Inheritance, variation and evolution

What is meant by the term 'cloning' in biology?

Cloning is the process of producing genetically identical individuals.
Clones have exactly the same DNA as the original organism.

What are the 3 main types of cloning covered in GCSE Biology?

• Tissue culture (plant cloning)

• Cuttings (plant cloning)

• Embryo transplants and adult cell cloning (animal cloning)

What is tissue culture in plants, and how is it used?

• Tissue culture involves taking small groups of cells from a plant (often from the roots or shoots).

• These are grown in a sterile nutrient-rich medium with growth hormones.

• The cells grow into identical clones of the original plant.
  ✅ Used to quickly produce many plants from one parent, especially rare or endangered species.

What are the benefits of tissue culture in plants?

• Large numbers of plants produced quickly.

• Can be grown all year round in controlled conditions.

• Allows preservation of rare plants.

• Genetically identical – desirable traits like disease resistance are guaranteed.

How is cloning by cuttings carried out in plants?

• more widely used by gardners one

• A section of a plant (e.g. a stem or leaf) is cut off and planted in soil.

• With rooting hormone and care, the cutting grows into a new, identical plant.
  ✅ Simple, cheap, and can be done by gardeners or farmers.

How are animals cloned using embryo transplants?

• Egg cells from the best cow are artificially fertilised using sperm cells taken from the best bull

• This forms an embryo

• The developing animal embryo is then split apart many times before the cells of the embryo become specialised

• This forms many separate embryos that are genetically identical

• These cloned embryos are then transplanted into host mothers

• The calves born from these host mothers are all genetically identical to each other but not to the host mother

Why are embryo transplants useful in farming?

• Helps produce many genetically identical animals with desirable traits like fast growth or high milk yield.

• Faster than selective breeding alone.

How is adult cell cloning carried out?

• A body cell (e.g. skin cell) is taken from the animal to be cloned.

• The nucleus (which contains the DNA) is removed.

• An egg cell is taken from a female animal, and its nucleus is removed.

• The nucleus from the body cell is inserted into the empty egg cell.

• The egg cell is stimulated with an electric shock to start dividing by mitosis to form an embryo

• The embryo is implanted into the uterus of a surrogate mother.
  ✅ The new animal is a clone of the donor of the body cell.

What famous animal was created using adult cell cloning?

✅ Dolly the sheep was the first mammal cloned from an adult cell in 1996.
She was genetically identical to the sheep that donated the body cell.

What are the potential benefits of cloning?

• Preserving endangered species.

• Farming – produce animals with desirable characteristics so farmers can conistently ensure high quality livestock

• Medical research – study effects of genes and develop treatments.

• Cloning pets or prized animals.

• Tissue culture can help grow plants with specific features.

What are the concerns or problems with cloning?

• Reduced gene pool – less variation, makes species vulnerable to diseases.

• Cloning often fails – embryos may not develop properly.

• Shorter life span – cloned animals sometimes age quickly.

• Ethical concerns – people may begin experimenting in how to clone humans

• Animal welfare – surrogate mothers and clones can suffer.

How does natural cloning differ from artificial cloning?

• Natural cloning occurs in asexual reproduction (e.g. bacteria or plants forming runners).

• Artificial cloning is done by humans through techniques like tissue culture, embryo transplants, or adult cell cloning.

Why is lack of variation in clones a problem?

genetic variation gives a species a better chance of survival against disease or environmental changes so the species can adapt

Clones are genetically identical, so a disease that affects one could wipe out all of them.

Why is the use of antibiotics in farming a concern for antibiotic resistance?

• Antibiotics are used in farming to prevent disease and promote growth in healthy animals.

• This overuse encourages the development of resistant bacteria that can spread to humans through the food chain.

• Bacteria in animals can evolve resistance and pass it on to humans, causing difficult-to-treat infections.

How can we prevent the spread of antibiotic-resistant bacteria?

1⃣ Only use antibiotics when necessary – Avoid over-prescription and use them only for bacterial infections.
2⃣ Complete the full course of antibiotics – Ensure all bacteria are killed and none survive to develop resistance.
3⃣ Good hygiene – Wash hands regularly, especially before eating or after using the bathroom.
4⃣ Infection control in healthcare settings – Sterilize equipment, isolate infected patients, and ensure staff follow hygiene protocols.
5⃣ Educating the public – Raise awareness about the dangers of misuse and overuse of antibiotics.

