Transcript Chap 5 - CRCBiologyY11

Unit 1 – Unity and diversity
AOS 2 – Functioning organisms
Chapter 5
Obtaining energy and nutrients for life
Heterotrophs and autotrophs
All living organisms require nutrients in order to maintain
normal bodily functions. Organisms can be classified based
on the main way they obtain the nutrients they require for
living. They can be classified into one of two groups:
- Autotroph: an organism that is able to synthesise (make)
their own organic compounds from simpler organic
compounds.
- Heterotroph: an organism that cannot synthesise organic
compounds, but rather has to obtain them by eating other
organisms.
Autotrophs
• Autotrophs are organisms that synthesise the nutrients they
require for energy. The process by which autotrophs obtain
this energy is called photosynthesis.
• As discussed in chapter 3, photosynthesis refers to a
chemical reaction that converts the simple organic
molecules water and carbon dioxide to energy rich organic
compound glucose.
• This glucose is then converted to a form of energy that cells
are able to use, called adenosine triphosphate (ATP).
Photosynthesis in detail
•
Photosynthesis involves a series of complex biochemical
reactions in which sunlight energy is converted to chemical
energy in sugars. It occurs in the chloroplasts of plant and
algae.
•
Photosynthesis involves two sets (phases) of reactions:
1) Light dependant phase – as the name suggests requires
sunlight.
2) Light independent phase – occurs independent of light
but depends on the products of the first light dependent
phase.
Phases of photosynthesis
• Phase (shift) 1
Inputs (reactants) – Sunlight, water (H20) and adenosine diphosphate (ADP)
Outputs (products) – Oxygen, hydrogen ions (H+) and adenosine triphosphate
(ATP)
• Phase (shift) 2
Inputs (reactants) – Carbon dioxide (CO2), hydrogen ions (H+) and adenosine
triphosphate (ATP)
Outputs (products) – Glucose (C6H12O6) and adenosine diphosphate (ADP)
• The hydrogen ions (H+) and ATP from shift 1 are used as
the reactants for shift 2. Conversely, the ADP produced by
shift 2 is used as a reactant in shift 1.
Worded reactions
• Write a worded reaction for the:
a) Light dependent phase, and
b) Light independent phase.
Answers:
a)
water + ADP
b)
•
sunlight
chlorophyll
oxygen + hydrogen ions + ATP
carbon dioxide + hydrogen ions + ATP
glucose + ADP
Write the summarised worded and chemical reaction for
photosynthesis.
Plant structures and photosynthesis
• Leaves: main structure for intake of CO2 through stomatal
pores, contain many chloroplasts fro photosynthesis, flat
shape increases SA:V to allow greater sunlight exposure,
thinness of the leaf increases ability of gases to diffuse.
• Stems: have two different types of vessels to transport
different substances throughout the plant;
-
xylem transports water and minerals from roots to all parts of the plant above
ground that need them, and
phloem transports glucose from photosynthetic tissues to non photosynthetic
tissues.
• Roots: covered in root hairs to increase the SA:V which
water and dissolved minerals can be uptaken into the plant.
Revision tasks
• Copy key ideas from page 100 into your exercise book.
• Complete quick-check questions 1-7 from page 100.
Heterotrophs
• Any organism that is unable to make their own organic
material must obtain it from eating another organism.
• Organisms that eat or consume other organisms in order
to obtain nutrients required for living are called
heterotrophs.
• As a group, heterotrophs exploit a wide range of foods –
plant matter, flesh of other animals living or dead, even
faecal matter.
• Read through ‘Changes through time’ and ‘Food from the
bush’ pages 101-102.
Requirements for digestion
•
•
•
Some simple nutrients can be absorbed by the body, while
other more complex compounds need to be broken down.
Digestion is the process by which food is broken down
into simple compounds that can be utilised by the body.
Generally, four steps of digestion occur before a substance
can become available for use by the cells of an animal:
1) Ingestion – intake of food into the mouth
2) Mechanical breakdown – break down of food involving moving parts of the
body. Occurs in two parts, firstly by chewing in the mouth and secondly by the
churning of the stomach, mixing the food around.
3) Chemical breakdown – secretion or various digestive enzymes onto the food
particles to further break down food particles into smaller and smaller
particles.
4) Absorption – organic molecules pass through the lining of the intestinal walls
into the blood stream to be distributed to cells.
