Chapter 9. Coordination and Response

Stimulus is a change in an organism’s environment which is detected by a receptor
Cell that detect stimuli are called receptor cells

The Eye

• Part of the eye that contains the cell receptor is the retina. Retina is sensitive to light
• The front of the eye is covered by a thin transparent membrane n Called the conjuctiva for protection functions. Conjunctiva is always wet or damp with resultant fluid by the lachrymal glands. Tears contain lysosomes who serves as an antibacterial
• Sclera is a very tough coat Surrounding the eye. Function for protection
• 2 kind receptor cells in the retina:
– Rods = quite sensitive to dim light, but only let you see in black n white
– Cones = give color vision, but only in bright light
• Optic nerve = carry messages to the brain for processing
• Fovea = The part of the retina where the receptor cells are packed most closely together
• Blind Spot = part of the eye the which do not have receptor cells
• Choroid = behind the retinal That is a black layer absorbs all the light after it has been through the retina
• Cornea = is Responsible for most of the bending of the light
• Lens = the make fine adjustment
• 2 kind of muscle in the eyes: suspensory ligaments and ciliary muscle
• Iris = adjust how much Light Enters the Eye
• In the middle of the iris is a space, Called the pupil. The Wider the pupil is, the more light can get through to the retina.
Accommodation = the adjustment in the shape of the lens, to focus light coming from different distances

Coordination

• The part of the body of the which responds to a stimulus is Called an effector. Ex: muscle are effector, if you touch something hot, the contract the muscles in your arm, your hand is so That Quickly Pulled away.
• Most animal (human too) have a central nervous system (Central Nervous System). Central nervous system consists of the Brain (the brain) and Spinal Cord
Sequence of Action – Reaction
Stimulus –> receptors cell –> neuron receptor –> brain –> neuron motor –> effector –> reaction
• Human action can be voluntary or involuntary (motion in humans can be done consciously and unconsciously)

The Endocrine system
Endocrine glands produce hormone. A hormones can be defined as a chemical substance.

A comparison of the nervous and endocrine system in a mammal

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Chapter 3. Enzymes [SHS]

Enzymes are protein molecules which can define as biological catalysts
Catalyst speeds up a chemical reaction, but remain unchanged at the end of the reaction.

Enzyme molecules have an active site.
The active site on an enzyme is a region, usually a cleft or depression, to which another molecule or molecules can bind.

How an enzyme works

All enzymes have certain properties
* All enzymes are protein, but not all protein is enzyme. It’s a functional protein not a structural protein
* Enzymes are catalysts, speeds up a chemical reaction, but remain unchanged at the end of the reaction.
* Enzymes are inactivated by high temperatures, this because they are proteins, which are damaged by temperatures above 40’C
* Enzymes work best at a particular pH, most enzymes work best at a pH about 7, this because they are proteins, which are damaged by very acid or very alkaline conditions
* Enzymes are specific, Each type of enzyme will usually act on only one type of substrate molecule. This is because the shape of the active site will only allow one shape of molecule to fit.

Initial rate of reaction
The rate of enzyme controlled reaction is always fastest at the beginning, because at the beginning there are a large number of substrate molecules.

The rate of the reaction will depend on how many enzyme molecules there are, and the speed at which the enzyme can convert the substrate into product, release it, and bind with another substrate molecule.

Initial rate of a reaction increases linearly with enzyme concentration

Initial rate of a reaction also increases linearly with substrate concentration at the beginning but when the enzyme all occupied then it will reach constant

Enzyme inhibitors
Competitive inhibitors
Inhibitors can bind to active site of the enzyme compete with the substrate. If the inhibitors concentration higher than the substrate then the inhibitors win the competition and inhibit the enzyme work vise versa. It is said to be reversible (not permanent) because it can be reserved by increasing the concentration of the substrate.


Non-competitive irreversible inhibition

The inhibitors can permanently bonded with the active site and therefore cause a permanent block to the substrate. No competition occurs as it does not matter how much substrate is present.

Chapter 3. Enzymes [JHS]

Enzymes are protein molecules which can define as biological catalysts
Catalyst speeds up a chemical reaction, but remain unchanged at the end of the reaction.

Enzyme molecules have an active site.
The active site on an enzyme is a region, usually a cleft or depression, to which another molecule or molecules can bind.

