Module 2: Organisation of Living Things Flashcards
What are unicellular organisms?
+ example
- Contain only one cell responsible for all life processes
- Simple structure
- Limits metabolic reactions
- Large surface area for all substances to diffuse across
- All prokaryotes are unicellular
- EXAMPLE: Bacteria (salmonella)
What are multicellular organisms?
+ example
- Made up of different types of cells
- Similar cells grouped together that communicate to perform specialised functions that combine together for efficient functioning
- Rely less on diffusion and are less efficient
- All cells have the same DNA
- Could not survive by themselves
- EXAMPLE: Animals and Plants
What are colonial organisms?
+ example
- Cells that form a cooperative group (colony) but can survive on their own
- Could be classed as a single celled organism
- More efficient as a colony
- EXAMPLE: Blue-bottle
Example of differentiated cells in humans:
Function:To carry oxygen to cells and remove carbon dioxide – RBCs travel through tiny capillaries to reach every single cell in our bodies
Nucleus-No – to limit size
Organelles-No – to limit size
Size- Red – 7-8um
What is the structure of organised life:
cell tissue organ organ system organism
cell function
smallest unit that can carry out lifes activities
tissue function
group of cells working together to perform specific job
organ
group of tissues working together to perform specific job
organ system function
group of organs working together to perform specific job
Example of organised life;
cell- Cardiomyocytes - These cells must be able to shorten and lengthen their fibres and the fibres must be flexible enough to stretch in order to create a ‘pumping’ motion in the heart.
tissue- Cardiac muscle tissue - Endocardium, Myocardium and Epicardium. This is a specialised form of muscle tissue
organ- heart
organ system- cardiovascular system
organism- humans
organelle summary:
Organelles are the subunit of a cell and consist of a group of functioning biomolecules. Organelles take part in the chemical reactions and interactions in the cellular processes of an organism. A few examples include nucleus and chloroplasts (plant cells), and Golgi bodies and mitochondria (animal cells).
tissue summary
tissue is combination of different types of cells which perform specialized functions. The group of cells that form a tissue are not necessarily identical, but they usually have the same origin i.e. cardiac muscle tissue consists of different types of muscle cells.
nervous tissue
Nervous tissues form organs like the brain and the spinal cord and are capable of sending and receiving electrochemical messages
muscle tissue
Muscle tissues are actively contractile, meaning they can contract and expand. These tissues are useful for producing force and motion.
connective tissue
Connective tissues are fibrous in nature, and they are made up of cells that are separated by an extracellular matrix.
epithelial tissue
- Epithelial tissues cover the surface of body organs.
what are the four types of tissue in the human body?
There are four types of tissue in the human body: nervous, muscle, connective, and epithelial tissues.
organ summary
An organ performs certain functions with the help of different tissues. The major organs of animals include the lungs, brain, liver and heart whereas roots, stem, and leaves are the different organs of plants.
how are organs classified?
on the basis of the functions they perform. For example, in case of animals, the tongue, ears, eyes, skin, and nose are sensory organs, and ovaries and testes are reproductive organs. These units are formed by tissues that serve a common function.
organ system summary
Organs working together to perform certain functions form organ systems. Examples are the circulatory system in animals, and the vascular system in plants. The organs in an organ system are interdependent, i.e. they work in harmony to carry out various body functions
organism summary
An organism could either be unicellular or multicellular. The ones that are closely related can be grouped together under a single genus. An organism can be defined as the fully functional form of a living being that can thrive in a particular environment.
What is a specialised cell?
Specialised cells make up tissues with different types of tissues forming organs that carry out particular function within an organ.
what are stem cells?
All specialised cells originate from cells that are known as stem cells. These stem cells are undifferentiated and are able to divide many times of a long period and become specialised.
What happens to cells once they have specialised?
Once cells have become specialised to form a particular type of cell, they lose their capacity to develop into other types of cells.
What is the relationship between cell structure and function?
The cells of those parts of the body include in exchanging substances with the environment have special structural features to increase their surface area to volume ratio allowing them to exchange the required materials more efficiently.
EXAMPLE – Alveoli
Cells may be flattened to increase their surface area to volume ratio that allow for the more efficient exchange of substances.
Skeletal muscle
Skeletal muscle – long and have striation which are caused by the arrangement of the actin and myosin in them. They are attached to the bones and they cause movement. They are voluntary muscles because they require conscious thought to function
cardiac muscle
fibres are present in the heart and also have striations, the individual cells have connection junctions that are necessary or the coordinated beating of the heart
smooth muscle
do not have striation and their contractions push substances through specialised organs such as the gastrointestinal tract, the blood vessels and the urethra which leads from the bladder.