Mechanical breakdown of food
• Jaws and teeth
The jaws surround the mouth and are opened and closed by
muscles. Teeth are the hard bony appendages found in the
jaws of many animals. Movement of toothed jaws breaks
food down into smaller pieces.
The structure of the teeth and jaws relates to the diet of the
animal.
Example 1 – Tasmanian devils
These animals are carnivorous, meaning they eat the flesh of
other animals. This requires sharp teeth and strong jaws.
Example 2 – Horses
Horses are herbivorous, and have large flat teeth to grind the
grass matter that they eat.
• Kinds of teeth
There are four different kinds of teeth found in most
mammals:
- Incisors: cutting/clipping teeth found at the front of the
mouth, used predominantly by herbivores and omnivores.
- Canines: well developed in carnivores,
specialised for tearing flesh from bones.
- Premolars: smaller than molars, flattened
- teeth used for grinding food.
- Molars: large flattened teeth used for grinding food.
Figure 5.12 page 105 – Longitudinal section
through a generalised tooth.
Differences in teeth arrangements
Fig 5.14 on page 106 – Different teeth arrangements in some animals
• Copy key ideas and answer quick check questions on p 106
The digestive system
• Class task – group work presenting the different parts of a
typical vertebrate digestive system
- The mouth and oesophagus – 2 people
- The stomach – 3 people
- The liver and gall bladder – 3 people
- The pancreas – 3 people
- The small intestine (duodenum) – 3 people
- The small intestine (jujenum and ileum) – 3 people
- Absorption in the small intestine – 2 people
- The large intestine, rectum and anus – 4 people
Digestion in herbivores
•
Herbivores are animals that only eat plant matter. Cellulose
is the major carbohydrate found in plants, but it
indigestible by animals. Cellulose can only be broken down
(fermented) by bacteria, and so all animals that eat plant
matter have bacteria living somewhere in their gut.
•
Depending on where the bacteria live in the gut,
herbivores are classified into two groups:
1) Foregut fermenters or
2) Hindgut fermenters
Fermentation
•
Fermentation is the breakdown of cellulose cell wall of
plant cells by bacteria to access the energy found within
plant cell.
1) Foregut fermenters – the foregut is comprised of the oesophagus and
the stomach. As bacteria need to live somewhere, foregut fermenters
either have a modified stomach (known as ruminants) or a modified
oesophagus ( non-ruminants).
2) Hindgut fermenters – the hindgut is comprised of the small intestine
and large intestine. Hindgut fermenters either have a modified small
intestine (caecum fermenters) or a modified large intestine (colon
fermenters).
•
Figure 5.30 page 121 – Cow and koala; two different types of herbivores.
Digestion in nectar and pollen feeders
• Some heterotrophs have highly specialised diets, eating the
pollen or nectar from only one or two different species of
plant.
• Nectar is a sugary substance secreted by flowers to attract
animals to feed and help disperse pollen to other plants
when the animals move on.
• As nectar is made of sugar, very little digestion needs to
occur before the glucose can be absorbed into the blood
stream. As such, the digestive tracts of nectar and pollen
eaters are simple and short. This is also necessary as these
animals are normally tiny in size.
Digestion in carnivores
• Carnivorous animals are those that eat the flesh of other
animals to obtain their energy and nutrients for living.
• Carnivorous mammals do not generally eat any plant
matter, and therefore, do not require complicated, modified
digestive systems that are found in herbivores.
• Similarly, the protein found in animal flesh is much easier to
digest than cellulose, resulting in a fairly short and simple
digestive system, often also characterised by a muscular
stomach.
•
Figure 5.30 page 121 – Tasmanian devil (carnivore) and honey possum (nectar
feeder)
Accessing the energy
• Digestion of plant and animal materials results in simpler
molecules, including glucose, being absorbed into the
bloodstream and transported to all cells.
• But organelles cannot utilise glucose as it is…what do they
do?
• The convert the glucose to ATP through a series of chemical
reactions that occurs in the mitochondria. These reactions
are referred to as cellular respiration, and the chemical
equation can be summarised as below:
Questions and revision
• Answer quick check questions 13-16 from page 123.
• Answer Biochallenge questions 1-4 on page 125.
• Answer the following chapter review questions from pages
125-127
2, 3, 4, 5, 6, 11, 12a, 13 and 14