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Genes

Every living organism is made from cells. most cells have a nucleus. inside the nucleus are chromosomes. chromosomes are made from very long molecules of DNA. chromosomes contain thousands of genes (which parents pass on to offspring in their sex cells during reproduction) . Genes are instructions that control how a living thing develops and functions. Genes control which proteins a cell makes including:

Structural proteins to build the body i.e. collagen

functional proteins to take part in chemical reactions i.e. enzymes such as amylase

your characteristics depend on your genes and the environment

some depend on one gene only i.e dimples

some depend on several genes working together i.e eye colour

some depend on the environment only i.e. scars

some depend on genes and the environment i.e weight

Environmental factors include:

climate

diet

physical accidents

culture

lifestyle

For example, an individual might inherit a tendency to tallness, but a poor diet during childhood will result in poor growth and a shorter individual.

Variation is the differences between living things of the same species.There are two kinds of variation continuous and discontinuous.

continuous variation has no limit. some examples of continuous variation are:

height

weight

heart rate

leaf length

some examples of discontinuous variation are:

tongue rolling

finger prints

eye colour

blood groups

Inheritance

Human body cells each contain 23 pairs of chromosomes. Parents pass on their genes to their offspring in their sex cells.

Human cells (except sex cells) contain pairs of chromosomes. One chromosome in each pair came from the mother’s egg and the other from the father’s sperm.

female sex cells are called egg cells, or ova

male sex cells are called sperm

The chromosomes in a pair carry the same genes in the same places. however the two genes in a pair can be different. different versions of the same gene are called alleles. for each gene a person has either two identical alleles or two different alleles.

if both alleles for a gene are the same you are homozygous for that gene.

if both alleles are different you are heterozygous.

Sex cells only contain one chromosome from each pair. When an egg cell and sperm cell join together, the fertilised egg cell contains 23 pairs of chromosomes. One chromosome in each pair comes from the mother, the other from the father.

you have similarities to your parents because you developed from a fertilised egg that got alleles from your mother and father

Sex Chromosomes

Humans have one pair of sex chromosomes in each body cell. Female humans have two X chromosomes (XX). males have one X chromosome and one Y chromosome (XY).

the chromosomes in sex cells do not pair up. every egg has an X chromosome. Half of all sperm have an X chromosome the other sperm have a Y chromosome. The Y chromosome includes a sex-determining gene. this makes an embryo develop testes and so become male. when there is no Y chromosome the embryo developed ovaries. it is female.

Why are we different?

Brothers and sisters are not identical. this is because they inherit different combinations of alleles from their parents.

alleles can be dominant or recessive.

A recessive allele only shows if the individual has two copies of it. For example, the allele for blue eyes is recessive. You need two copies of this allele to have blue eyes.

A dominant allele always shows, even if the individual only has one copy of it. For example, the allele for brown eyes is dominant. You only need one copy of it to have brown eyes. Two copies will still give you brown eyes.

A description of your genes is called your genotype.

your phenotype is a description of your characteristics.

Inherited disorders

Some disorders are caused by inheriting faulty alleles of just one gene.

Cystic Fibrosis

Cystic Fibrosis is caused by a faulty recessive allele (f).

You need to inherit two copies of the faulty allele (one from each parent) to be born with Cystic Fibrosis. If you have just one copy, you are a carrier, but will not experience any symptoms.

Carriers do not have the disorder but can pass it onto their children i.e.

Children with Cystic Fibrosis produce a thick and sticky mucus in their lungs and airways. they have:

difficulty breathing

difficulty digesting food

Frequent chest infections

As a result, they are more likely to get respiratory infections.

Huntington's Disease

Huntington's disease develops after the age of 35. it is fatal.

Huntington’s disease is caused by one faulty dominant allele (H). you can inherit Huntington’s disorder if one or both of your parents carry the faulty allele, because it is a dominant allele.

The symptom include:

tremor and clumsiness

memory loss and concentration problems

modd changes

Genetic testing

Genetic testing involves analysis of a person’s DNA to see if they carry alleles that cause genetic disorders (they detect faulty alleles). It can be done at any stage in a person’s life.

Reasons for having the test include:

For an adult to find out if they are a carrier of a genetic disorder

For an adult to find out if they will develop symptoms of a genetic disorder

For a pregnant women to find out if her fetus has a genetic disorder

to find out how a person might react to a prescription drug

to find out if embryos created outside the body have faulty alleles and so choose which to implant in the uterus. this is pre-implantation genetic diagnosis.

