The Nature and Variety of Organisms

The 8 characteristics

-Movement

-Respiration

-Sensitivity

-Control
-Growth

-Reproduction

-Excretion

-Nutrition

(MRS. C GREN)

Movement

Ability to move (towards-water, food) and (away-predators, poisons)

Respiration

Releasing energy from food in a process called respiration

2 types of Respiration

-Aerobic

-Anaeorobic

Sensitivity

Detecting and responding to changes (stimuli) within their surroundings

Control

Regulating and coordinating body processes (temperature, water content)

Growth

Permanent increase in size until maturity

Reproduction

Producing offspring (for specie survival)

Excretion

Removing waste products (carbon dioxide, urine)

Nutrition

Taking in nutrients for energy and raw materials for growth and repair

Nutrients for a balanced diet include:

-Carbohydrates

-Proteins

-Fats (Lipids)

-Vitamins

-Minerals

-Fibre(Roughage)

-Water

Organism with more than one cell

Multicellular

Organism consisting of a one cell

Single cell

Eukaryotic

Cells that are complex

Prokaryotic

Cells that are simple and small

Specificities of Eukaryotic Cells

-Has a nucleus.

-Has membrane-bound organelles.

-DNA is inside the nucleus

(Includes animals, plants, fungi, and protists)

Specificities of Prokaryotic Cells

-No nucleus.

-No membrane-bound organelles

-DNA free in the cytoplasm

-Usually have a cell wall

(Includes bacteria)

Level of Organisation

Organelle-Cell-Tissues-Organs-Organ Systems

Nucleus

Contains DNA and controls the cell's activities

Cell membrane

Controls what enters and leaves the cell.

Cytoplasm

Jelly-like substance where most chemical reactions occur.

Mitochondria

Site of aerobic respiration => releases energy

Ribosomes

Site of protein synthesis (makes proteins)

Cell wall (Plant)

Rigid structure (made out of cellulose) supports and strengthens the cell

Chloroplasts

Site of photosynthesis, contain chlorophyll

Large permanent Vacuole

Contains cell sap (weak solution of sugar and salts) => Keeps the cell rigid

Tissues

A group of similar cells that work together to carry out a particular function

Example of Tissues (Animal):

Muscle tissue – Contracts to produce movement

Example of Tissues (Plants):

Xylem tissue – Transports water and minerals.

Organs

A group of different tissues that work together to perform a function

Example of Organs (Animal):

Heart - Muscle tissue, nervous tissue, epithelial tissue, connective tissue

Example of Organs (Plants):

Leaf (plant organ) - Palisade mesophyll, spongy mesophyll, epidermal tissue, xylem, phloem

Organ System

A group of organs that work together to carry out a specific function.

Example of Organ Systems ( Animal):

Circulatory system - Organs = Heart, blood vessels => Function = Transports blood, oxygen, and nutrients

Example of Organ Systems (Plant):

Shoot system- Organs = stem + leaves + flowers => Function = Supports the plant, Transports substances, Carries out photosynthesis, and Enables reproduction

Specialised cells

Specialised cells are cells that have a specific structure and function, adapted to carry out a particular job in an organism

Stem cells

Stem cells are unspecialised cells that can divide and develop into different types of specialised cells.

Example of Specialised cells

Red blood cell

-Carries oxygen (function)

-Contains haemoglobin, biconcave shape, no nucleus (adaptation)

Example of Stem cells

Embryonic stem cells

-Early embryos (found in)

-Almost any type of specialised cell (can become)

-Nerve cells, muscle cells, or skin cells (example)

Cell differentiation

Process in which a cell changes to become specialised for its job

What happens when the cell changes

They develop different organelles

Turn into different types of cell

which allow them to carry out specific functions

Where are the adult stem cells located

Bone marrrow

How limited are adult stem cells

Adult stem cells can only differentiate into a limited number of specialised cell types, usually those related to the tissue they come from

Cloning

Cloning is the production of genetically identical cells or organisms

How are Stem cells related to medicinie

Stem cells can treat diseases because they can divide and differentiate into healthy specialised cells

Replacing damaged or dead cells

Advantages and Limitations of Stem cells in medicine

Advantages	Limitations
Replace damaged cells with healthy ones	Ethical concerns over destroying embryos
Can treat diseases such as leukaemia	Risk of immune rejection
May grow replacement tissues or organs	May form tumours if cells divide uncontrollably
Can improve quality of life and save lives	Expensive and many treatments are still being researched

What are the 3 groups

Animals, Plants, Fungi

Animals (eukaryotic)

Multicellular organisms that obtain food by eating other organisms (consumers)

Plants (eukaryotic)

Multicellular organisms that make their own food by photosynthesis using sunlight, carbon dioxide, and water (producers)

Fungi (eukaryotic)

Organisms that cannot make their own food.

