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SF LA B1/P1 What you need to know about

Mini revision guide on the foundations of the cells and energy topics for year 9

teaching, science, biology, physics, teaching materials

Cells and Energy

Revision

What you need to know about ...

Plant and Animal Cells

Animal Cells

Plant Cells

Nucleus

Controls the cell's activities and DNA is stored here

Mitochondria

Respiration occurs here

Cell membrane

Controls what enters and leaves the cell

Cytoplasm

A jelly like substance where chemical reactions take place

Mitochondria

Respiration occurs here

Nucleus

Controls the cell's activities and DNA is stored here

Cytoplasm

A jelly like substance where chemical reactions take place

Cell Wall

Gives the cell strength and structure

Chloroplasts

Photosynthesis occurs here

Cell membrane

Controls what enters and leaves the cell

Vacuole

Contains cell sap to keep the cell firm

What you need to know about ...

Specialised Cells

Specialised Cells

A specialised cell is a cell which is suited to do a particular job.

Sperm Cells

A sperm cell is adapted so that it can fertilise an egg cell.

Red Blood Cells

A red blood cell is desgined to carry oxygen around the body.

Nerve Cells

A nerve cell is designed to carry nerve impulses to different parts of the body.

Root Hair Cells

A root hair cell is designed to absorb water and nutrients for a plant.

A tail to allow the sperm to swim towards the egg cell

Lots of mitochondria to release a lot of energy

No nucleus so that they can carry more oxygen

A biconcave (donut) shape so they have a larger surface area to absorb oxygen

A large surface area so that they can absorb water and minerals more effectively

A thin cell membrane to speed up diffusion

Insulation to increase the speed of a nerve impulse

Very long to send nerve impulses up and down the body

What you need to know about ...

Respiration

Aerobic Respiration

Glucose + Oxygen → Carbon dioxide + Water + Energy

Comes from food broken down in digestion

Transported in blood cells from the lungs

Exhaled from the body

More than anaerobic respiration

Respiration happens in the mitochondria

Aerobic Respiration

Glucose→Lactic acid + Energy

Not enough oxygen so glucose can’t be fully broken down

Builds up in

muscles and

causes cramps, needs extra oxygen to break it down

Less than aerobic respiration

Cannot be be used for long periods of time because of this

Fermentation Fermentation is a type of anaerobic respiration by yeast in which glucose is broken down and forms ethanol

Glucose→Carbon dioxide + Ethanol

Can be used to make bread and cakes rise

Can be used in alcoholic drinks

What you need to know about ...

Mitosis

The process of mitosis

Mitosis is a type of cell division in which the cells made are identical to the starting cell

46

92

46

46

The original cell has 46 chromosomes

The chromosomes are copied, so that there are 72 chromosomes

The cell divides in two, with each having 46 chromosomes, each cell is identical to the original cell

Uses of mitosis

Mitosis produces identical cells, it can be used for:

Growth

Replacing dead cells

Asexual reproduction (creating offspring with

only one parent, e.g. in plants)

Where mitosis occurs

Mitosis happens everywhere in the body apart from the sex cells (gametes)

What you need to know about ...

Stem Cells

Stem Cells

Stem cells are undifferentiated cells, they can divide into many other types of cells.

Embryonic Stem Cells

Embryonic stem cells are found in an embryo (developing baby) and can develop into a wide range of other cells.

Adult Stem Cells

Adult stem cells are found in bone marrow, they can divide into other types of cells, but not as many types as embryonic stem cells.

Uses of Stem Cells

Stem Cells can be used for:

Treating Cancers Treating Paralysis Repairing Injuries

Potential growth of Organs

What you need to know about ...

Movement of substances

Diffusion

Diffusion is the random spreading of particles, from an area of high concentration to an area of low concentration. It does not need energy.

Osmosis

Osmosis is the diffusion of water from an area of high concentration to an area of low concentration. It does not need energy.

Active transport

Active transport it the movement of substances from an area of low concentration to an area of high concentration. It requires energy to occur.

High concentration

(all close together)

Low concentration

(spread throughout the liquid)

High concentration of water

(a lot of water molecules)

Low concentration of water

(not a lot of water molecules)

Low concentration

(not a lot of molecules)

High concentration

(a lot of

molecules)

What you need to know about ...

Diffusion In Cells

Diffusion

Diffusion is the random spreading of particles, from an area of high concentration to an area of low concentration.

