Science - Term 2 + 2nd half Flashcards
Chemical energy
Energy that is stored in food, fuel and batteries.
Kinetic energy
Energy stored in moving objects
Thermal energy
Energy stored in hot objects.
Stain energy or elastic potential energy
Energy stored in stretch, quashed or twisted materials.
Gravitational potential energy
Energy stored in objects in position.
Atomic energy or Nuclear energy
Energy stored inside atoms.
System
Something in which we are studying changes .
Law of conservation of energy
Energy cannot be created or destroyed. It can only be transferred from one store to another.
Joules (J)
Unit for measuring energy.
Energy diagrams
They represent energy stores and transfers using diagrams.
Sankey diagram
It shows the amount of energy transferred. The width of the arrows represents the amount of energy in joules.
Dissipated
Spread out
What happens to energy that is dissipated?
This energy cannot be used for other useful energy transfers - it is wasted.
How do most machines waste energy?
Most machines waste energy when they get hot. Whenever two moving parts touch each other, friction causes them to heat up. The thermal energy stored in the machine is transferred to the surroundings by heating, which dissipates the energy. This energy is wasted.
What does Lubrication do?
Friction between moving parts can be reduced by lubrication.
Examples of lubricants
- Oil
- Other liquids
- Even gases
Efficiency
A way of describing how good a machine is at transferring energy into useful forms.
How is efficiency measured?
It is given a number between o and 1. 0 means that all the energy transferred is wasted. 1 means all the energy transferred is useful energy (no devices are ever this effective).
Energy efficiency formula
(Useful energy transferred by the device)
___________________________________________
(Total energy supplied to the device)
= Efficiency
Sea waves transfer energy to the…
… shore.
What type of waves are waves on the surface of water?
Transverse waves
What type of wave are sound waves?
Longitudinal waves
Examples of seismic waves
Earthquakes and Explosions
Electromagnetic waves
Transverse waves
Do not need a medium to travel through
Wave frequency
The number of waves passing a point each second.
Measured in hertz.
Period
The length of time it takes one wave to pass a given point.
Wavelenght
The distance from a point on one wave to a point in the same position on the next wave, measured in metres.
Amplitude
The maximum distance of a point on the wave away from its rest position, measured in metres. The greater the amplitude of a sound wave, the louder the sound.
Velocity
The speed of the wave in the direction it is travelling. Waves travel at different speeds in different materials.
How do you measure wave amplitude?
The amplitude of a wave is from the middle of the top or bottom of two waves not the distance between top of one wave and the bottom of another.
Speed formula with measurements
Speed(m/s) = Distance (m) / time (s)
Wave speed formula
wave speed (m/s) = frequency (Hz) x wavelength (m)
How doe we hear step 1?
Sound waves enter the ear canal.
How do we hear step 2?
- The ear drum is a thin membrane. sound waves make it vibrate.
How do we hear step 3?
- Vibrations are passed on to tiny bones which amplify the vibrations (make them bigger).
How do we hear step 4?
Vibrations are passed on to the liquid inside the cochlea.
How do we hear step 5?
Tiny hairs inside the cochlea detect these vibrations and create electrical signals called impulses.
How do we hear step 6?
Impulses travel along neurons in the auditory nerve to reach the brain.
Cochlea
The cochlea is a coiled tube containing liquid. It can detect the different frequencies of sound reaching the ear.
Ultrasound
Sound made by waves with higher frequencies than this.
Infrasound
Sounds with a frequency less than 20Hz are too low for humans to hear.
Ray diagrams
A way of modelling what happens when light is reflected or refracted.
Law of reflection
When waves are reflected, the angle of reflection is equal to the angle of incidence.
The normal line
This is the line drawn at a right angle to the barrier or mirror.
Incident ray
A ray of light that strikes a surface
Reflected ray
Light ray that bounce off a surface.
Refraction
The bending of light (it also happens with sound, water and other waves) as it passes from one transparent substance into another.
Angle of refraction
The angle between a refracted ray and the normal drawn at the point of incidence to the interface at which refraction occurs.
Iterface
Boundary
Total internal reflection
The complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium.
Critical angle
The angle of incidence when the angle of refraction is 90o, and the ray changes from just refracting to total internal reflection.
Diffuse reflection
The reflection of light from a surface such that an incident ray is reflected at many angles, rather than at just one angle.
Visible spectrum
The segment of the electromagnetic spectrum that the human eye can view.