However there are issues to consider like:

should a carrier have children?

Should the adult tell relatives who may also develop symptoms?

should they have an abortion if the test is positive?

will removing cells for the test increase the risk of a miscarriage?

should a different drug be used?

does removing a cell damage the embryo?

is it ethically right to destroy embryos?

Some examples of Genetic testing is:

Pre-implantation Genetic testing

Carrier testing

Neonatal Testing

Limits of Genetic testing

Genetic tests are not available for every possible inherited disorder. And they are not completely reliable. They may produce false positive or false negative results, which can have serious consequences.

False positives wrongly show that a person will develop a disorder.

False negatives wrongly show that a person will not develop a disorder

Asexual reproduction

Asexual reproduction needs only one parent, unlike sexual reproduction, which needs two parents

As a result, the offspring are genetically identical to the parent and to each other. They are clones.

Bacteria, plants such as bulbs and runners and some animals like starfish can reproduce asexually to from clones.

Cloning

clones are individuals with identical genes. only environmental factors can cause differences between clones. identical twins are clones they form when the cells of an embryo separate to make two embryos.

scientists make clones by nuclear transfer, the steps are:

the nucleus is removed from an unfertilised egg cell and discarded

the nucleus is removed from an adult body cell (of the organism they want to clone) and injected into the egg cell

an electric shock is applied to make the egg cell begin to divide to form an embryo

while it is still a ball of cells, the embryo is inserted into the womb/uterus of an adult female

the embryo continues to grow and develop

Stem cells

Stem cells are unspecialised cells. there are two types:

Embryonic stem cells which can develop into any type of cell

Adult stem cells which can develop into many but not all types of cell

most stem cells become specialised during the early development of a living organism. Because they are unspecialised stem cells may be useful in future to treat some illnesses.

Disease and resistance

The body’s first line of defence against harmful pathogens is the skin and stomach acid, the second is white blood cells. Inside your body, conditions are ideal for microorganisms like bacteria and viruses. So they reproduce quickly. some bacteria and viruses cause infectious diseases. they give you disease symptoms damaging cells or making poisons (toxins).

Pathogens

Pathogens are microorganisms that cause infectious disease. Bacteria and viruses are the main pathogens.

Bacteria

Bacteria come in many shapes and sizes, but even the largest are only ten micrometres long. Bacteria are living cells and can multiply rapidly in favourable conditions. Once inside the body, they release poisons or toxins that can make us feel ill.

Viruses

Viruses are many times smaller than bacteria. They are among the smallest organisms known, consisting of a fragment of genetic material inside a protective protein coat.

Viruses can only reproduce inside host cells, damaging them when they do so. Once inside, they take over the cell and make hundreds of thousands of copies of themselves. Eventually, the virus copies fill the whole host cell and it bursts open. The viruses then pass out through the bloodstream, the airways, or by other routes.

Population growth of microorganisms

In the correct conditions (with warmth, moisture, nutrients) bacteria can multiply rapidly. The human body can provide these conditions for bacteria to multiply, for example in a cut. Each bacterium splits into two up to every 20 minutes.

Lines of Defence

When microorganisms enter the body, they release toxins. The toxins damage cells to cause the symptoms of the disease. The body’s first line of defence is its natural barriers which include:

skin

chemicals in tears

chemicals in sweat

stomach acid

White blood cells

The body’s first line of defence is called passive immunity, which means preventing the pathogen from entering in the first place. If a pathogen manages to get into the body, the second line of defence takes over, which is called active immunity this involves white blood cells.

White blood cells try to destroy harmful microorganisms. they are part of your immune system.

White blood cells can:

engulf pathogens and destroy them

produce antibodies to destroy pathogens

produce antitoxins that neutralise the toxins released by pathogens.

Once microorganism get inside your body your while blood cells begin to respond

By Producing Antibodies

- Antigens/markers are found on the surface of the microorganisms.

- White blood cells recognise the foreign antigens and produce antibodies.

- The antibodies lock onto the antigens.

- This makes the microorganisms clump together so other white blood cells can digest them

using phagocytosis.

By Phagocytosis

- The microorganisms invade the body

- The white blood cell finds the microorganisms and engulfs them.

- The cell engulfs the microorganisms

- The microorganisms have been digested and destroyed.

By producing antitoxins

The antitoxins neutralise the toxins released by pathogens.

