The preserved remains or traces of an organism that lived long ago, usually found in rock.

How do fossils provide evidence for evolution?

They show what organisms were like in the past and how their features changed gradually over very long periods of time.

Explain how a population of bacteria becomes resistant to an antibiotic.

A random mutation makes a few bacteria resistant, the antibiotic kills the rest, and the survivors reproduce until most of the population is resistant.

Why is antibiotic resistance in bacteria such strong evidence for evolution?

It is natural selection happening fast enough to be watched and measured directly.

OCR GCSE Combined Science Biology J250

Cell Level Systems

Topic overview Microscopy, and sub-cellular structures DNA structure: polymer, double helix and nucleotides Enzyme action, and investigating enzymes Cellular respiration as an exothermic process Aerobic and anaerobic respiration compared Synthesis and breakdown of carbohydrates, proteins and lipids Photosynthesis: producers and the process Photosynthesis as endothermic, and investigating it Limiting factors in photosynthesis

Community Level Systems

Topic overview Cycling materials, and the role of microorganisms The carbon and water cycles, and decomposition Levels of organisation, and abiotic and biotic factors Interdependence, competition, mutualism and parasitism

Genes, Inheritance and Selection

Topic overview Genetic terms, and the genome Genome, environment and mutations Haploid, diploid and meiosis Single gene inheritance and Punnett squares Sex determination and characteristics controlled by many genes Variation within a population, and classification Natural selection and evolution Evidence for evolution from fossils and antibiotic resistance

Global Challenges

Topic overview Field investigations, and human impact on ecosystems Maintaining biodiversity, monitoring conservation and ecotourism Selective breeding and genetic engineering Health, disease, and types of disease Interactions between diseases, and how they spread Reducing the spread of disease, and named examples White blood cells, antibodies and platelets Non-specific defences and the immune system Vaccines, medicines and aseptic technique Developing new medicines, and non-communicable disease Treating cardiovascular disease, and lifestyle factors Cancer, and the use of stem cells in medicine Gene technology in medicine, and the human genome

Organism Level Systems

Topic overview The nervous system and coordinated responses The reflex arc Hormonal coordination, thyroxine and adrenaline Hormones in reproduction and the menstrual cycle Contraception and treating infertility Homeostasis and control systems in the body Insulin and glucagon in blood sugar control Type 1 and type 2 diabetes

Scaling Up

Topic overview Diffusion, osmosis and active transport Mitosis, the cell cycle and cell differentiation Stem cells in animals and meristems in plants Surface area to volume ratio and exchange surfaces The circulatory system, the heart and blood vessels Red blood cells and plasma Root hair cells, transpiration and translocation Xylem and phloem Factors affecting water uptake, and the potometer

Genes, Inheritance and Selection

Evidence for evolution from fossils and antibiotic resistance

3 things to know
Paper 8 (Biology)

Overview

Fossils and antibiotic resistance as evidence for evolution, why the fossil record is incomplete, how bacteria become resistant to an antibiotic and why they evolve so quickly, and why stopping a course of antibiotics early helps resistance spread.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Give two lines of evidence for evolution.

Key term

What is a fossil?

Key term

Why is the fossil record incomplete?

Questions from this subtopic

Each one with the model answer underneath.

1
Give two lines of evidence for evolution.
Model answer
Fossils, and the development of antibiotic resistance in bacteria.
2
What is a fossil?
Model answer
The preserved remains or traces of an organism that lived long ago, usually found in rock.
3
How do fossils provide evidence for evolution?
Model answer
They show what organisms were like in the past and how their features changed gradually over very long periods of time.
4
Why is the fossil record incomplete?
Model answer
Many organisms have soft bodies that decay instead of fossilising, and many fossils that did form have been destroyed or have not yet been found.
5
Explain how a population of bacteria becomes resistant to an antibiotic.
Model answer
A random mutation makes a few bacteria resistant, the antibiotic kills the rest, and the survivors reproduce until most of the population is resistant.
6
Why is antibiotic resistance in bacteria such strong evidence for evolution?
Model answer
It is natural selection happening fast enough to be watched and measured directly.

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Cell Level Systems

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Genes, Inheritance and Selection

Global Challenges

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AA diet high in sugar and fat leads to obesity.

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