
Lipase Pancreas Duodenum Lipid…

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The duodenum makes up the first 20cm of the small intestine and receives secretions from both the
liver and the pancreas

Bile salts are produced in the liver and stored in the gall bladder from where it passes into the
duodenum via the bile duct. It contains no enzymes but…

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Mechanisms for Absorption


Glucose is absorbed by diffusion and active transport into capillaries and then travel via the
hepatic portal vein to the liver
Glucose is absorbed from the blood by cells, for energy release in respiration, and any excess is
converted to fat for storage


Amino acids…




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