What is the difference between voluntary and involuntry?
Muscles that are under your conscious control are called voluntary muscles. Muscles that are not under your conscious control are called involuntary muscles
Meristematic tissue:
(Plant cell)
• Found at the tips of roots and shoots
• In woody plants it can also be found in buds and in a ring around the stem
• Inside these tissues’ cells divide to produce new growth
• Cube shaped and very small
CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:
surface area
thin moist surface
close proximity to transport system
greater concentration of gas on one side
CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:
surface area
- Enhanced by folding, branching or flattening
* Allows for a higher rate of diffusion and remove carbon dioxide quicker
CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:
thin moist surface
- Easier diffusion
* Decreases distance for gas to travel
CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:
close proximity to transport system
• Efficient transport
CHARACTERISTICS OF GAS EXCHANGE SYSTEMS:
greater concentration of gas on one side
• To ensure the concentration gradient is upheld
ROLE OF THE RESPIRATORY SYSTEM
- Work with the cardiovascular system
- Transports oxygen to every cell and remove carbon dioxide.
- Needs air which must be taken in from the environment
- Oxygen in atmosphere transferred into the blood
- Different animals use the respiratory system differently
Respiratory system in insects:
Insects have a system of tubes, called tracheae, instead of lungs. These tracheae penetrate right through the insect’s body. Air enters the tracheae by pores called spiracles. These spiracles are found on each side of the insect’s abdomen. Each segment of the abdomen has a pair of spiracles. The air passes into the tracheae which branch into smaller and smaller tubes, in a similar way to the bronchioles in our lungs. The tracheae finally come to an end in the tissues which are respiring. Here in the tissues the oxygen is taken from the air in the tracheae. At the same time carbon dioxide enters the tracheae so that it can be expelled from the body.
Respiratory system in reptiles:
All reptiles breathe through their lungs. The reptile lung has a much greater surface area for the exchange of gases than the lungs of amphibians. Many reptiles’ lungs have little sacs called alveoli, across which gas is exchanged
respiratory system in fish:
Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx.
Pharynx:
Connects the nasal cavity & mouth to the larynx. It is a pathway for both food and air.
Larynx:
Responsible for ensuring food & air go into the proper channels.
Trachea:
Called windpipe. Is very flexible & mobile.
It contains cells which remove foreign particles from the air.
Divides into two bronchi
Epiglottis
A flap of cartilage which prevents food entering.
bronchi:
There are two bronchi leading to each lung.
The bronchi further divide into bronchioles.
Bronchioles:
To ensure that incoming air is supplied to each alveolus.
lungs
Enclose the structures of the body responsible for gas exchange Bronchioles & alveoli.
The lungs are mainly air spaces where internal gas exchange occurs.
alveoli:
Alveoli are small air-filled sacs.
- Increased SA
- Thin moist membrane
- Near blood supply (capillaries)
capillaries
Gas exchange occurs through diffusion (concentration gradient).
stomata and gas exchange in plants:
Most gaseous exchange in plants takes place through the stomata and lenticels. When the stomata are open, gases are able to diffuse through them, but no gas exchange occurs when stomata are closed.
At what time does respiration occur in plants?
night
at what time does photosynthesis occur in plants?
day
What is the stomata?
• Tiny pores that cover epidermis • Gas enters and leaves • Each has a pair of guard cells - Open and close throughout day - Have chloroplast - Reduce water loss • Stomata in grooves - as leaf dehydrates grooves close - reduced water loss • Stomata at bottom of pits - reduced water loss • Sunken of stomata - reduced water loss
Why do multicellular organisms need transport systems?
Cells near the centre of multicellular organisms could not rely on diffusion of substances from the outside alone and therefore require a transport system to deliver nutrients, gases and remove wastes.
Circulatory system characteristics (multicellula rorganisms)
- An efficient carrying capacity
- A large surface area for the exchange of materials
- The effective movement of fluid
- The ability to regulate movement of fluid according to needs
heterotrophs
Organisms that feed on others because they cannot provide their own energy supply
autotrophs
organisms that can make their own energy and do not depend on others.
