module 2: organisation of living things 2... · living things are divided into: autotrophs: living...

MODULE 2:ORGANISATION OF LIVING THINGS

PART 1UNICELLULAR, COLONIAL AND MULTICELLULAR ORGANISMS

UNICELLULAR ORGANISMS

◼ They are made of only one cell

◼ Responsible for all its own life processes

◼ Unicellular eukaryotc organisms can carry out all the necessary life processes in a more efcient manner than the prokaryotes by means of specialised organelles.

◼ Directly exposed to the external environment

◼ E.g. Diatom

Compare the diference between unicellular, colonial and multcellular organisms

UNICELLULAR ORGANISMS

◼ High surface-area-to-volume rato due to small size

◼ This enables all required substances (nutrients, gases, water) to move across the cell membrane into all parts of the cell for its functoning.

◼ Wastes efciently removed from all parts of the cell by movement through the cell membrane.


COLONIAL ORGANISMS

◼ Group of identcal single-celled organisms collectvely called a colony.

◼ All individuals are capable of carrying out each functon necessary for life.

◼ Some colonial organisms contain cells that have specialised functons that coordinate with other cells in the colony.


COLONIAL ORGANISMSExample: Volvox

htps://youtu.be/dqq0vgSJiQ


https://youtu.be/dqq0vgSJiQQ

MULTICELLULAR ORGANISMS

◼ Made up of diferent types of cells

◼ Similar cells are grouped together and perform specialised functons that combine together for efcient functoning of the organism.

◼ Cells can not live independently unlike unicellular and colonial organisms.

◼ E.g. Humans, plants


CELL STRUCTURE AND FUNCTIONThe structure of a cell is related to the partcular functon of that specialised cell

◼ Red blood cells are very small and have a partcular shape, allowing them to pass through capillaries and maximise SA:V forefcient gas exchange.

◼ Elongate palisade cells in a leaf are fatened to give greater SA:V to maximise absorpton of oxygen and water.


CELL STRUCTURE AND SPECIALISATION IS RELATED TO FUNCTION

Stem cells are undiferentated cells with no specialised structure or functon.

Specialised cells are formed when diferentaton of the stem cells occurs and they develop suitable structural features that allow them to carry out their specifc functons.

The type of cell that is formed is determined by the locaton of the undiferentated cells in the organism and the partcular genes that are switched on.

Stem cells can be either embryonic or adult stem cells. In plants, specialised cells are formed by the diferentaton of meristematc tssue.

PART 2STRUCTURAL ORGANISATION IN MULTICELLULAR ORGANISMS

LEVELS OF ORGANISATION

Atoms Molecules Organelles Cells Tissues Organs Systems Organism

Justfy the hierarchal structural organisaton of organelles, cells, tssues, organs, systems and organisms

Justfy the hierarchal structural organisaton of organelles, cells, tssues, organs, systems and organisms

Examples< Mitochondria

< Cardiac Muscle cells

< Cardiac Muscle tssue

< Heart

< Cardiovascular system

< Human

DIFFERENTIATION AND SPECIALISATION

Cell Diferentaton Occurs when a young unspecialized cell develops into a more mature state and becomes specialized to carry out partcular functons.

Investgate the structure and functon of tssues, organs and systems and relate those functons to cell diferentaton and specialisaton


Cell Specialisaton Leads to a division of labour in multcellular organisms, allowingcertain tasks to be carried out more efciently.


BACKGROUND

There are four main types of animal tssue: epithelial tssue, connectve tssue, nervous tssue and muscle tssue.

There are many diferent forms of each of these types of tssues. The four main types of plant tssue are meristematc tssue, vascular

tssue, dermal tssue and ground tssue. The arrangement of cells into tssues, organs and systems in multcellular

organisms maximises the efcient functoning of the organisms. The interacton and cooperaton between cells, tssues, organs and

systems provides multcellular organisms with abilites that are beyond the limitatons of a single cell.


Cells are found at the tps of rots and shoots and is where cell division occurs to produce new growth

- PLANT TISSUE

Meristematc1


1. Epithelial

2. Muscle

3. Nervous

4. Connectve

DIFFERENTIATION AND SPECIALISATION- ANIMAL TISSUE



Cells cover many surfaces and linings of body cavites, actng as a protectve layer and a barrier against infecton or water loss. Examples:

- Inside mouth (cheek cells)- Outer layer of skin- Stomach lining- Surrounding outside of organs

- ANIMAL TISSUE

Epithelial1



Specialised to convert chemical energy from ATP into mechanical energy for movement.