The two main groups of white blood cells are Phagocytes and lymphocytes

Memory cells

Some of the white blood cells that make each antibody stay in your blood these are memory cells. if the same microorganism invades your body in future memory cells recognise its antigens. the memory cells quickly make the correct antibodies. the invaders are destroyed before you feel ill. you are immune to the disease.

Mutation Rate

On average an adult human will catch two to four colds every year, and a child will catch even more (because their immune system is still developing. This happens for two main reasons:

there are hundreds of different cold viruses

the viruses have a high mutation rate

A high mutation rate means that the DNA of the virus frequently changes, so the human body has to destroy the virus using a different antibody each time, which makes it harder to develop immunity.

Vaccines

Vaccination involves exposing the body’s immune system to a weakened or harmless version of the pathogen in order to stimulate white blood cells to produce antibodies

Vaccines prevent you from getting diseases. a vaccine contains a safe form of a disease-causing microorganism. when a vaccine is injected into your body white blood cells make antibodies against the microorganism. your body stores some of these memory cells so if an active form of the microorganism enters your blood in future memory cells quickly make antibodies. you do not get ill.

However having vaccinations isn't risk free. different people have different side effects because they have different gene.

to prevent the world-wide spread of infectious diseases a hight percentage of the population must be vaccinated. if they are not large numbers of the disease causing microorganism will remain in infected people and people who cannot be vaccinated are likely to catch the disease.The more infectious the disease, the higher the proportion of the population that must be vaccinated

Some common diseases like influenza (flu) and the common cold are caused by viruses. These mutate quickly, and this changes their surface proteins. This makes it almost impossible to develop a permanent vaccine against them.

Antibiotics

Antibiotics are substances that kill or prevent the growth of bacteria and fungi. They do not work against viruses. It is difficult to develop drugs that kill viruses without damaging the body’s tissues.

Overtime some bacteria and fungi become resistant to antimicrobials. This is an example of natural selection. Antimicrobial resistance develops when mutations in the genes of bacteria and fungi make new varieties that the antimicrobial cannot kill. Mutations in bacteria can result in them becoming resistant to antibiotics, turning the bacteria into a superbug. Superbugs can develop while a person is taking a course of antibiotics.

To reduce antibiotic resistance people must:

finish all the tablets even if they feel better

only use antibiotics when necessary

Drug testing

New medical drugs have to be tested to ensure that they work, and are safe, before they can be prescribed. there are three main stages of testing:

The drugs are tested using computer models and human cells grown in the laboratory.

Drugs that pass the first stage are tested on animals.

Drugs that have passed animal tests are used in clinical trials on humans.

It is important that the results of clinical trials are not influenced by the people involved. So volunteers are put into two groups at random and checks are done to make sure both groups have a similar gender balance and age range.

So there are three types of human trails:

in Double-Blind trials, neither the patients and doctors know who is in which group. This removes the chance of bias and makes the results more reliable

in a Blind trail, the patients don't know which group they are in but the doctors do.The problem is the doctors may give away clues to the patients without realising it.

in an Open-Label trial both the patient and the doctor knows whether the patient is given the new drug. this trial is used when the patient cannot affect the outcome.

long term human trials ensure that the drug is safe and that it works. they also identify side-effects that do not occur immediately

Placebos

A placebo looks like the new treatment but has no drugs in it. placebos are rarely used in human trials because people who take them miss out on the benefits of both new and existing treatments.

The Heart

Blood carries oxygen and nutrients to the body’s cells, and waste products away from them. The circulatory system consists of:

the heart, which is the muscular pump that keeps the blood moving

the arteries, which carry blood away from the heart

the veins, which return blood to the heart

the capillaries, which are tiny blood vessels that are close to the body’s cells.

How does the heart work?

Your heart pumps blood around your body. it is a double pump:

the right lower chamber pumps blood to your lungs

the left lower chamber pumps blood to the rest of your body

Your heart is made from muscle. it has its own blood supply in order to keep beating. the blood brings oxygen and glucose to the heart. the heart cells use these as a supply of energy. Blood travels around your body through arteries, veins and capillaries. blood vessels are well adapted to their functions.

Arteries take blood from the heart to your body. Their walls withstand the high pressure created by the pumping heart. The arteries have:

thick outer walls

thick layers of muscle and elastic fibres

Viens push blood back to the heart. they have thin walls that can be squashed when you move. the veins have:

thin walls

thin layers of muscle and elastic fibres

Unlike arteries veins have one-way valves in them to keep the blood moving in the correct direction.