White light
Electromagnetic radiation of all the frequencies in the visible range of the spectrum, appearing white to the eye.
Electromagnetic wave
A form of radiation that travel though the universe.
Ultraviolet
We cannot see ultraviolet (UV) light but it can have hazardous effects on the human body. Ultraviolet light in sunlight can cause the skin to tan or burn. Fluorescent substances are used in energy-efficient lamps - they absorb ultraviolet light produced inside the lamp, and re-emit the energy as visible light. Similar substances are used on bank notes to detect forgeries. The hazardous properties of UV mean it will kill bacteria and can be used for disinfecting water.
Infrared
Infrared radiation (IR), sometimes referred to simply as infrared, is a region of the electromagnetic radiation spectrum where wavelengths range from about 700 nanometres (nm) to 1 millimetre (mm). Infrared waves are longer than visible light waves but shorter than radio waves.
Celebellum
Responsible for muscle coordination and movement.
* It is found at the back of the brain * Responsible for... ○ Muscle co-ordination Balance
Cerebral cortex
Outer layer of neural tissue.
Responsible for consciousness, memory, intelligence and language.
Pituitary gland
Master gland, responsible for regulating many body functions, controlling the activity of other glands.
Medulla
Controls unconscious activities, like breathing and heart rate.
Spinal cord
Carries information between the brain and the rest of the body.
Medulla oblongata
Controls your heart and breathing rate
cerebrum
- the largest part of the brain
- It is split into left and right cerebral hemispheres, they control the muscles in the opposite halves of the body E.g. The left cerebral hemisphere control muscles on the right half of your body
- Different parts of the cerebrum are responsible for different things including
○ Movement
○ Language
○ Vision
○ Memory
Intelligence
Function of the brain
- Part of the central nervous system
Made up of billions of interconnected neurones with the purpose of sending electrical impulses down the relay neurones
Investigation the brain - CT scanner
- Use x-rays to produce images of the brain, so
○ You can look at the structure but not the seen their functions- CTs can show damaged or diseased parts of the brain so if the patient has lost a function you know it is related to that part E.g. If the area at the back of the brain is damaged and the patient cannot see then that part of the brain is related to vision
Investigation the brain - PET scanner
- For PET scanners, you are injected with a radioactive chemical called tracer. The tracer moves around the body and collects in different areas, the more active cells take up more tracer than less active cells. When the person is inside the tracer we can see where the tracer builds up.
○ So you can see which parts of the brain are currently active- PET scanners investigate both structure and function at the same time
- PET scan can show areas of the brain that are active or inactive, so we can study these changes
E.g. Alzheimer’s disease is a brain disorder. The mains symptom is memory loss and if we look at where the patient has less activity in certain areas compared to a normal brain. We can discover where in the brain the problem lies
Why is it difficult to treat problems in the central nervous system?
- It is hard to repair damaged parts of the nervous system because neurones there do not readily repair themselves and scientists have not discovered ways to repair them
- It is hard to access parts of the brain E.g. We cannot surgically remove tumours in certain parts of the brain
The treatment may cause further damage that may or may not be permanent.
- It is hard to access parts of the brain E.g. We cannot surgically remove tumours in certain parts of the brain
What is included in the CNA?
The neurons and the brain
Impulse
The nervous system sends messages through out the body as electrical signals.
Neurotransmission
A travelling impulse and happens in the neurones.
Explain the pathway of a nerve impulse
- Stimulus
- Impulse starts at receptor.
- Impulse passed along sensory neurone.
- Impulse passed along motor neurone.
- Effector(muscle) receives impulse to react.
- Response
The nervous system
A system that allows you to recognise to a stimuli in the surrounding and co-ordinate a response or behavioural change.
Stimuli
A changes in the environment and to survive the change organisms must respond to these stimuli.
Single cell organism
One cell in an organism
Multicellular organism
Several cells in the organism
Sensory receptors
Sensory receptors are groups of cells that detect stimuli and initiate a response.
Examples of sensory receptors
Eyelids->detect light
Skin->detect pressure, touch, tissue damage, temperature
Cornea
The transparent outer layer at the front of the eye. It refracts light into the eye.
Lens
It retracts light, focusing it onto the retina.
Pupil
The hole in the centre of the eye, through which light enters.
Iris
It contains muscles that allow it to control the diameter of the pupil and therefor how much light enters the eye.
Retina
The layer at the back of the eye that contains 2 types of receptor cells (cones and rods)
Cones
Sensitive to light intensity.