What is MRSA, and why is it dangerous?

• is a type of bacteria that is resistant to many antibiotics, including methicillin.

• It can cause serious infections, particularly in hospitals or healthcare settings.

• It is harder to treat, leading to longer recovery times and higher risk of complications.

What factors contribute to the spread of antibiotic-resistant bacteria?

• Overuse of antibiotics – Over-prescription of antibiotics, especially when not necessary.

• Misuse of antibiotics – Not completing a full course of treatment, which allows bacteria to survive and evolve.

• Poor hygiene – Not washing hands or sterilizing medical equipment properly.

• Agricultural use – Overuse of antibiotics in farming to promote growth in animals can contribute to resistance.

How do resistant bacteria spread between people?

1⃣ Direct contact – Person-to-person transmission through physical contact.
2⃣ Airborne – Coughing and sneezing can release resistant bacteria into the air.
3⃣ Contaminated surfaces – Bacteria can live on surfaces for hours, leading to indirect transmission.
4⃣ Food and water – Contaminated food or water can carry resistant bacteria.
5⃣ Medical procedures – Poor hygiene during surgeries or injections can spread resistant bacteria.

What could happen if antibiotic resistance continues to increase?

• More deaths from infections that cannot be treated effectively.

• Common surgeries like organ transplants and cancer treatments may become riskier because of infections.

• Increased healthcare costs as hospitals and doctors must use more expensive, less effective antibiotics.

Why is antibiotic resistance a serious problem?

• Limited treatment options – There are fewer effective antibiotics available to treat infections.

• Longer illnesses – Infections that are harder to treat lead to longer recovery times.

• Increased risk of spread – Resistant bacteria can spread to others, making outbreaks harder to control.

• Higher medical costs – More treatments, longer hospital stays, and more intensive care.

How do bacteria become resistant to antibiotics?

1⃣ Random mutation – A small number of bacteria may have a mutation that makes them naturally resistant to an antibiotic.
2⃣ Survival of the fittest – When exposed to the antibiotic, non-resistant bacteria die off, reducing competition for resistant bacteria and so resistant bacteria survive.
3⃣ Reproduction – The resistant bacteria reproduce, passing the resistance to their offspring.

What does antibiotic resistance mean?

• Antibiotic resistance occurs when bacteria evolve to become resistant to drugs that used to kill them.

• As a result, antibiotics become less effective in treating infections caused by these bacteria.

What does extinction mean?

• Extinction occurs when no members of a species remain alive.

• It can happen gradually over time or suddenly due to catastrophic events.

How does extinction relate to evolution?

• Extinction removes species that cannot adapt.

• It allows new species to evolve and fill ecological niches.

• It is a natural part of evolution, but human activity has accelerated extinctions.

What factors can cause extinction?

1⃣ Environmental Changes – Climate change, habitat destruction.
2⃣ New Predators – Invasive species or evolved predators.
3⃣ New Diseases – Bacterial or viral outbreaks.
4⃣ Competition – More successful species outcompete others.
5⃣ Catastrophic Events – Asteroids, supervolcanoes, earthquakes.
6⃣ Human Activity – Pollution, deforestation, hunting.

How does climate change lead to extinction?

• Extreme temperatures – Species may not survive hotter or colder climates.

• Changes in food supply – Plants and prey may die out.

• Rising sea levels – Destroys coastal habitats and islands.

• Extreme weather – More droughts, floods, hurricanes.

How do new predators and competitors cause extinction?

• New predators kill species that lack defenses.

• New competitors outcompete native species for food and shelter.

How do diseases contribute to extinction?

• New diseases can spread rapidly in a species.

• If no individuals are resistant, the entire population dies and is wiped out

How can natural disasters cause mass extinction?

🌋 Supervolcanoes – Ash blocks sunlight, causing a global winter.
☄ Asteroid Impacts – Tsunamis, firestorms, and climate change follow.
🌊 Tsunamis and Earthquakes – Destroy habitats and food sources.

What is a mass extinction?

• A mass extinction is when many species become extinct in a short time.

• It is usually caused by a major environmental change or catastrophic event.

How do human activities lead to species extinction?

• Deforestation – Removes habitats and food sources.

• Pollution – Plastics, chemicals, and oil spills harm wildlife.

• Overfishing and Hunting – Kills species faster than they can reproduce.

• Climate Change – Rising temperatures and extreme weather.