Factors which will speed up diffusion

High concentration

(all close together)

Low concentration

(spread throughout the liquid)

Diffusion in cells

Diffusion occurs across the cell membrane.

A higher temperature

A gas rather than a liquid

A larger surface area

High concentration of water

(a lot of water molecules)

Low concentration of water

(not a lot of water molecules)

What you need to know about ...

Kinetic Energy

Kinetic Energy

Kinetic energy is the energy of movement, it is measured in joules

Kinetic Energy = 0.5 x mass x speed x speed

(kg) (m/s) (m/s)

Kinetic energy and mass

The greater the mass, the greater the kinetic energy

Example

A car is moving with a speed of 10 m/s and has a mass of 2500 kg. What is the kinetic energy of the car?

Kinetic energy = 0.5 x mass x speed x speed

Kinetic energy = 0.5 x 2500 x 10 x 10

Kinetic energy = 125 000 J

Kinetic energy and mass

The greater the speed, the greater the kinetic energy

What you need to know about ...

Gravitational Potential Energy

Gravitational Potential Energy

Gravitational potential energy is the energy because of the position of an object, it is measured in joules

Gravitational Potential Energy = Mass x Gravity x Height

(kg) (N/kg) (m)

Gravitational Potential energy and mass

The greater the mass, the greater the gravitational potential energy

Example

A book with a mass of 0.25 kg is placed on a shelf with a height of 1.7 m. If the value of gravity on Earth is 9.81 N/kg, what is the gravitational potential energy of the book?

Gravitational potential energy = mass x gravity x height

Gravitational potential energy = 0.25 x 9.81 x 1.7

Gravitational potential energy = 4.17 J

Gravitational Potential energy and gravity

The value of gravity is different on different planets, the greater the value of gravity, the greater the gravitational potential energy

Gravitational Potential energy and height

The greater the height, the greater the gravitational potential energy

What you need to know about ...

Power

Power

Power is a measure of how quickly energy is transferred, it is measured in Watts

Power = Energy ÷ Time

(W) (J) (s)

Factors affecting power

The more powerful an appliance is the faster it will transfer energy

The less time to transfer energy, the more powerful the device will be.

The more time used to transfer energy, the less powerful the device will be.

Example

A light bulb transfers 1000 J of energy in 20 seconds. What is the power of the light bulb?

Power = energy ÷ time

Power = 1000 ÷ 20

Power = 50 W

Power rearrangements

Power = Energy ÷ Time

(W) (J) (s)

Energy = Power x Time

(J) (W) (s)

Time = Energy ÷ Power

(s) (J) (W)

What you need to know about ...

Efficiency

Kinetic Energy

Efficiency is a measure of how much energy is used usefully in a situation, the lower the wasted energy the more efficienct a device is.

Efficiency = (useful energy ÷ total energy) x 100

Increasing efficiency

Efficiency can be increased by reducing wasted energy, examples of how to do this include:

Using lubricants to prevent moving parts rubbing together

For heaters reducing wasted energy to the surroundings by using insulation

Example

A light bulb has 500 J of electrical energy provided to it, if 200 J is transferred as light, what is the efficiency of the light bulb?

Efficiency = (useful energy ÷ total energy) x 100

Efficiency = (200 ÷ 500) x 100

Efficiency = 40 %

Useful and wasted energy

Useful energy is the energy released which is used by the appliance

Wasted energy is any other form of energy given out, usually this can be thermal and sound

Input: Electrical Energy

Useful:

Light Energy

Wasted:

Thermal Energy

What you need to know about ...

Renewable and Non Renewable Energy

Non Renewable energy

Non renewable energy resources will run out, they cannot be replaced within your lifetime

Renewable energy

Renewable energy resources will not run out, they can be replaced within your lifetime

Nuclear power uses radioactive materials to heat water and turn a turbine to generate electricity

Fossil fuels (coal, oil and natural gases) are burned in a power station to heat water and turn a turbine to generate electricity

Wind turbines use the wind to generate electricity

Solar panels convert energy from the sun into electricity

Hydroelectric energy uses falling water to turn turbines and generate electricity

Geothermal uses the heat of rocks to heat water which will turn a turbine to generate electricity

SF LA B1/P1 What you need to know about
Info
Tags Teaching, Science, Biology, Physics, Teaching materials
Type Google Slide
Published 25/11/2020, 18:17:43

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