Mammal as a Consumer


Demonstrate understanding of biological ideas relating to a mammal(s) as a consumer(s)

Introduction to the topic

This assessment is about Mammals and how they consume resources such as food, oxygen and water to stay alive. To begin with this topic it is important to know what a mammal is.

The following link gives you a good introduction to what a mammal is. Watch the video below and play the game Mammal Maker.

Here is an excellent powerpoint for the topic from Mrs Loughnane Click here

A mammal is an animal, what does this mean?

An animal is:

  • a multicellular organism - made of many cells
  • It is heterotrophic, which means it feeds on other plants and/or animals
  • capable of moving
  • respond to factors or stimuli in their environment, such as temperature, light

A mammal has:

  • Vertebrate – has a backbone
  • has four chambered heart
  • Has lungs for gas exchange
  • homoeothermic - warm blooded
  • Has fur and/or hair
  • mammary glands - to feed young by producing milk

The main groups are:

Monotremes - lays eggs, eg, echidna and platypus.

  • Marsupials - pouches, eg, kangaroo, possum, koala
  • Placental - placenta attaches embryo to uterus by umbilical cord, eg, cat, dog, lion, human, rat!

Life processes - an introduction

A mammal needs energy to survive. ›Energy is used for growth, reproduction, excretion, movement, respiration, cell division, sensitivity and active transport of substances across the membranes of cells. TO make useful energy the cells undergo respiration. Respiration later down the page will go into more detail but the basic respiration idea is that cells need food, oxygen and waste removed. Cells are tiny, so nutrients must be tiny to get across the cell membrane. ›This is why food must be digested – to make food particles small and soluble.

Before we start have a look at the following link.

Inner body website - A good place to start to see where all the systems are placed in the body. Link here

Digestive System

Some animations to help you understand the basics

Intro to the digestive system

A really good introduction

Make a digestive system

Another good animation

The organ system which breaks down food (into smaller pieces), so that the body can use it/ can be absorbed into the blood

The main types of food can be broken into the following simpler parts

Carbohydrates, ›Lipids and ›Proteins

These can be broken down into:

  • Proteins into amino acids
  • Carbohydrates into soluble single sugars
  • Lipids to soluble fatty acids and glycerol

The main steps of this are:

1. Ingestion – food taken in the mouth.

2. Digestion – physical and chemical (enzymes) breaking down of food.

  • Physical digestion occurs when food is broken down into smaller pieces by the teeth or the muscle action of the stomach wall.
  • This increases the surface area available for the enzymes in chemical digestion to work on which increases the overall efficiency of the digestive process.
  • This breaks proteins into soluble amino acids, carbohydrates into soluble single sugars such as glucose, lipids to soluble fatty acids and glycerol.
  • The cells use these for energy and growth.

The teeth are used during this step

The science learning hub has a good section on digestion - check it out.


Herbivores and carnivores have both similarities and differences in their teeth.

Herbivores and carnivores both have teeth in their mouths involved in physical digestion.

  • They both have three types of teeth, incisors, canines and molars.
  • The teeth play a major role in physical digestion of food.
  • The teeth are firmly anchored into sockets of the jawbone and they consist of the same basic parts of enamel, dentine, pulp and cement.
  • However, their shape, structure, number and position vary, depending on what the mammals diet mainly consists of.

Why are teeth important?

  • The teeth allow the mammals to extract energy from the food they consume in order for them to survive and not develop a deficiency disease. Herbivores need to break down the tough cellulose cell wall of the plant to access the available energy. Their modified molars and jaw allows them to do this.
  • Carnivores on the other hand need to be able to catch, kill, tear, and rip flesh off other animals. Thus they need teeth that can tear and rip at flesh so they can access energy stored in the food to carry out life processes.

3. Absorption – small soluble food particles pass from gut into capillaries.

4. Assimilation – small soluble food molecules enter cells and used for growth, repair and cellular respiration.

5. Egestion – undigested food such as plant fibre leaves the anus as faeces.

More on this can be found lower on the page.

Click on the picture below.