How can we protect endangered species?

✅ Conservation efforts – Protecting habitats and national parks.
✅ Captive breeding programs – Zoos and reserves breed endangered animals.
✅ Laws and regulations – Hunting bans and protection laws.
✅ Reducing climate change – Cutting CO₂ emissions and using renewable energy.

What is a fossil?

• A fossil is the preserved remains or traces of ancient organisms.

• They are found in rocks and provide evidence of life from millions of years ago.

Why do scientists study fossils?

✅ Evidence for evolution – Show how species have changed over time.
✅ Reconstruct ancient environments – Reveal past climates and ecosystems.
✅ Track extinction events – Help understand mass extinctions.

What are the three ways fossils can form?

1⃣ Mineral Replacement (Hard Parts Fossils) – Bones, shells, and teeth are replaced by minerals, turning them into rock-like structures.

2⃣ Casts and Impressions – Organisms leave behind moulds or imprints in soft material, which hardens over time.
3⃣ Preservation in Special Conditions – Some organisms are trapped in amber, ice, or peat bogs, preventing decay.

How does mineral replacement create fossils?

1⃣ Organism dies and is buried quickly by sediment (e.g., sand, mud).
2⃣ Soft tissues decay, leaving only hard parts (bones, teeth).
3⃣ Water rich in minerals seeps in, gradually replacing organic material with minerals.
4⃣ Over millions of years, the fossil forms inside rock layers.

How impressions fossils form?

• Impressions – Footprints, leaves, or shells press into soft mud, which later hardens into rock.

What conditions prevent decay and preserve fossils?

❄ Ice/Permafrost – Freezing temperatures prevent bacteria from decomposing the body.
💦 Peat Bogs – Lack of oxygen stops microbes from breaking down the body.

What is the fossil record, and why is it important?

• The fossil record is the collection of all known fossils.

• It helps scientists understand how life evolved and identify extinct species.

Why are there gaps in the fossil record?

❌ Not all organisms fossilize – Soft-bodied organisms decompose before they fossilize.
❌ Fossils can be destroyed – By earthquakes, erosion, or volcanic activity. ( geological activity)
❌ Fossils are difficult to find – Some remain undiscovered deep underground.

How do fossils provide evidence of extinction events?

• Fossils show remains of species that no longer exist (e.g., dinosaurs).

• Large gaps in the fossil record indicate mass extinctions (e.g., asteroid impact 65 million years ago).

What evidence do fossils provide for evolution?

✅ Fossils show gradual changes – older fossils show less complex organisms and younger fossils show more complex organisms showing progression of species
✅ Common ancestors – Similarities in fossils suggest all species share a common ancestor.
✅ Extinct species – Fossils reveal species that have disappeared due to natural selection.

What is variation in biology?

• Variation refers to differences between individuals of the same species.

• It can be due to genetic or environmental factors, or a combination of both.

What are the types of variation?

1⃣ Genetic Variation – Differences caused by genes.
2⃣ Environmental Variation – Differences caused by surroundings.
3⃣ Combined Variation – Most traits result from both genetics and environment.

What are the three causes of genetic variation?

✅ Mutations – Random changes in DNA.
✅ Sexual reproduction – Offspring inherit a mix of alleles from both parents.
✅ Meiosis – Gametes (sperm & egg) are genetically different due to crossing over

What are some examples of traits caused by genetic variation?

✅ Eye color
✅ Hair color
✅ Blood group (A, B, AB, O)
✅ Natural resistance to diseases

• These traits are determined by genes and cannot be changed by the environment.

What are some environmental factors that cause variation?

✅ Diet – A person's height or weight may be influenced by nutrition.
✅ Climate – Sun exposure affects skin color.
✅ Exercise – Affects muscle growth and fitness levels.
✅ Lifestyle choices – Can impact health and development.

What are some examples of traits caused by environmental variation?

✅ Scars
✅ Tattoos
✅ Language spoken
✅ Weight (affected by diet and exercise)

• These traits are not inherited and are influenced by external factors.

What characteristics result from a combination of genetic and environmental variation?

✅ Height – Influenced by genes and diet.
✅ Weight – Affected by metabolism (genetic) and diet/exercise (environmental).
✅ Intelligence – Influenced by genetics and education/life experiences.
✅ Skin color – Genetic but affected by sun exposure.

• Most physical and behavioral traits result from a combination of both genetic and environmental factors.

