The Revision Village App is LIVE for learning on-the-go! For iOS and Android

IB

Answers toStudent Questions

AllIB MathematicsIB SciencesIB Individuals & Societies

Psychology

What is an MRI in psychology?

Magnetic Resonance Imaging (MRI) is a brain imaging technique that uses strong magnetic fields, radio waves, and a computer to produce detailed 2D or 3D images of brain structure, which can then be analysed by a trained professional. This method allows researchers to explore how differences or changes in brain structure may be linked to changes in behaviour, and vice versa. One strength of MRI is that it is safe and non-invasive, allowing repeated scans to be conducted without exposing participants to harmful radiation. This makes it useful for studying long-term changes in the brain. However, a limitation is that MRI only provides structural information, not data about brain activity. It is also expensive and requires participants to remain very still during the scan, which can be challenging for certain groups and may limit its accessibility in some research contexts. In psychology, researchers use MRI to study how the brain develops from childhood to adulthood, helping them understand typical brain maturation and how it relates to behaviour and cognitive abilities. MRI is also used to show neuroplasticity, revealing how the brain physically changes in response to learning and experience.

Environmental Systems and Societies

What is one major cause of species extinction?

Extinctions occur due to changes in a species’ habitat, natural disasters, or direct human actions aimed at the species. Humans are currently driving the **sixth mass extinction** through various factors: - Habitat destruction - Climate change - Introduction of non-native species - Hunting and overharvesting of wild species - Pollution The scale of environmental change and species loss we have caused over the past few centuries has led some scientists to propose naming a new geological epoch: the **Anthropocene**. The **first five mass extinctions** were triggered by natural events such as: - Meteorite impacts - Changes in sea level - Super-volcanic eruptions - Climate change - Tectonic plate movements A key difference between these events and the current mass extinction is the speed. While past extinctions occurred over thousands to millions of years, the current one is unfolding at an accelerated pace due to human activity. It’s important to recognize that extinctions are a natural part of life. As species evolve, they may shift into new niches or change their habitat, leading to the extinction of other species. This, in turn, creates opportunities for new species to evolve and fill the vacated niches. This roughly steady rate of extinction is known as the **background extinction rate**. However, the current extinction rate, driven by human actions, is estimated to be 100 to 10,000 times higher than the natural background rate.

Physics

What determines gravitational pull?

Gravitational pull, otherwise known as the force of gravity, acts between all objects due to their mass. Around any individual mass there exists a gravitational field that will cause any other mass placed within it to be attracted to the original mass. The gravitational field strength is represented by the symbol $g$ and has units of N kg$^{-1}$. The gravitational pull on an object depends on its mass m and the strength of the gravitational field that it is in. The formula for the gravitational force $F_g$ is $\hspace{3em} F_g = mg$ The gravitational pull between two masses can also be found using Newton’s Universal Law of Gravitation. This law shows that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to their separation distance. $\hspace{3em} F_g = G\dfrac{m_1m_2}{r^2}$ Where: $\hspace{2em}F_g$ is the force of gravity in units of N \ $\hspace{2em}G$ is the gravitational constant 6.67 x 10$^{-11}$ N m$^2$ kg$^{-1}$\ $\hspace{2em}m_1$ and $m_2$ are the masses of the two objects in units of kg\ $\hspace{2em}r$ is the separation of their centres of mass in units of m

Economics

What are non-price determinants in economics?

In microeconomics, the price of a product has the most significant effect on consumer behaviour (demand) and producer behaviour (supply). However, many other factors affect the quantities demanded and supplied at every price. For example, consumers will pay a higher price for products they prefer. Hence, if consumer preference for a product increases, consumers will demand more at each price. The demand schedule below shows consumer preferences before and after an advertising campaign. Assuming the advertising campaign is successful—it increases consumer preference for the good—quantity demanded increases at every price. |Price |Quantity demanded$_1$|Quantity demanded$_2$| |:-:|:-:|:-:| |$0|200|250| |$10|150|200| |$20|100|150| |$30|50|100| |$40|0|50| Economists call this change an increase in demand. An increase in demand differs from an increase in *quantity demanded*, which occurs when the price decreases. An increase in demand is shown by a rightward shift of the demand curve; a decrease in demand is shown by a leftward shift of the demand curve. The table below shows how the determinants and how they impact demand: |Non-price determinant of demand|Demand shifts right if…|Demand shifts left if…| |:-:|:-:|:-:| |Tastes and preferences|consumers want a product more|consumers want a product less| |Price of related goods (substitutes)|price of other goods increases|price of other goods decreases| |Price of related goods (complements)|price of other goods decreases|price of other goods increases| |Income (normal goods)|incomes increase|incomes decrease| |Income (inferior goods)|incomes decrease|incomes increase| |Future expectations of price|prices are expected to rise|prices are expected to fall| |Number of consumers|consumers join market|consumers leave market| Similarly, when factors other than price change producer preference, supply increases (the supply curve shifts right) or decreases (the supply curve shifts left). |Non-price determinant of supply |Supply shifts right if…|Supply shifts left if…| |:-:|:-:|:-:| |Cost of raw materials/labour|costs decrease|costs increase| |Price of related goods (joint supply)|price of other goods increases|price of other goods decreases| |Price of related goods (competitive supply)|price of other goods decreases|price of other goods increases| |Taxes and subsidies|indirect taxes decrease/subsidies increase|indirect taxes increase/subsidies decrease| |Future expectations of price|prices are expected to fall|prices are expected to rise| |Technology|technology increases|technology decreases| |Number of firms|firms join market|firms leave market|

Psychology

What is a synapse in psychology?

The synapse is the junction between two neurons and includes all the components necessary for neural communication within the nervous system. It consists of the terminal sacs (or vesicles) located at the axon terminal of the presynaptic neuron, the synaptic gap (or cleft) between the neurons, and the receptor sites on the dendrites of the postsynaptic neuron. When a neurotransmitter (a chemical messenger) is released from the terminal sacs of the presynaptic neuron, it crosses the synaptic gap and binds with complementary receptors on the postsynaptic neuron. These neurotransmitters can either stimulate or inhibit the activity of the postsynaptic neuron. In doing so, neurotransmission can influence human behaviour. Whether a neurotransmitter has an excitatory or inhibitory effect depends on the type of neurotransmitter and the specific receptors involved in the synapse.

Explore More IB Math Resources

Over 80% of IB students globally are experiencing the power of Revision Village

Questionbank

Practice Exams

Key Concepts

Past Papers

Explore More IB Math Resources

Over 80% of IB students globally are experiencing the power of Revision Village

Questionbank

Practice Exams

Key Concepts

Past Papers