Capillaries take blood to and from tissues. Their very thin walls allow oxygen and food to diffuse into cells and waste diffuse out of cells. Capillaries have:

thin walls that are only one cell thick

Doctors can check how well your heart is working. They measure:

Pulse Rate, usually taken on the inside of your wrist. This measures the number of beats per minute.

Blood Pressure, this measures the pressure of the blood on the walls of your arteries. it has two numbers 140 and 90. the higher number is the pressure when the heart is contracting. the lower number is the pressure when the heart is relaxing. Height, weight, gender and lifestyle affect blood pressure.

High blood pressure is the biggest concern as it increases the risk of a heart attack.

Heart disease

The muscle cells in the heart need a constant supply of oxygen and nutrients. they also need their waste products to be removed. So the heart requires its own blood supply in order to keep beating.

The blood vessels called the coronary arteries carry oxygenated blood to the heart.If they become blocked, a heart attack can happen.

Heart attack

Heart attacks can happen after a sequence of events:

fatty deposits build up in the coronary arteries

a blood clot can form on a fatty deposit

the blood clot can block a coronary artery

the blockage stops heart muscle cells getting the oxygen and nutrients they need

these cells start to die and the heart is permanently damaged

Factors for heart disease

Your genes and your lifestyle affect your chances of having a heart attack.

The risk of developing heart disease is increased by:

smoking

high blood pressure

poor diet (high levels of salt and saturated fats)

stress

misuse of dugs i.e alcohol

High levels of salt in the diet can lead to increased blood pressure. High levels of saturated fats in the diet lead to a build of cholesterol in the arteries, causing a plaque and narrowing of the arteries.

Vision defects

short-sight

someone who is short-sighted can see near objects clearly, but can't focus properly on distant objects.

long-sight

someone who is long-sighted can see distant objects clearly, but can't focus properly on near objects.

Homeostasis

Automatic control systems keep body conditions constant. they are controlled by nervous and hormonal communication systems. keeping a constant internal environment is called homeostasis.

Cells in the body need certain conditions to work properly. Homeostasis is how the body keeps internal conditions the same. Two examples of things that the body keeps the same are:

body temperature at 37°C

the amount of water inside our body.

body control systems have:

receptors to detect changes in the environment

processing centres to receive information and coordinate a response

effectors to produce a response

they use negative feedback between the effector and the receptor of a control system to reverse changes and to return to the systems steady state.

For example, negative feedback keeps our body temperature at a constant 37°C. If we get too hot, blood vessels in our skin become larger and we lose heat and cool down. If we get too cold blood vessels in our skin become smaller, we lose less heat and our body warms up. Negative feedback also controls:

blood oxygen levels

salt leves

Water Balance

Cells only work properly if their water content is maintained at the correct level

the kidneys maintain our body's water balance by controlling the water levels in blood plasma. The kidneys also control salt levels and waste products like the excretion of urine.

Water levels in your blood plasma may go down because of:

sweating after exercise or on a hot day

eating salty food

not drinking much water

The kidneys maintain our water balance by producing urine of different concentrations.when water levels in blood plasma are low, your kidneys make less urine. the urine is concentrated (dark). when water levels in blood plasma are high your kidneys make lots of dilute urine.

ADH

The concentration of our urine is controlled by a hormone called ADH.

The kidneys are part of a negative feedback system.

Receptors in the brain detect changes in concentration in blood plasma.

if the concentration is too high the pituitary gland in the brain releases ADH into the bloodstream

The ADH travels to the kidneys (effectors). the more ADH that arrives the more water the kidneys reabsorb into the body so the more concentrated the urine.

When the blood plasma is more dilute, less ADH is released into the bloodstream. This allows more water to leave the kidneys, producing more dilute urine.

Drugs affect the amount of urine you make.

Alcohol leads to big volumes of dilute urine so you may get dehydrated. this is because alcohol stops the pituitary gland releasing ADH

taking Ecstasy leads to small volumes of concentrated urine. this is because ecstasy makes the pituitary gland release more ADH. it can result in the body having too much water.

Definition of Species

A species is a group of organisms that can breed together to produce fertile offspring.

Living organisms have features that help them survive in their environment. They can do this because they have adapted to their environment. Adaptations increase a species’ chance of survival making it more likely that individuals will survive and reproduce.

Food Webs

Within an organisms habitat there is competition for resources. Animal species may compete for food or shelter. plants compete for space and light.

Species in a habitat rely on each other and on their environment for food and other needs. the species are interdependent. A food web shows what eats what in a habitat.

changes to the food web affect other species.