- ANIMAL TISSUE

Muscle2



Contain dendrites which pick up signals from the brain and send them out to other parts of the body using impulses (electrical signals).

- ANIMAL TISSUE

Neurons3



NeuronsContain dendrites which pick up signals from the brain and send them out to other parts of the body using impulses (electrical signals).

- ANIMAL TISSUE

3



Consists of an extracellular matrix with cells scatered throughout.

Examples:- Collagen fbres provide strength- Elastn provides fexibility

- ANIMAL TISSUE

Connectve4


1. Meristematc

2. Vascular

3. Dermal

4. Ground

DIFFERENTIATION AND SPECIALISATION- PLANT TISSUE



Cells are responsible for the transport of substances around the plant and are found in the roots, stems and leaves.

Example:-Xylem- Phloem

- PLANT TISSUE

Vascular2


DIFFERENTIATION AND SPECIALISATION- PLANT TISSUE

2



Cells protect the plant and controls interactons with its’ surroundings. They are found on the outer surface of stems and leaves

- PLANT TISSUE

Dermal3



Cells make up the rest of the internal plant structure, specialized for food storage, structural support and photosynthesis.

- PLANT TISSUE

Ground4


Diferent types of tssues that are grouped together to perform a partcular functon are called organs.

HeartOrgan that contains muscle tssue, connectve tssue,nerve tssue and epithelial tssue. These tssues are composed of specialized cells. The tssues work together (as the heart) to ensure it functons efciently and efectvely.

DIFFERENTIATION AND SPECIALISATION- ORGANS


Diferent organs are grouped together to form an organ system that is responsible for a partcular body functon

Cardiovascular SystemTransport system responsible for the movement of oxygen, nutrients and waste around the body. This system consists of several organs working together (heart, veins, arteries, capillaries, blood)

DIFFERENTIATION AND SPECIALISATION- SYSTEMS


NUTRIENT AND GAS REQUIREMENTSWHAT IS THE DIFFERENCE IN NUTRIENT AND GAS REQUIREMENTS BETWEEN AUTOTROPHS AND HETEROTROPHS?

HETEROTROPH / AUTOTROPH REVIEWLiving things are divided into:

◼ Autotrophs:Living things that produce own organic materials

◼ Heterotrophs:Living things that consume organic material produced by others

TYPES OF AUTOTROPHS

Vascular

Most of plants on Earth.

Have a transport system including Xylem and Phloem.

Non-vascular

Don’t possess a transport system. No Xylem or Phloem.

Live in their nutrient source.

◼Leaf – absorbs sunlight, exchange gases, transpiration and carry out photosynthesis◼Stem – transport between roots and leaves via xylem and phloem, structural support

FUNCTIONS OF PLANT STRUCTURES:THE ROOT SYSTEM

Investigate the function of structures in a plant

Anchoring plant.

Absorbing water and inorganic nutrients from the soil.

Large surface area to absorb efciently

FUNCTIONS OF PLANT STRUCTURES:THE ROOT SYSTEM


Large surface area is achieved through:

◼Branching of roots

◼Root hairs in younger part of root tips◼Epidermal cells protrude

outwards into soil.

◼ Flat nature of epidermal cells increase exposed surface

FUNCTIONS OF PLANT STRUCTURES:THE SHOOT SYSTEM


For Photosynthesis:◼ Water moves into roots

through osmosis

◼ Mineral ions move into roots by difusion

◼ No photosynthesis in root cells (no chloroplast/no sun)

◼ Aerobic respiration occurs

FUNCTIONS OF PLANT STRUCTURES:THE STEM


Xylem

Absorbed from soil through the root system.

Transport of:◼ Water

◼ Water-soluable nutrients

◼ Minerals



Phloem

Conductive tissue composed of thin-walled cells.Movement from one part of plant to another.

Transport of:◼ Sugars (as dissolved sucrose)

SUMMARY◼ The main functions of the root system are to anchor the plant in the soil and absorb water and mineral ions.

◼ A large surface area is required for efcient absorption of water and mineral ions.

◼ This large surface area is achieved with fattened epidermal cells that possess fne extensions called root hairs.

◼ Branching root systems increase the surface area for absorption. ?Water moves from the soil into the root by osmosis.

◼ Mineral ions usually move into the root by difusion, but if the concentration gradient is too low they are moved in by facilitated difusion or active transport.

◼ Root cells do not contain chloroplasts and do not photosynthesise but, as with all living cells, they carry out aerobic cellular respiration.