Respiratory System

The organ system which exchanges gases with the environment structural components involved with the life processes

How is it used in cells?

The alimentary canal from mouth to anus

the heart, veins, arteries, and capillaries

Circulatory system

The organ system that transports material in blood such as food or oxygen to every cell in the body and removes waste such as carbon dioxide

Blood transports various substances from one part of the body to another by continuous flowing through a closed system of blood vessels known as the circulatory system. The blood flow is known as blood circulation. Blood is moving by means of an organ known as the heart, which is a muscular pump that draws blood in when it relaxes and pushes it out at great force when it contracts.

Blood vessels are responsible for the transportation of blood from the heart around the body and vice versa. This intricate network includes:

1. arteries

2. veins

3. capillaries

1. Arteries

They carry the blood away from the heart.

2. Veins

On the other hand, veins convey blood towards the heart.

3. Capillaries

The microscopic thin-walled blood vessels which carry blood from a small artery to a small vein.

There are three distinct parts of the circulatory system:

1. Pulmonary System

2. Coronary System

3. Systemic System

1. Pulmonary Circulation

It is the movement of blood from the heart to the lungs and back to the heart again. The veins bring waste-rich blood excreted from bodily processes such as cellular respiration to the heart. It enters the right atrium through two large veins - the superior vena cava (common anterior) and the inferior vena cava (posterior).

Deoxygenated blood from the upper body, the head, neck and arms is returned to the right atrium by means of the superior vena cava. Deoxygenated blood from the rest of the body is brought back by the inferior vena cava. When the right ventricle is filled with deoxygenated blood, it contracts, pushing the blood through a one-way valve into the right ventricle. This valve is known as the tricuspid valve, consisting of three muscular flaps. These flaps are attached to the wall by muscle tendons called chordae tendineae. These flaps point downwards hence allowing only a uni-directional flow of the blood downwards from the atrium to the ventricle. When the right ventricle contracts, pressure from the blood closes the flaps. This prevents a backflow of blood back into the atrium. The flaps are prevented from being reverted in the opposite direction by the chordae tendineae when the right ventricle contracts. The blood now leaves the right ventricle by the pulmonary arch.

Through this, the blood leaves the heart and divides into the two pulmonary arteries, each leading to one lung. In the lung capillaries, the exchange of carbon dioxide and oxygen takes place.

Oxygenated blood from the lungs is brought back by way of the pulmonary veins re-entering through the left atrium. The oxygen-rich blood passes through a one-way valve known as the bicuspid or mitral valve. It is similar to the tricuspid valve except for the fact that it has two flaps instead of three. When the left ventricle contracts, it will exit the heart through the aortic arch. The aortic arch is a U-shaped tube curved upwards. Semi-lunar valves prevent backflow of blood back to the left ventricle. Blood enters the aortic arch at high pressure, hence giving it enough force to circulate around the body and pushing streams of blood in front.

The right ventricle has considerably thinner walls than the left ventricle this gives the blood sufficient time for the diffusion of gases (gaseous exchange) that occurs in the lungs.

The functioning of the structural components

compare the generalised digestive systems of herbivores, omnivores, and carnivores


Herbivores consume algae or plant matter such as seeds, leaves, and fruits. Because some of these materials are low in easily accessible energy, herbivores have evolved two alternatives for releasing the nutrients: foregut and hindgut gastric fermentation. Gastric fermentation utilizes bacteria that breakdown the hard to digest cellulose, the plant cell wall’s primary component.

In animals that use foregut (a.k.a. pre-gastric) fermentation, the stomach is modified into four chambers/compartments where the first chamber is the rumen. This rumen provides a place for the bacterial breakdown of food. Ruminants regurgitate the partially digested mass from their rumen, known as “cud,” and continue to chew the plant matter to break it down further. Examples of foregut ruminants include cows, sheep, camels, and deer. Camels are known to “spit” when angry, but in actuality, they projectile vomit their cud.In those animals that utilize hindgut fermentation (a.k.a. post-gastric) such as rabbits, rhinos, and horses, the microbial digestion occurs in the large intestine (colon) and/or alarge cecum. These organisms are known as monogastric animals, because they lack the multi-chambered stomachs of the ruminants. The post-gastric fermentation processis less efficient (20% – 65% fiber digestion) than pre-gastric fermentation (52% - 80%);therefore, some monogastric animals practice coprophagy (the consumption of feces) to increase the absorption from nutrients of the food that has already passed through their system. Because this process is not efficient, monogastric herbivores have to consume large amounts of food to meet their nutritional needs, sometimes spending up to 16 hours per day grazing.