Rods
Sensitive to colour.
Ciliary muscles and suspensor ligaments
It control the shape of the lenses.
What happens to people who are long sighted?
○ This occurs when…
§ the eyeball is to short
§ The lens is the wrong shape
§ The lens does not refract the light enough
To correct this you can wear glasses or contact lenses with a convex lens (lenses that curve outwards)
What happens to people who are short sighted?
○ This occurs when…
§ the eyeball is to long
§ The lens is the wrong shape
§ The lens refract the light too much
○ To correct this you can wear glasses or contact lenses with a concave lens (lenses that curve inwards)
Long-sighted
Cannot focus on nearby objects.
Short sighted
Cannot focus on distant objects.
Colour blindness
When you cannot tell the difference between two colours.
What happens when people are colour blind?
Cataract
A blurry patch on the eye that stops light from entering the eye.
What happens when people have cataract issues?
○ People with cataract have
§ Blurred vision
§ Colours are less vivid
Have difficulty seeing bright lights
Advantages of sexual reproduction
- There only needs to be one parent so they can reproduce in any favourable condition without having to wait for a mate.
- The reproductive cycle is faster than sexual reproduction so you can produce more offspring quickly and colonise a new area
Disadvantages of asexual reproduction
- There is no variation between offspring when created through asexual reproduction so if the environment changes and the conditions become unfavourable the entire population will not be able to cope.
- Less chance of adapting to new conditions
Advantages of sexual reproduction
- There is variation between offspring when created through sexual reproduction
Short term: population is less likely to get wiped out by a single event
Long term : Population is likely to adapt to changing conditions. This allows for evolution to take place.- Most favourable traits are most likely to survive
Species change over time
- Most favourable traits are most likely to survive
Disadvantages of sexual repoduction
- Time
- The reproductive cycle is slower than asexual reproduction so you can produce less offspring.
There needs to be two parent so they are dependent on a mate.
- The reproductive cycle is slower than asexual reproduction so you can produce less offspring.
- Energy
- To impress mate
Sexual reproduction
- 2 parent (M+F)-meiosis
- Gametes - specialised cell
- Sperm
- Egg
- Genetically different offspring.
Less likely to all have the same genetic problems
Haploid
Half the number of chromosomes
A sexual reproduction
- 1 parent - mitosis
- No gametes
- Clone - look the same
They both have same generic diseases
Diploid
Full set of chromosomes
Clones
Look the same
Hermaphrodite
Both sexual organs
Body cells and chromosomes
- Most cell structures have a nucleus that contains genetic material that is stored in chromosomes
- Body cells normally have two copies of each chromosome (diploid)
One from mother’s gamete and one from father’s gamete
- Body cells normally have two copies of each chromosome (diploid)
Cell cycle
A process where body cells in multicellular organisms divide to produce new cells.
Mitosis
When a cell reproduces itself splitting into two to form two genetically identical offspring (specifically focusing on the division of the nucleus)
Cytokinesis
- The division of the cytoplasm that takes place at the same time as mitosis.
- When before telophase ends, the cytoplasm and cell membrane divide to form two separate cells daughter cells.
Interphase
- In a cell that is not dividing, the DNA is all spread out in long strings
- Before it divides, the cell has to grow and increase the amount of subcellular structures
- It then duplicates its DNA so there are 2 copies of each chromosome for each new cell. The replicated DNA stay attached to the original to form and X-shape. An arm(chromatid) is an exact copy of the other.
Phases of Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase
The chromosomes condense getting shorter and fatter and the nuclear membrane breaks down so the chromosomes lie free in the cytoplasm.
Metaphase
The chromosomes line up along the centre of the cell and the spindle fibres attach to them.
Anaphase
The spindle fibres pull the chromosome apart and the chromatids are pulled to opposite ends of the cell.
Telophase
Membranes form around each set of chromosomes to form a nucleus.
Uses of mitosis
- Growth
- Replacing damaged cells
- Asexual reproduction
How to calculate the number of cells produced?
Number of cells = 2^n
n=number of cell divisions
Tumours
Cells replicating by mitosis all the time.
Benign
A bunch of cells that grow abnormally and then stop.
Malignant
A bunch of cells that keep replicating and invading other areas.
Metastasis
A bunch of cells that start appearing somewhere else.