How an enzyme works

All enzymes have certain properties
* All enzymes are protein, but not all protein is enzyme. It’s a functional protein not a structural protein
* Enzymes are catalysts, speeds up a chemical reaction, but remain unchanged at the end of the reaction.
* Enzymes are inactivated by high temperatures, this because they are proteins, which are damaged by temperatures above 40’C
* Enzymes work best at a particular pH, most enzymes work best at a pH about 7, this because they are proteins, which are damaged by very acid or very alkaline conditions
* Enzymes are specific, Each type of enzyme will usually act on only one type of substrate molecule. This is because the shape of the active site will only allow one shape of molecule to fit.

Chapter 16. Humans and the environment

All living things and environment are connected. Example: Humans have an affect to the environment.

Greenhouse Effect
The trapping of heat by a layer of gasses in the earth atmosphere, especially CO2,water vapour and methane. Without this effect, the earth would be too cold to sustain life
Enhanced Greenhouse effect
The amount of CO2 and other greenhouse gases in the atmosphere is getting greater. This may trap more infrared radiation, and make the atmosphere warmer

Gases contributing to the greenhouse effect
– methane
– nitrogen oxides
– CFC
Global Warming
is the increase in the average temperature of Earth’s near-surface air and oceans.
Acid Rain
Rain containing above normal amount of dissolve sulphur oxides and nitrogen oxides
Deforestation
the cutting down of large numbers of trees
Conservation
Maintaining the environment in a state which natural wildlife can flourish

Chapter.15 Living Organism in Their Environment [JHS]

Organism interact with their environment

Ecology is the study of the interaction between living organism and their environments
Habitat is the are where organism lives
Population is a group of organism of the same species
Community is all the organism of all the different species living in the same habitat
Ecosystem is interaction between community with its environment
Niche is the role of an organism in their ecosystem

All living organism need energy, they get energy from food by respiration. All the energy in an ecosystem comes from the sun.

Food chains = representations of the predator-prey relationships between species within an ecosystem or habitat.
Components of food chain:
Producers ex. Green plants
Primary consumers ex. herbivores
Secondary consumers ex. Carnivores
Tertier consumers ex omnivores

Food web = inter-relationship between many food chains

The Water Cycle

Chapter 2. Diffusion, osmosis, and active transport [JHS]

Diffusion can be defined as the net movement of molecules (or ions) from a region of their higher concentration to a region of their lower concentration. The molecules move down a concentration gradient.
Example: CO2 for photosynthesis

Osmosis is the movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.

Animal cells burst in pure water, because water molecules will osmosis into the cell makes the cell swells and the cell getting bigger and bigger and finally will burst

Animal cells shrink in concentrated solutions, because water molecules will osmosis out of the cell makes the cell shrink

Plant cells do not burst in a pure water, because plant cells have a strong cell wall that keeps the cell in shape

Plant cells plasmolyse in concentrated solutions

Active Transport can be defined as the energy consuming transport of molecules or ion across the membrane against a concentration gradient (from a lower concentration to a higher concentration)

Chapter 1. Cells [JHS]

Several characteristic of living organism:
1. They reproduce
2. They take nutrients
3. They respire
4. They Grow
5. They excrete
6. They Move
7. They are sensitive
8. They are made of cells

Cell Structure
All animals and plants are made up of cells. Most cells have:

* A nucleus – controlling the activity of the cell. All cells have these at one point.
* Cytoplasm – where chemical reactions occur. Inside the cytoplasm are enzymes which speed up these reactions. Cytoplasm also contains mitochondria which is where energy is released.
* A cell membrane – to control the passage of substances in and out of the cell.

Plants cells also have

* Cell walls – to strengthen the cell.
* Chloroplasts – to absorb sunlight energy to make food by photosynthesis.
* Vacuole –full of cell sap.

Functions of organelles
1. Cell walls – to strengthen the cell.
2. Cell membrane – to controls what goes in and out of the cells
3. Vacuoles – contain cell sap
4. Chloroplasts – to absorb sunlight energy to make food by photosynthesis
5. Mitochondria – release energy from food
6. Nucleus – stores inherited information

Cells, tissues and organs
Cells act together to form tissues. For instance, the cells on the surface of a leaf form “pallisade tissue”. A group of cells with similar structures and a particular function are called a tissue. Tissues are grouped together to form an organ. A leaf is an organ. Organs are grouped together to form an organism such as a whole plant or animal.

Organelle –> Cells –> Tissue –> Organ –> Organ system –> Organism