◼ Oxygen gas difuses into the root cells and carbon dioxide gas difuses out

PART 2GAS EXCHANGE IN AUTOTROPHS AND HETEROTROPHS

Photosynthesis

Investgate the biochemical processes of photosynthesis, cell respiraton and the removal of cellularproducts and wastes in eukaryotc cells

PHOTOSYNTHESIS◼ The main function of the leaf is to absorb sunlight and carry out photosynthesis to produce the organic compound glucose.

◼ The thin, fat structure and orientation of the leaf maximise surface area for absorption of sunlight.

◼ A waxy cuticle minimises water loss from the leaf. ◼ Palisade cells containing many chloroplasts are

lined up vertically near the upper surface of the leaf to absorb sunlight.

◼ Spongy mesophyll cells are loosely and irregularly organised to allow easy movement of gases through the leaf.

PHOTOSYNTHESIS◼ Transport tissue in the leaf is organised into veins. This provides support as well as a pathway for the movement of water and the products of photosynthesis.

◼ Guard cells, which are often more numerous on the underside of the leaf, change shape to open and close ‘pores’ known as stomata.

◼ The gases oxygen and carbon dioxide are exchanged between the inside and outside of the leaf through stomata.

◼ All plant cells carry out cellular respiration both at night and during the day.

◼ Oxygen produced in photosynthesis is used in this process.

EXTRA STUFF-IMPORTANT

Radioisotopes are forms of an element that emit radiaton, which can be detected by a number of means. They act as tracers and are used to follow the pathways of molecules involved in photosynthesis.

Radioisotopes were used to determine that oxygen produced in photosynthesis came from the water molecule and not the molecule of carbon dioxide.

Carbon-14 added to the carbon dioxide supply traced the movement of the glucose produced through the plant.

New technologies can be used to produce 3D images of the structures and pathways involved in the movement of products of photosynthesis.

GAS EXCHANGE IN PLANTS AND ANIMALS

3 Groups to research one of the structures and report to the class.

◼Macroscopic Structures:◼Respiratory System in animals

Investigate the gas exchange structures in animals and plants through the collection of primary and secondary data and information

Microscopic Structures◼ Gas exchange in plants occurs through the stomata and

lenticels. ◼ When guard cells fll with water, they bend outwards and

open the stoma, allowing for gas exchange. ◼ When water is lost from the guard cells they straighten and

close, preventing both gas exchange and water loss. ◼ Plants have to balance their requirement for gas exchange

and the necessity for water conservation. ◼ Stomata open in light and close in the dark. ◼ Lenticels are pores through which gaseous exchange occurs

in the woody parts of plants, such as the trunks and branches of trees and woody shrubs

Macroscopic Structures:◼ The movement of gases between the external environment (alveolar air) and internal environment (bloodstream) is known as gaseous exchange.

◼ Diferent animals possess diferent specialised structures to exchange gases with their environment.

◼ Common characteristics of all respiratory surfaces are that they have:– a large surface area– thin, moist surfaces– a close proximity to transport system– the concentration gradient maintained for continued difusion.

◼ Terrestrial animals have internal respiratory systems to reduce water loss.

Macroscopic Structures:◼ Alveoli, located in the lungs, are the gaseous exchange

surfaces in mammals.◼ Millions of alveoli in the lungs create a very large surface

area for the exchange of gases.◼ The surface of the alveoli is very thin and moist. Many

capillaries surround each alveolus.◼ Oxygen difuses from where it is more concentrated in the

alveoli into the capillaries where it is less concentrated.◼ Carbon dioxide is more concentrated in the capillary and

difuses out into the alveolar space.

Macroscopic Structures:◼ Fish have specialised structures called gills to absorb the

small amount of oxygen that is dissolved in water. Gills are well supplied with blood capillaries.

◼ Insects exchange gases via pores called spiracles, which lead to tracheal tubes, which then branch into smaller tubes called tracheoles.

◼ The tracheoles bring air directly to and from the cells of the insect. Blood is not involved in the transport of gases in an insect

PART 3PHOTOSYNTHESIS

PHOTOSYNTHESIS◼ A Dutch physician born in

1730, discovered photosynthesis—how plants turn light into energy. In this process, chlorophyll in plant cells absorbs light and uses it to convert atmospheric carbon dioxide and water to sugars, which the plants consume for energy.