They obtain nutrients by breaking down and absorbing dead or decaying organic matter (decomposers)

Animals (features)

-Multicellular

-Cells have no cell wall or chloroplasts

-Cannot make their own food (eat other organisms)

-Usually able to move (nervous coordination)

-Store carbohydrates as glycogen

Plants

-Multicellular

-Cells have cell walls (cellulose)

-Contain chloroplasts for photosynthesis

-Large permanent vacuole

-Make their own food

-Store carbohydrates as sucrose or starch

Fungi

-Usually multicellular (yeast is single-celled)

-Cells have cell walls (chitin)

-No chloroplasts

- Cannot photosynthesise

-Feed by absorbing nutrients from dead or living organisms

-Mycelium: A network of thread-like structures called hyphae that makes up the main body of a fungus (mucor)

Hyphae

Tiny thread-like structures that grow through the material the fungus is feeding on

Mycelium

Large network of hyphae

Protoctists(eukaryotic)

Protoctists are mostly single-celled organisms with a nucleus that do not belong to the animal, plant, or fungi kingdoms

Key features of Protoctists

-Usually unicellular (single-celled)

-Have a nucleus (they are eukaryotes)

-Some can photosynthesise (like algae)

-Others feed on other organisms (like protozoa)

-Mostly found in water or damp environments

Bacteria

Bacteria are single-celled microorganisms that do not have a nucleus or other membrane-bound organelles.

Key features of Bacteria

-Unicellular (single-celled)

-No nucleus (they are prokaryotes)

-DNA is a single circular loop free in the cytoplasm

-Have a cell wall, cell membrane, and cytoplasm

-Some have flagella to help them move

- Reproduce by binary fission

Key features of Virus

-Much smaller than bacteria

-Not a cell (it is acellular)

-Contains genetic material (DNA or RNA)

-Surrounded by a protein coat (capsid)

-Has no nucleus, cytoplasm, or cell membrane

-Can only reproduce inside a host cell

Virus

A virus is a tiny infectious particle that can only reproduce inside a living cell

Pathogen

A pathogen is a microorganism that causes disease

Examples of disease caused by pathogens

-Bacteria – e.g. Salmonella, tuberculosis bacteria

-Viruses – e.g. influenza virus, coronavirus

-Fungi – e.g. athlete's foot fungus

-Protoctists – e.g. Plasmodium (causes malaria)

Enzymes

Catalysts produced by living things

Catalyst

A substance which increases the speed of a reaction without being changed or used up in the reaction

How do you make a reaction happen faster

Increasing temp

What are enzymes made of

Proteins

How do enzymes speed up reactions

Lower the activation energy needed for the reaction

What is the active site

The specific part of an enzyme where the substrate binds

What is a substrate

The molecule that an enzyme acts on

What is the enzyme-substrate complex

Temporary structure formed when a substrate binds to an enzyme's active site

What is the lock-and-key model

The idea that an enzyme's active site has a specific shape that only its complementary substrate can fit into

Why are enzymes specific

Their active sites have specific shapes, so only certain substrates can bind

What happens when a substrate enters the active site

It binds to the active site, forming an enzyme-substrate complex, and the reaction occurs

What happens to the enzyme after the reaction

The enzyme is unchanged and can be used again

What happens to enzyme activity as temperature increases

Activity generally increases because particles have more energy and collide more frequently

What happens at the optimum temperature

The enzyme works at its maximum rate

What happens if the temperature becomes too high

Bonds holding the enzyme's structure break, changing the shape of its active site

What does it mean when an enzyme is denatured

Its active site has changed shape, so the substrate can no longer bind properly

Can a denatured enzyme usually return to its original shape

No. Denaturation is usually permanent

How does pH affect enzymes

Each enzyme has an optimum pH where it works fastest

What happens if the pH is too high or too low

The enzyme's bonds can be disrupted, changing the shape of its active site

What can extreme pH cause

Denaturation of the enzyme

What factors affect enzyme activity

Temperature, pH, substrate concentration and enzyme concentration

What happens when substrate concentration increases

The reaction rate increases because there are more substrate molecules available to bind to enzymes

Why does the rate eventually stop increasing

All the enzyme active sites become occupied, so the enzymes are working at their maximum rate

What happens when enzyme concentration increases

The reaction rate generally increases because there are more active sites available

Which enzyme breaks down starch

Amylase

What does amylase break starch into

Maltose

Which enzyme breaks down proteins

Protease

What does protease break proteins into

Amino acids

Which enzyme breaks down lipids

Lipase

What does lipase break lipids into

Fatty acids and glycerol

Why are enzymes important in digestion

Break large insoluble food molecules into smaller soluble molecules that can be absorbed