What is continuous variation, and what are some examples?

• Continuous variation shows a range of values with no distinct categories.

• It is controlled by multiple genes (polygenic) and often influenced by the environment.

Examples:
✅ Height
✅ Weight
✅ Skin color

What is discontinuous variation, and what are some examples?

• Discontinuous variation has distinct categories with no in-between values.

• It is controlled by a single gene or a few genes (monogenic) and not affected by the environment.

Examples:
✅ Blood group (A, B, AB, O)
✅ Eye color
✅ Tongue rolling ability

What is a mutation, and how does it cause variation?

• A mutation is a random change in DNA that can introduce new alleles.

• Mutations can be beneficial, harmful, or neutral.

Examples:
✅ Beneficial mutation – Sickle cell trait provides resistance to malaria.
✅ Harmful mutation – Cystic fibrosis affects lung function.
✅ Neutral mutation – No effect on survival (e.g., attached or free earlobes).

How does variation contribute to evolution?

• Variation provides differences in traits within a species.

• If the environment changes, some individuals may be better adapted.

• Those with advantageous traits survive and reproduce (natural selection).

• Over time, this leads to evolution and the development of new species.

Example:
✅ Peppered moths – Dark-colored moths became more common in polluted areas due to better camouflage.

Why is genetic variation important for the survival of a species?

✅ Prevents extinction – If all organisms were identical, a disease could wipe out the entire species.
✅ Allows adaptation – Species can evolve in response to environmental changes.
✅ Ensures diversity – Leads to a healthier and more resilient population.

How does selective breeding affect variation?

• Selective breeding involves choosing parents with desirable traits to breed.

• This reduces genetic variation due to reduced gene pool and can lead to health problems due to inbreeding.

How does genetic engineering create new variation?

• Scientists can insert new genes into an organism’s DNA.

• This introduces new traits that do not occur naturally.

• Example: Golden rice is genetically modified to contain vitamin A.

How do human activities affect variation in organisms? Give 4 ways

✅ Selective breeding – Reduces variation by choosing specific traits.
✅ Genetic engineering – Introduces new traits artificially.
✅ Deforestation & habitat destruction – Reduces variation by wiping out species.
✅ Pollution & climate change – Forces species to adapt or go extinct.

What is genetic modification (genetic engineering)?

Genetic modification (GM) is the process of altering an organism’s DNA by inserting genes from another organism.

What are the main steps of genetic engineering?

1. Identify the desired gene from another organism

2. Cut out the gene using restriction enzymes (special enzymes that cut DNA at specific sites).

3. Insert the gene into a vector (a plasmid or virus).

4. Insert the vector into the target organism (e.g., bacteria, plants, or animals).

5. The organism expresses the new gene, producing the desired trait

What is a vector, and what are the types used in genetic engineering?

• A vector is a carrier that transfers genes into another organism.

• Common vectors:

  • Plasmids (small circular DNA in bacteria).

  • Viruses (used to insert genes into animal or plant cells)

How is genetic engineering used in medicine?

• Producing human insulin – GM bacteria can be used to produce insulin for diabetes treatment.
  ✅ Gene therapy – Faulty genes in humans can be replaced to cure diseases.
  ✅ Producing vaccines – GM organisms can be used to develop safer and more effective vaccines.

How is genetic engineering used in agriculture?

GM crops – Crops can be modified to:

• Be resistant to pests (e.g., Bt corn, which produces its own pesticide).

• Be resistant to herbicides (allows farmers to kill weeds without harming crops).

• Have improved nutrition (e.g., Golden Rice with added vitamin A).

• be drought resistant

What are genetically modified (GM) crops?

GM crops are plants that have had genes artificially inserted to improve their properties.

How is genetic engineering used in animals?

• Farm animals – GM animals can grow faster or produce healthier meat.
  ✅ Disease resistance – Some GM animals are resistant to infections.
  ✅ Medical research – GM mice are used to study human diseases.

• Chickens that produce more eggs

What are the benefits of genetic modification?

Increases crop yields – Helps feed growing populations.
✅ Reduces pesticide and herbicides use – GM crops can resist pests naturally and less use of herbicides so better biodiversity
✅ Improves human health – Produces medicines like insulin.
✅ Prevents genetic diseases – Used in gene therapy to cure disorders.

What are the risks and ethical issues of genetic modification?