For Example:

If the Fox population decreases, the population of mice, slugs, beetles and frogs will increase. Badger numbers may also increase because there are fewer foxes to compete with.

Therefore any change in any environment can have knock-on effects

The Sun

Energy from the sun is the source of energy for nearly all life on Earth. Plants (producers) absorb a small percentage of light energy from the sun during photosynthesis. the light energy is stored by converting it to chemicals which make up plant cells.

Animals Bacteria and Fungi depend on plants for food. so nearly all life is dependant on energy from the sun.

Energy Transfer

Energy is transferred between organisms:

when animals (consumers) eat other organisms or

when Decomposers and Detritivores eat dead organisms and waste materials

however only a small percentage of the energy at each level of the food chain is passed on. the rest of the energy:

is used for life processes i.e. moving and keeping warm

escapes to the surroundings as heat

is excreted as waste and passed on to decomposers

cannot be eaten and is passed on to decomposers

because so much energy passes out of the food chain, food chains usually have no than four species.

An example of energy flow through an ecosystem is shown below

If we want the percentage efficiency of energy transfer between producers and primary consumers:

Efficiency = energy available to the next stage / energy that was available to the previous stage * 100

Carbon Cycle

Plants take Carbon Dioxide out of the atmosphere by photosynthesis. In photosynthesis plants convert the carbon from Carbon Dioxide into sugars i.e. Glucose.

Eating passes the carbon in the plants along to animals in a food chain or web. Both animals and plants break down glucose in respiration. this returns carbon dioxide back into the atmosphere.

plants and animals eventually die and decompose. microorganisms break down the molecules of dead organisms by decomposition this relates Carbon Dioxide back into the atmosphere.

The combustion of fossil fuels adds Carbon Dioxide to the atmosphere.

Nitrogen Cycle

Nitrogen just like carbon is constantly being recycled.

The atmosphere contains 78% Nitrogen gas. Both plants and animals need nitrogen to make proteins for growth but nitrogen directly from the air is very unreactive and so it can't be used by plants or animals. Plants are able to take up nitrogen compounds such as nitrates to make proteins from the soil. Animals can only get proteins by eating plants or each other.

Nitrogen fixation is the process of turning Nitrogen from the air into Nitrogen compounds i.e. Nitrates. There are two ways that this happens:

Lightning, the energy in a lightning bolt is enough to make nitrogen react with oxygen in the air to give nitrates

Nitrogen fixing bacteria, in roots and soil

Decomposers break down proteins in dead plants and animals into ammonia. Ammonia is turned into nitrates by nitrifying bacteria that are found in the soil. Denitrifying bacteria break down the nitrates in the soil and release nitrogen to the air. This is denitrification.

Monitoring the environment

scientists use indicators to measure environmental change. For example:

Non-living indicators

Temperature of an environment will vary, over a long period of time it could indicate that the climate of the environment is changing i.e. Global Warming. we use a thermometer to measure the temperature.

Nitrate Levels in streams, rivers and lakes, an increase in nitrate level could be caused by fertilisers entering the water which could show that the water is being polluted.

Carbon Dioxide levels in air and oceans, an increase in CO2 could be caused by human activities such as burning fossil fuels. Increases in CO2 increase the rate of Global Warming.

Living indicators

Lichens to monitor air quality, they are very sensitive to the levels of sulfur dioxide and so can give ideas about the level of pollution from car exhausts and power stations. The number and type of Lichen in a particular location will indicate how clean the area is i.e. the area is clean if there are lots of lichen

Mayfly Nymphs to monitor oxygen levels in rivers, if raw sewage is released into a river, the bacterial population in the water increases and uses up the oxygen. Nymphs are good living indicators for water pollution. if you find Nymphs in a river its means the water is clean.

Phytoplankton (algae) to measure ocean temperature changes, populations increase when the levels of nitrates in the water increase this is called an algal bloom. adding fertilisers or sewage to rivers and lakes causes an increase in nitrates so algal blooms can be used to indicate water pollution.

Evolution

Life on Earth began about 3500 million years ago. All species evolved from simple living things. Life then evolved to become more complex and varied. Fossil records and DNA both provide evidence for evolution:

Fossil records show how species are getting more and more complex as time goes on

DNA controls the characteristics of living things, it also mutates and changes over time. All living things have some similarities in their DNA, the more closely related two species are the more similar their DNA. scientists can use the similarities and differences in DNA to work out how life has evolved.