NUTRITIONAL REQUIREMENTS OF HETEROTROPHS
Obtaining nutrients and energy from food involves several steps:
- Ingestion – intake of food (eating)
- Digestion – breakdown of food into soluble molecules that can be easily absorbed
- Absorption – basic units of food absorbed into the bloodstream
- Assimilation – turning the ‘food’ into tissue
- Egestion – elimination of wastes
Mechanical digestion:
Mechanical breakdown (Physical) – chewing, churning, moving
Teeth and mechanical digestion
- Incisors (front teeth): used to grasp, hold and bite food
- Canines (‘eye’ teeth or ‘fangs’): used for stabbing and gripping prey and for tearing flesh
- Premolars (cheek teeth): used for chewing and for cutting flesh and cracking hard body parts (e.g. bones)
- Molars (back teeth): used for grinding and chewing
chemical digestion:
(Enzymes) - Break down large complex molecules into simpler molecules
structure of the small intestine:
long with a large surface area (good for absorption). It has an internal surface compromised of millions of tiny folds called villi.
function of the small intestine:
absorbs nutrients and minerals from food like glucose, water and salts. Enzymes produced in the pancreas, small intestine, and bile from the liver and gall bladder break down food products to facilitate nutrient and water absorption.
It has many blood vessels that absorb nutrients and waste products and then delivers them to circulatory system.
xylem structure:
Xylem vessels are long, narrow, hollow tubes containing no living material and impregnated with bands or spirals of lignin. They are joined end to end and provide a continuous pathway from the roots through the stem and to the leaves for water transport.
lignin fucntion:
provides strength to stop the vessels from collapsing.
tracheids fucntion:
transport water and are elongated with end walls that taper to a point and also impregnated with lignin
fibres structure and function:
Fibres are also elongated and lignified, providing support to the xylem tissue.
Movement of water in transpiration:
- Explained by Transpiration cohesion theory
- Water against gravity
- Transpiration from stomata (loss of water) created negative pressure
- Negative pressure pulls the water upwards
How is the movement of water assisted?
Assisted by stickiness - Water molecules attracted to each other, temporary bonds that ‘stick’ together, Cohesive and adhesive forces (attractive forces between water molecules)
Cohesion/ adhesion:
The ability of water molecules to stick to other water molecules due to high intermolecular forces
transpiration:
Loss of water from plants by evaporation of water vapour through the stoma of plant leaves.
negative pressure:
When an area of lower pressure than the other surrounding it. Creates a ‘pulling’ force
Phloem function:
sugar transport tissue in plants
Sieve tub elements
living cells without cytoplasm and mitochondria but without other organelles
sieve plates
the perforated transverse walls of the sieve elements which allow sap to flow from one element to the next
companion cells
associated with each sieve element and they are responsible for keeping them alive
translocation
is the movement of materials in plants from the leaves to other parts of the plant. Nutrients, mainly sugars, are created in the leaves during photosynthesis. These are then transported throughout the plant through phloem.
Translocation source:
Place that produces or stores sugar (leaves and roots)
translocation sink:
Place in need of sugar
translocation process:
- Transports sugars from sources to sinks
- Uses active transport to go against the concentration gradient
- Actively transported from a source, creates an area of high concentration, which causes the water to passively more from the xylem to dilute sugar
- Creates temporary pressure causing the movement of materials towards the various sinks
What are the differences between xylem and phloem?
Xylem = dead cells, direction = up, movement of water and minerals Phloem = living cells, direction = up and down, movement of sugars
red blood cells
45%
Disc shaped cells that contain haemoglobin
Transport oxygen, carbon dioxide and haemoglobin
white blood cells
<1%
Bigger than red blood cells
Transports antibody into the plasma to fight pathogens
platelets
<1%
Small, colourless, irregular, sticky surfaces
Clumps blood to control bleeding
plasma
54%
Liquid mainly made up of water
Carries nutrients (glucose, amino acids, proteins, ion, waste products and small amounts of carbon dioxide
veins
Veins return blood to the heart and have thinner walls than those of the arteries. The walls are thinner, and the veins are compressed, propelling the blood towards the heart. Veins have valves which prevent blood from flowing backwards as they work like one-way swing doors.
arteries
Arteries carry blood away from the heart with a strong structure that is able to withstand the high pressure in which the blood is moving. The tissue is made from elastic and collagenous fibres that allow varying volumes of blood to move through at high pressure
capilalries
Capillaries bring blood into close contact with tissues, enabling the exchange of chemical substances between cells and the bloodstream. Their walls are only one cell thick allowing diffusion which iis a slow process, therefore their internal diameter is only slightly larger than red blood cells, slowing down the flow of blood.
open circulation
- Fluid is not combined to vessels
- Circulation is slow
- Transports nutrients not oxygen
- Found in arthropods e.g. insects and mollusc
closed circulation
- Blood moves through the body enclosed in a network of tubes of different sizes that lead to and away from the heart
- Blood circulation is rapid
- Nutrients, wastes and gases are carried by blood
- Found in larger, active animals e.g. mammals, amphibians, birds and fish