Carnivores consume other organisms. Because meat is easily digested compared to plant material, the digestive system of a carnivore is typically shorter than an herbivore of comparable size. In carnivores, the caecum is sometimes reduced and may bepartially replaced by the appendix. Because meat is so easily digested, carnivores and omnivores have lost the ability to synthesize some amino acids. These amino acids, building blocks of proteins, which cannot be synthesized, are known as “essential” amino acids. True carnivores lack enzymes in their saliva to help them digest food. They cannot “chew” by moving their jaws side to side but instead rip the meat into smaller pieces when possible and swallow their food quickly. When the food reaches the stomach, digestive enzymes in the stomach begin to break down the food into absorbable units. The food then moves to the small intestine where most of the absorption occurs and then through the large intestine where waste is eliminated.


Omnivores consume both plant and animal matter. The length of their digestive system more closely resembles that of an herbivore as compared to a carnivore. However, omnivores lack the fermenting vats found in herbivores. Examples of omnivores include humans, pigs, and bears.

The overall function of the life processes

relate processing of food, circulation, and respiration to each other

Digestive System – breaks down food into small particles that can be absorbed into blood stream

• Respiratory System – gets oxygen into the body and removes carbon dioxide

• Circulatory System – transports the nutrients, oxygen, carbon dioxide and other wastes to and from the cells

Digestion produces glucose which moves into the blood and is transported by the circulatory system to the cells.

Oxygen is breathed in and moves into the blood in the lungs and is then transported by the circulatory system to the cells.

Respiration is the converting of glucose and oxygen into energy.

This energy is needed to support life processes and thus the overall survival of the mammal.

The blood in the circulatory system takes glucose from the digestive system and oxygen from the respiratory system to all cells that require energy, so that they have the resources to carry out cellular respiration (the converting of glucose and oxygen into energy).

This energy is needed to support life processes and thus the overall survival of the mammal.

relate processing of food, circulation, and respiration to the overall survival of the mammal

Life processes related to a mammal(s) as a consumer(s) will be selected from

Processing food

There are five steps in the process of nutrition in animals.

1. Ingestion: The process of taking food into the body is called ingestion.

2. Digestion: the process in which the food containing large, insoluble molecules is broken down into small, water soluble molecules is called digestion.

3. Absorption: The process in which the digested food passes through the intestinal wall into blood stream is called absorption.

4. Assimilation: The process in which the absorbed food is taken in by the body cells and used for energy, growth and repair is called assimilation.

5. Egestion: The process in which the undigested food is removed from the body is called egestion.

Physical digestion — teeth and stomach

Herbivore teeth are usually broad and flat and are used to grind plant matter. The lower

incisors and canines are modified for biting off vegetation, and herbivores often lack upper incisors and canine.

Generally, carnivores have pointed incisors and canines designed for killing prey and

ripping muscle. The premolars and molars are designed to crush food.

Omnivore dentition is relatively unspecialized as compared to herbivores and

carnivores. They contain teeth designed for biting (incisors), tearing (canines), grinding

(premolars), and crushing (molars).

chemical digestion

Animation covering the basics of chemical digestion


Digestive enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body.

›Food must be fully digested by the digestive enzymes. Enzymes work most efficiently on small pieces of food with large surface areas. Small pieces of food also move more easily through the digestive system and are less likely to cause blockages.

A great powerpoint from learning on the loop here.

A good link covering enzymes.

Here is an excellent link to no brain too small's sheet on enzymes, print it out.