There is variation between individuals of a species. Genetic variation is caused by mutations. Mutated genes can be passed on to offspring, this produces new characteristics. Overtime this makes species change and the process of evolution can produce new species.

causes of evolution:

Natural Selection works on the new characteristics so that if they are of benefit they spread through each of the populations.

Environmental changes i.e. if the climate changes in one area but not another then organisms of the same species will develop different adaptations to the different conditions they live in

Isolation, sometimes groups of organisms of the same species become isolated from each other so they cant interbreed.

Charles Darwin

Darwin developed the theory of evolution by natural selection, which he came up with by making many observations of organisms and applying creative thought to his findings.

Lamarck argued that if the characteristics was used a lot by an animal then it would become more developed. Lamarck reckoned that these acquired characteristics could be passed on to the animals offspring. however Lamarck’s theory was rejected.

Darwin’s theory is a better scientific explanation than Lamarck’s as it fits with modern genetics and is supported by more evidence.

Selective breeding

Selective breeding is where humans choose what gets selected.

It involves humans deliberately choosing a feature they want to appear in the next generation and only breeding from animals or plants that have it. This is different form natural selection as it doesn't promote features to help survival

Natural Selection ‘Survival Of The Fittest’

Natural selection is the process that causes evolution.

Living things show genetic variation

The resources living things need to survive are limited. Individuals must compete for these resources to survive. only some individuals will survive.

Some of the varieties of a particular species will have batter chance of survival. Those varieties will then have an increased chance of reproducing and passing on their genes.

This means the next generation will have characteristics that help the organisms to survive.

overtime the species become better and better so they can survive. The best features are naturally selected and the species become more adapted to its environment.

Biodiversity

Sustainability means meeting the needs of people today without damaging the Earth for people in future.

Biodiversity includes:

The number of different species on Earth

The range of different types of organisms i.e. microorganisms plants and animals

The genetic variation between organisms of the same species

Maintaining Biodiversity is important because:

The more plants we have available the more resources there are for developing new food crops

We use plant substances as medicines

Extinction

If all the members of a species die out the species is extinct. The rate of extinction of species is increasing because:

there are changes in the environment to which a species cannot adapt

a new species arrives that eats, competes with or causes disease of the species.

another species in its food web becomes extinct

humans can also cause extinction by hunting or destroying an organisms habitat

Classification

There is a huge variety of life on Earth. Living organisms include plants animals and microorganisms. Within each of these groups there are millions of species and within each species there is a much genetic variation.

So scientists use the similarities and differences of organisms’ physical features and DNA to put them into groups this is called classification

All of the species on Earth can be grouped into five kingdoms:

bacteria

fungi

algae

plants

animals

Each kingdom is then divided into more groups. As you go down a group the number of types of organisms decrease and the characteristics that the organisms have increase.

Classification is useful because:

It shows the evolutionary relationships between different organisms

It helps make sense of the diversity of life

Sustainability

Sustainability means meeting the needs of todays populations without harming the environment so that the future generations can still meet their own needs.

Human activities can damage the environment i.e. pollution and some of the damage we do can't be repaired i.e. destruction of rainforests. this means the environment wont be the same for future generations.

We are also placing greater pressure on our planets limited resources i.e. we use fossil fuels but they will eventually run out this means that the resources wont be around for future generations

Planning

Maintaining biodiversity is an important part of sustainability. Loss of biodiversity means that future generations wont be able to get the things from the environment that we can today i.e. the extinction of some species could mean a reduction in our ability to produce food or find new medicines.

Packaging

Packaging materials are usually thrown away this isn't sustainable because this isn't sustainable because:

the production and transport of packaging uses huge amounts of energy i.e. burning fossil fuels damages the environment

Packaging creates lots of waste, in landfill sites this waste takes up a lot of space and damages the environment

Biodegradable packaging often fails to decompose in landfill sites because there is not enough oxygen

the resources that have gone into making the packaging material isn't reused so they're no longer available to future generations

The sustainability of using packaging materials can be improved by:

using renewable materials a lot of packaging materials come from non-renewable resources i.e. plastic is made from oil. using materials from like paper and card from trees can improve sustainability as the resources can be replaced by planting more trees

using less energy making packaging from recycled materials uses less energy than producing new materials. this means the environment isn't damaged as much

Creating less pollution most plastics aren't biodegradable this means they cant be broken down naturally by microorganisms so they will pollute the land. using biodegradable materials i.e. wood is more sustainable

The most sustainable thing to do is to use less packaging material.