IB biology study guide for quiz ( A 4.1.1 - D4.1.1)

what is the definition of evolution

Evolution is the change in the heritable characteristics of a population over time.

What did Lamarck propose about evolution?

Lamarck proposed use and disuse and inheritance of acquired characteristics.

What is “use and disuse” in Lamarckism?

Frequently used structures strengthen; unused structures deteriorate.

What is “inheritance of acquired characteristics”?

Traits gained during an organism’s lifetime are passed to offspring.

Why is Lamarckism rejected today?

Because somatic changes cannot be inherited; only germline changes are passed on.

What is Darwinian evolution?

Evolution occurs through natural selection acting on heritable variation.

( only the heritable characteristics are passed on and the only ones that count for evolution)

Key difference between Lamarck and Darwin?

Lamarck: acquired traits are inherited.

Darwin: only heritable genetic variation is inherited.

Why was Darwin’s theory a paradigm shift?

It replaced Lamarck’s mechanism with a new, evidence‑based explanation: natural selection.

What is a paradigm shift?

A fundamental change in scientific understanding.

What is natural selection?

A process where individuals with heritable traits that improve survival/reproduction leave more offspring, causing those traits to increase in frequency.

What ecological observations did Darwin make?

1. Populations can increase exponentially.

2. Populations remain stable at certain sizes.

3. Resources are limited.

What inference follows from Darwin’s ecological observations?

Not all offspring survive; there is a struggle for resources.

What heredity observations did Darwin make?

1. Individuals vary in many characteristics.

2. Many characteristics are heritable.

. What inference follows from Darwin’s heredity observations?

Some individuals survive and reproduce more because of heritable traits.

What is Darwin’s final inference (natural selection)?

Differences in survival/reproduction are not random; beneficial traits increase over generations → the population evolves.

How long has natural selection operated?

Natural selection has operated continuously since the formation of the first cells, producing Earth’s biodiversity.

What is LUCA?

The Last Universal Common Ancestor, from which all modern cells descend.

Why is natural selection an example of inductive reasoning?

It uses specific observations → pattern recognition → general conclusion.

. Why is natural selection considered a scientific theory?

It is repeatedly tested, corroborated, explains many observations, and is unlikely to be falsified.

How does natural selection fit the correspondence theory of truth?

It is true because it accurately describes the way the world is.

How does natural selection fit the coherence theory of truth?

It fits coherently within a larger, consistent body of scientific knowledge.