PART 4THE MAMMALIAN DIGESTIVE SYSTEM

Continued….◼ Digestive enzymes enable the chemical breakdown of large, complex molecules into the small molecules that can then be absorbed into the transport systems of the body.

◼ Complex molecules and their simple products formed after digestion are listed below:– Proteins are broken down into amino acids.– Carbohydrates are broken down into simple sugars, such as glucose.– Lipids are broken down into glycerol and fatty acids

MAMMAL SYSTEM◼ Digestion is the breakdown of

food into particles small enough to be absorbed into the bloodstream.

◼ Mechanical digestion is the physical breakdown of the food into smaller pieces to increase the surface area for the action of enzymes.

◼ The teeth and the churning motion of the stomach are the main ways in which mechanical digestion occurs.

MAMMAL DIGESTION

◼Mechanical digestion occurs in the mouth by use of the teeth and the tongue.

◼ Chemical digestion begins in the mouth with the enzyme salivary amylase breaking the complex carbohydrate starch down into simpler sugars.

◼Mechanical digestion is continued in the stomach. ◼ Pepsin begins the chemical digestion of proteins in

the chyme to form shorter peptide chains and the digestion of nucleic acids to nucleotides

MAMMAL DIGESTION◼ The small intestine is very long and folded and has three regions: the duodenum, the jejunum and the ileum.

◼ Most digestion is completed in the duodenum.

◼ The pancreas releases many diferent digestive enzymes and bicarbonate ions.

◼ Bicarbonate ions neutralise the acidic chyme as it enters the small intestine.

◼ Bile produced by the liver and stored in the gall bladder emulsifes fat molecules to increase surface area for breakdown by lipases.

MAMMAL DIGESTION

◼Other enzymes complete the chemical breakdown of larger molecules.

◼Most absorption of products of digestion occurs in the jejunum. illi are microscopic projections on the wall of the jejunum that are one cell thick. There are blood capillaries and lymph vessels in close contact with these cells. Small molecules difuse or are actively transported through the walls of the villi into the capillary or lymph vessels to be distributed throughout the body.

MAMMAL DIGESTION

◼Water and mineral salts are absorbed from the large intestine into the bloodstream.

◼ The remaining undigested material is called faeces and is stored in the rectum before being eliminated from the body.

◼Digestive products absorbed into the body are used in many diferent ways, including for structural purposes and for energy storage

MAMMAL DIGESTION

◼Water and mineral salts are absorbed from the large intestine into the bloodstream.

◼ The remaining undigested material is called faeces and is stored in the rectum before being eliminated from the body.

◼Digestive products absorbed into the body are used in many diferent ways, including for structural purposes and for energy storage

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PART 5REQUIREMENTS OF AUTOTROPHS AND HETEROTROPHS

REQUIREMENTS◼ Autotrophs and heterotrophs require gases and nutrients to maintain efcient and efective metabolic function.

◼ Both heterotrophs and autotrophs require inorganic and organic substances, water and oxygen gas. Autotrophs also require carbon dioxide gas.

◼ Heterotrophs need to take in all of their nutrients. Autotrophs produce their own organic nutrients using the energy from the sun, but need to obtain water, mineral ions and the gases carbon dioxide and oxygen.

◼ Autotrophs manufacture their own glucose and other organic substances from inorganic nutrients.

◼ Heterotrophs must obtain all of their organic nutrients by consuming autotrophs or other heterotrophs

TRANSPORTHOW DOES THE COMPOSITION OF THE TRANSPORT MEDIUM CHANGE AS IT MOVES AROUND AN ORGANISM?

TRANSPORT SYSTEMS

Blue: the input

Red : the output

PART 1PLANT TRANSPORT SYSTEMS

PLANT TRANSPORT SYSTEMS

Investigate transport systems in animals and plants by comparing structures and components using physical and digital models

Xylem: a specialised tissue for the transport of water and dissolved mineral ions from the roots to the leaves. This movement occurs in only one direction – upwards from the roots

Phloem: Phloem is specialised tissue that transports sugars and other products of photosynthesis from the leaves, where they are produced, to the rest of the plant where they are either used or stored

◼ Transport systems in plants carry water and mineral ions in one direction only, from the roots to the leaves, in the xylem tissue. The products of photosynthesis are delivered wherever required around the plant in the phloem tissue.

◼ Xylem tissue is composed of xylem vessels and xylem tracheids.

◼ Xylem vessels are long, thin, continuous tubes composed of dead tissue with lignin-strengthened walls.

XYLEM

XYLEM◼ The transpiration-cohesion-tension theory currently explains the movement of substances up the xylem vessels.