Rick factors of getting cancer
- UV lights
- Carcinogens
- Genetics
Sexual reproduction
When genetic information from a male and female gametes are combined to produce an offspring which is genetically different to either parent.
Fertilisation
- The fusion of the male and female gametes.
- When a male gamete fuses with a female gamete (produce a zygote for humans).
Gametes
A haploid that is produced by meiosis.
E.g. Egg (Female gamete) and sperm (male gamete) for animals.
Haploid
Gametes that contain half the number of chromosomes in a normal cell(so one copy of each chromosome)
Diploid
Gametes that have two copies of each chromosome.
Zygote
A fertilized egg that ends up with the full number of chromosomes.
* The zygote turns into an embryo through mitosis.
Genome
The entire set of DNA instructions found in a cell.
DNA
The instructions for an organism are found as code in a molecule.
Meisosis
A type of cell division which produces non-identical, haploid cells. It takes place in reproductive organs.
Maternal chromosomes = mother
Paternal chromosomes = father.
Steps for cell division by meiosis
- Before a cell starts to divide. It duplicates its genetic information(forming two identically armed chromosomes)
- Then the chromosomes arrange themselves into pairs
- In the first division the chromosomes line themselves up along the centre of the cell
- The pairs are then pulled apart to each new cell only has one copy of each chromosome. Some of the fathers and some of the mothers go into that cell.
#the mixing up of parents chromosomes is really important as it mixes up their genes, creating genetic variation in the offspring - The chromosomes line up along the centre of the cell and the spindle fibres attach to them
- The spindle fibres pull the chromosome apart and the chromatids are pulled to opposite ends of the cell
You get four genetically different, haploid, daughter cells (these are gametes)
Steps to hearing
- Vibrations in the air pass down the ear canal.
- This causes vibrations in the ear drum.
- These vibrations are passed on to the tiny ear bones.
- These amplify and transmit them to the cochlea.
- This contains a long coiled up membrane inside a tube containing a fluid.
- Vibrations in the fluid make the membrane move.
- Vibration in the membrane are detected the hair cells (receptors) generate an impulse.
- Impulses are sent to the brain.
- Some of the energy transferred through the air is transferred to the ear drum.
- The changes in pressure at the surface of a solid cause vibrations.
- The air pressure changes as the sound wave travels.
- A sound wave causes the particles in the air to move.
- The vibrations in the particles in the solid are longitudinal.
Sound waves
- Sound waves = longitudinal
○ Therefor particles in a gas move backwards and forwards as a sound wave passes
○ When a sound wave reaches a solid, some energy is transferred is reflected and some is absorbed of transmitted
○ Sound waves cause pressure on the surface of the solid causing it to vibrate and the disturbance is passed from the air to solid. These vibrations can be passed as transverse and longitudinal
How the cochlea works?
- Coiled tube containing a liquid detects the different frequencies of sound reaching the ear(from 20Hz to 20 000Hz)
- The parts of the membrane that vibrates depends on the frequencies as different thickness of membranes vibrate best at different frequencies
- The thousands of hair cells along the membrane detect its vibrations
- Each hair cell is connected to a different neurone that sends impulses to the brain
- The brain interprets neurones from different neurones as different pitches of sound.
Energy
The ability of an object (or living thing) to do work, to perform an action.
Types of energy stores
- Gravitational potential energy stores
- Kinetic energy stores
- Elastic energy stores
- Chemical energy stores
- Thermal energy stores
- Nuclear energy stores
Useful forms of energy
- Electricity
- Waves
○ Light
○ Sound
○ Microwaves
○ X-rays
- Waves
Examples of energy stores and transfers
A ball being kicked along the ground = chemical -> kinetic + (thermal) + (sound)
Car climbing a hill = Chemical ->kinetic ->gravitational potential + (thermal)
A battery-operated motor = Chemical -> kinetic + (thermal)
Hydroelectric power station = Gravitational potential -> kinetic -> electrical + (thermal)
A chocolate bar being eaten = Chemical -> kinetic + (sound) + thermal
A kettle = ?->thermal + (sound)
Sankey diagrams
The diagram shows how much of the input energy is transferred into useful output as well as how much is wasted.
Transverse waves
The movement (wave) is perpendicular (at 90 degrees) to the direction of travel.
Longitudinal waves
The movement is parallel to the direction of travel of the wave.
Electromagnetic waves
§ They do not need a material particles to travel through.
§ They transmit energy through force fields
§ E.g.
□ Light waves
□ Radio waves
□ Microwaves