Unknown long-term effects – GM organisms may have unexpected consequences.
❌ Possible harm to ecosystems – Modified genes may spread to wild plants/animals. ( eg. gene for herbicide resistance may spread to weeds making them resillient to herbicides)
❌ Ethical concerns – Some believe it is unnatural to modify DNA.
❌ GM crops can be expensive – Farmers in poorer countries may not afford them and so no one will buy their crops and they’ll become even poorer

at what stage in life must gene therapy be done

when the person is young or an embryo so that as they grow all of their cells posses the healthy gene if done when the person is older they’ll have to replace the faulty gene in every single cell

What are inherited disorders?

Inherited disorders are genetic conditions caused by faulty alleles that can be passed from parents to offspring through genes.

• Some disorders are caused by dominant alleles, while others are caused by recessive alleles.

What is cystic fibrosis, and how is it inherited?

Cystic fibrosis (CF) is a recessive genetic disorder that affects the lungs and digestive system by producing thick, sticky mucus.

What is polydactyly, and how is it inherited?

• Polydactyly is a disorder that causes a person to have extra fingers or toes. ( however this can easily be removed through surgery)

• It is caused by a dominant allele (P), meaning only one copy is needed for the disorder to be present.

What is embryonic screening?

Embryonic screening is a process used to test embryos for genetic disorders before implantation or birth.

What are the two types of genetic screening?

1. Pre-implantation Genetic Diagnosis (PGD)

• Used in IVF before implantation.

• Only healthy embryos are implanted into the mother.

2. Prenatal Testing (Amniocentesis & CVS)

• Used to test for genetic conditions in a developing fetus.

• Amniocentesis – Sample of amniotic fluid taken at 15-20 weeks of pregnancy. ( risky as can cause a miscarriage)

What are the advantages of embryonic screening?

1. gives mum a choice

2. reduction in the prevalence of a disease in a population

3. saves NHS money as treatment and research of genetic disorders is expensive

4. can avoid sufferring by stopping children being born with genetic disorders

5. there are laws in place to stop embryo screening being abused so that parents don’t choose embryos with desirable trait

What are the disadvantages and ethical concerns of embryonic screening?

1. the process implies that people with genetic disorders are undesirable

2. it’s very expensive and therefore not accessible to everyone

3. Could lead to ‘designer babies’ – Risk of choosing babies with desirable traits

What is gene therapy?

Gene therapy is a technique that replaces faulty genes with healthy ones to treat genetic disorders.

What are the advantages of gene therapy?

Potential cure for genetic diseases – Unlike medicines, it fixes the problem at the source.
Could save lives – Helps patients with fatal conditions.
Reduces symptoms – Improves quality of life for patients with disorders like cystic fibrosis.

What are the disadvantages of gene therapy?

1. many believe that gene alteration is unnatural

2. Expensive – Not widely available.

3. Unpredictable long-term effects – The inserted gene may not work properly as it’s still relatively experimental

What is evolution?

• Evolution is the gradual change in species over time.

• It happens because of natural selection.

• Over generations, species develop new traits that help them survive.

natural selection is the process by which ______ happens

evolution

How does natural selection cause evolution?

1⃣ Variation – Organisms in a species have different traits (caused by mutations).
2⃣ Competition – Organisms compete for limited resources (food, mates, shelter).
3⃣ Survival of the fittest – The best-adapted individuals survive/ individuals with advantageous traits
4⃣ Reproduction – Survivors pass their beneficial genes to offspring.
5⃣ Gradual Change – Over time, the species evolves.

what is a species

group of organisms that can interbreed and produce fertile offspring

What evidence do scientists have for evolution?

✅ Fossil record – Shows how species have changed over millions of years.
✅ DNA evidence – Similar DNA between species shows common ancestry.
✅ Comparative anatomy – Similar bone structures in different animals.
✅ Antibiotic resistance – Bacteria evolve to survive antibiotics.

What did Charles Darwin propose?

Species evolved over time from simple life forms because of variation and survival of the fittest.

Why was Darwin’s theory not widely accepted at first?

❌ It contradicted religious beliefs about creation.
❌ There was not enough evidence at the time (fossils and DNA were not well understood).
❌ Genetics were not yet discovered, so he couldn’t explain how traits were inherited.

What is speciation?

Speciation is the process by which new species form.

What are the steps in speciation?