◼Water evaporates from the leaves and creates tension, which pulls more water from the veins and then up the xylem vessel.

◼ Cohesion between water molecules and adhesion between the water molecules and the walls of the xylem maintain the column of water. When molecules of water are pulled up, other molecules follow.

◼ A small amount of root pressure forces the water already present in the xylem vessel upwards

TRANSPIRATION COHESION TENSION THEORY- XYLEM

◼ This theory has at its core the evaporation of water from the leaves (transpiration) creating a suction pull of water up the stem from the roots. The movement of this column of water up the stem due to the evaporative pull of transpiration is known as the transpiration stream

STOMATA◼ Stomata are tiny pores found on the

under surface of the leaf.

◼ Guard cells are the only epidermal cells with chloroplasts

◼ In daylight when the stomata opens, Carbon dioxide can enter the leaf and Oxygen to exit.

◼ During the night, stomata are closed to conserve energy and photosynthesis cannot take place in the dark.

Investigate the exchange of gases between internal and external environments of plants and animals

STOMATA OPENING


STOMATA CLOSING


PHLOEM

Source-sink theory; PHLOEM

◼ Glucose in plants are either stored as starch or converted to sucrose and distributed to all parts of the plant. The distribution process is called translocation and occurs in the phloem tissue.

◼ Substances transported in the phloem move in whichever direction is required. Amino acids and some mineral nutrients are also carried with sucrose in phloem. When sucrose reaches the cells, it may be converted back to glucose for cellular respiration or to starch for storage.

Continued…

◼ Movement occurs from the region of high pressure to the region of low pressure. The high-pressure region is in close proximity to where the sucrose is produced and is known as the source. The low-pressure region is where the sucrose is required and is known as the sink.

PART 2ANIMAL TRANSPORT SYSTEMS

ANIMAL TRANSPORT SYSTEMS

◼The transport systems of multicellular animals can be divided into two types: open and closed. These systems are similar in that they each contain the heart as a driving mechanism, a fuid that transports substances and a system of vessels

OPEN AND CLOSED CIRCULATORY SYSTEMS◼Open systems◼An open circulatory system is made up of one or

more hearts and open-ended blood vessels. It is not sealed.

◼Closed systems◼A closed circulatory system is found in all

vertebrate animals and is made up of blood vessels and a heart, which form a sealed system

OPEN SYSTEMS

Open circulatory systems exchange only nutrients and wastes with cells of the organism’s body – gases are exchanged via a diferent system.

When the long, pulsating vessel (the heart) contracts, it pumps the transport fuid away from it and into shorter vessels near the head end of the body that empty into large spaces in the body cavity called sinuses.

The transport fuid in an open circulatory system is called haemolymph and is a mixture of blood and tissue fuid. Haemolymph fows into the sinuses in the body cavity, bathing the cells directly.

EXAMPLE

CLOSED SYSTEM

◼ This system transports nutrients and oxygen to all cells and carries wastes away from cells.

◼ The transport fuid is blood, which is contained in vessels at all times and never fows through body cavities.

◼ The heart may be two-chambered (as in fsh), three-chambered (as in frogs and some reptiles), or four-chambered (as in other reptiles, all birds and mammals).

◼ Any chemical substances required by cells leave the capillaries in a dissolved form and move to the fuid called tissue fuid that surrounds the cells.

TWO TRANSPORT SYSTEMS IN MAMMALS

BLOOD VESSELS

PART 3CHANGES IN COMPOSITION

KEY POINTS◼ Blood composition changes as it moves around the body

and depends on the organ it is moving through◼ In all organs and tissues except the lungs, blood loses

oxygen and gains carbon dioxide. In the lungs, it gains oxygen and loses carbon dioxide.

◼ In all organs except the small intestine, blood loses nutrients, such as the products of digestion and gains wastes. Blood gains products of digestion in the small intestine.

◼ In the kidneys, blood has less urea when it leaves, and the concentration of water and salts will have changed according to the needs of the body.

KEY POINTS◼ In the kidneys, the amount of urea is decreased

because the kidneys flter nitrogenous wastes out of the blood.

◼ Blood leaving the kidneys has the lowest percentage of nitrogenous wastes. Excess water and salts are removed from the blood.

◼ In the large intestine, water, salts and vitamins are absorbed into the blood.

◼When blood passes through endocrine glands, hormones are added to the blood

module 2: organisation of living things 2... · living things are divided into: autotrophs: living...

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