  • Enzymes are proteins that speed up or catalyse chemical reactions in living things.
  • ›Digestive enzymes are secreted by various organs of the digestive system to chemically digest food particles into smaller particles.
  • ›They are specific for a particular reaction
  • ›They have optimal pH requirements.
  • ›They are affected by temperature – many having a optimal temp of 37⁰C.

Basic practical work relating to digestive enzymes

A good animation

Chemical digestion in the Mouth

When food is taken into the mouth the salivary glands found in the cheeks and under the tongue release saliva which is mixed with the food as it is chewed.› The pH of saliva is around neutral, pH 6.4 to 7.4. Saliva contains an enzyme called amylase. ›Amylase breaks down starch (a long chain of glucose molecules) into glucose. ›Saliva also contains mucin, a slimy substance that moistens and softens food.

the effect of changing pH levels on the enzyme action

Digestion in the stomach

›Physical and chemical digestion occurs in the stomach.

›Physical digestion – thick muscular walls of the stomach are constantly contracting to mix the food with the gastric juices to produce chyme.

›Stomach pH is very acidic pH 1 to 2. The acid is produced by cells in the stomach wall. It kills bacteria, makes the protease work and stops amylase.

›Cells in the stomach wall also produce protease enzymes to digest proteins into amino acids.

Animation showing all the food tests.

Final stages of digestion

›The liver produces bile which is stored in the gall bladder. pH 7.5-8.0

›The gall bladder releases bile via the bile duct into the duodenum, the first part of the small intestine.

›Humans produce 1L of bile a day

›Bile is alkaline and neutralises stomach acid.

›Bile breaks up large globules of fats and oils (with a small surface area) to form a suspension of many small droplets (large SA). This increases the surface area to volume ratio for chemical digestion.


The movement of simple molecules from the digestive system to the circulatory system for dispersal throughout the body.


Villus role and structure

Role of microvilli, capillary network and lacteal

Ileum is the second part of small intestine where absorption of nutrients from digested food occurs.

The walls of the small intestine are covered with the finger-like projections called villi.

Villi maximise the absorption process by increasing the surface area where nutrients can enter the blood stream.

Villi have very thin surface so nutrients can easily be absorbed across.

Villi are well supplied with blood by containing many blood vessels (capillaries), allowing many nutrients to be absorbed into the blood stream.

Use of food at the cell level

The proteins, lipids, and polysaccharides that make up most of the food we eat must be broken down into smaller molecules before our cells can use them—either as a source of energy or as building blocks for other molecules. The breakdown processes must act on food taken in from outside, but not on the big molecules inside our own cells. Stage 1 in the enzymatic breakdown of food molecules is therefore digestion, which occurs either in our intestine outside cells, or in a specialized organelle within cells, the lysosome. In either case, the large molecules in food are broken down during digestion into their smaller parts—proteins into amino acids, polysaccharides into sugars, and fats into fatty acids and glycerol—through the action of enzymes. After digestion, the small organic molecules derived from food enter the cytosol of the cell, where their gradual oxidation begins. As illustrated in Figure 2-70, oxidation occurs in two further stages of cellular catabolism: stage 2 starts in the cytosol and ends in the major energy-converting organelle, the mitochondrion


Respiration is the process of releasing energy from the breakdown of glucose. Respiration takes place in every living cell, all of the time and all cells need to respire in order to produce the energy that they require.

Aerobic respiration

Aerobic means “with air”. This type of respiration needs oxygen for it to occur so it is called aerobic respiration. The word equation for aerobic respiration is:

Glucose + Oxygen

Carbon dioxide + Water + Energy

The chemical equation is:

C6H12O6 + 6O2

6CO2 + 6H2O + 2900 kj

It is important that you learn both the word and chemical equation.In the above equations we see that glucose is broken down by oxygen to release energy with carbon dioxide and water being produced as by-products of the reaction. Approximately 2900 kj of energy is released when only one glucose molecule is broken down by six oxygen molecules. The released energy is used to make a special energy molecule called Adenosine triphosphate (ATP). ATP is where the energy is stored for use later on by the body.