1⃣ Isolation – A population is separated (e.g., by a river, mountains, or climate change).
2⃣ Different Environments – Each group adapts to its new surroundings.
3⃣ Natural Selection – Different traits become favorable in each group.
4⃣ Genetic Differences – Over time, changes accumulate, and the groups become too different to interbreed.
5⃣ New Species Formed – They can no longer reproduce together.

Why do bacteria show rapid evolution?

• Bacteria reproduce very quickly.

• Mutations can make some resistant to antibiotics.

• These bacteria survive and reproduce, leading to antibiotic-resistant strains (e.g., MRSA).

Who was Gregor Mendel, and what did he discover?

• He experimented with pea plants and discovered inheritance patterns.

• He found that characteristics are passed on in predictable ways.

Mendel’s Key Discoveries:
✅ Genes exist in pairs (now called alleles).
✅ Some traits are dominant, others are recessive.
✅ Traits are inherited from parents.

Why was Mendel’s work not understood at the time?

❌ He was a monk, not a famous scientist.
❌ DNA and genes were not discovered yet.

His ideas were later confirmed when chromosomes and DNA were discovered.

What is selective breeding?

• Selective breeding (artificial selection) is when humans choose specific organisms with desirable traits to breed.

• Over generations, this enhances certain traits in a species.

What are the steps in selective breeding?

1⃣ Choose parents with the desired characteristics.
2⃣ Breed them together.
3⃣ Select the best offspring with the desired traits.
4⃣ Repeat the process for multiple generations until the trait is prevalent.

How do farmers use selective breeding?

• Increases crop yield – Wheat plants with larger grains are bred.

• Disease resistance – Crops that are naturally resistant to pests are selected.

• Better meat production – Chickens that grow faster are bred for farming.

How is selective breeding used in livestock?

• Cows bred for higher milk production.

• Chickens bred to lay more eggs.

• Sheep with softer wool.

• Dogs bred for specific traits (e.g., guide dogs for temperament, greyhounds for speed).

What are the benefits of selective breeding?

✅ Higher yields – More food production.
✅ Better quality products – Improved milk, meat, or fruit.
✅ Disease resistance – Reduces crop failure.
✅ Desirable traits – Animals with better temperament or appearance.

What are the risks of selective breeding?

❌ Reduces genetic variation – Leads to inbreeding.
❌ Increases risk of genetic disorders due to reduced gene pool – Health problems in purebred animals.
❌ Less resistance to new diseases – If a disease affects one, it may kill many.
❌ Ethical concerns – Some breeds suffer from health issues (e.g., pugs with breathing problems).

What is inbreeding, and why is it a problem?

• Inbreeding happens when closely related individuals breed.

• Reduces genetic diversity, leading to:
  ✅ Higher risk of genetic disorders (e.g., hip dysplasia in dogs).
  ✅ Lower ability to adapt to environmental changes.
  ✅ Increased susceptibility to diseases.

How does selective breeding compare to genetic engineering?

	Selective Breeding	Genetic Engineering
Method	Chooses existing traits	Directly alters DNA
Speed	Takes generations	Can be done quickly
Precision	Less precise	More precise
New Traits?	No new traits, only enhances existing ones	Can introduce entirely new traits

Example: Golden Rice (genetically engineered for vitamin A) vs. Drought-resistant wheat (selectively

Why do some people oppose selective breeding?

• Animal welfare – Some breeds have serious health issues (e.g., bulldogs with breathing problems).

• Loss of genetic diversity – Reduced variation can harm ecosystems.

• Overuse of resources – Breeding only high-yield crops can deplete soil nutrients.

natural selection vs artificial selection

Feature	Natural Selection 🌿	Artificial Selection (Selective Breeding) 🧬

Definition

The process where organisms with beneficial traits survive and reproduce.

The process where humans select organisms with desirable traits to breed.

Speed

Slow process – Takes many generations for significant change.

Faster process – Humans can enhance traits in a few generations.

Genetic Diversity

Maintains genetic variation, which is important for species survival.

Reduces genetic variation, which can lead to inbreeding and health issues.

Adaptation

Produces better-adapted organisms for survival in the wild.

Produces organisms suited to human needs, not necessarily survival.

Outcome

Leads to evolution over time and can result in new species.

Leads to improved traits but does not create new species.

one is determined by nature and one is determined by humans

What is Sexual Reproduction?

Sexual reproduction involves the fusion of gametes (sperm and egg in animals, pollen and egg in plants).