Explanation​:
SSRIs (selective serotonin reuptake inhibitors) are drugs that act as agonists/antagonists. SSRIs selectively inhibit or block the reuptake of the neurotransmitter serotonin from the synaptic gap, increasing serotonin concentration in the synapse. SSRIs allow serotonin to build up between neurons so messages are sent correctly.

Explanation​:
The nervous system comprises neurons consisting of soma, dendrites, and axons. A synapse or synaptic gap is the space between two neurons. An action potential is a process in which one neuron sends a message to the other neurons through an axon. An action potential is an all-or-none phenomenon. When it reaches the end of the axon, a neurotransmitter is released in the synaptic gap from the axon terminals.

Explanation​:

The biological approach in understanding human behaviour emphasises the role of genetics and other physiological factors in influencing personality and behaviour. Answers A, B, and C do not have this emphasis.

Explanation​:
Twin studies aim to explore the interplay between genetics and the environment in shaping traits or behaviours. Researchers can discern the impact of genetics and environment on individual differences by comparing similarities between identical (monozygotic) and fraternal (dizygotic) twins. Kinship studies extend this investigation to non-twin relatives, investigating how traits vary across degrees of relatedness. These studies provide valuable insights into the complex interactions between genes and the environment in shaping human development and behaviour.

Explanation​:

An action potential, also called a nerve impulse, is an electrical charge that travels along the membrane of a neuron. It can be generated when chemical signals change a neuron’s membrane potential from a nearby cell. A, neurotransmission is the transfer of information between neurons. B, synaptic reuptake refers to the reabsorption of neurotransmitter molecules by the presynaptic neuron that released them and C, a receptor site, is the space on the cell that houses the receptor.

Explanation​:
The 5-HTT or serotonin receptors are found in the central or peripheral nervous system. 5-HTT stands for 5-hydroxytryptamine. Serotonin receptors affect many processes, such as memory, sleep, appetite, aggression, and anxiety. A study done by Caspi et al. in the year 2003 shows depression was also linked to a particular gene—the serotonin transporter gene 5-HTT.

Explanation​:
Vasopressin has been found to play a role in stable, long-term pair bonding in prairie voles. Prairie voles are rodents who actively select mates, are monogamous, share parenting and are characterised by long-term pair bonds.

These social characteristics found in them, along with similar brain structures and neurochemical make-up, make them a perfect sample to study social behaviour in humans.

Explanation​:

The evolutionary approach, using Charles Darwin’s concepts of evolution and adaptation, suggests that our ability to adapt to new situations and environments directly results from evolution.

Answer A is incorrect because humanistic psychology emphasises achieving a person’s holistic growth in terms of love, fulfilment, and self-worth.

Answer B is incorrect because the Freudian concept of psychoanalytic psychology emphasises the influence of the unconscious and childhood experiences on behaviour and personality.

Answer D is incorrect because the biopsychosocial perspective suggests that physical and mental health is affected by biology, psychology, and social stressors.

Additionally, the amygdala, together with the hippocampus, are both involved in emotion and cognition as they are central to processing emotion in relation to cognitive processes such as memory.

Explanation​:
Pheromones are chemical messengers used for communication among the same species. There is evidence for the existence of pheromones, and there is evidence that shows that pheromones don’t affect behaviour.

A few common critical evaluation points found in the research done for pheromones are - population validity, construct validity, ethics, demand characteristics as most research is for a self-selected sample, lack of internal validity due to the effect of extraneous variables, replicability because the nature of human behaviour is constantly changing.

Explanation​:

Answer C is correct because the study mainly focused on the heritability of intelligence and the influence of upbringing.

Answers A, B, and D are incorrect because the study did not specifically focus on birth order, cultural factors, or physical health outcomes.

Explanation​:
The phenomenon where genetic predisposition causes individuals to select environments that affect their behaviours is called niche picking. Individuals seek our particular/specific environments based on their experiences. For example - a student showing symptoms of borderline depression will choose complicated options where they are not likely to succeed, such as demanding environments causing stress.

Explanation​:
A, B and C are functions of the MRI, whereas D is the function of the positron emission tomography (PET) scans.

MRI scans use magnetic fields and radio waves to produce 3D computer-generated images. All metal objects and clothing on the body have to be removed before lying in the MRI machine. This is a disadvantage of the technique, as people with metallic implants cannot use this technique.

Explanation​:

Answer C is correct. The study of genetic adaptations of behaviours and other psychological traits is a focus of evolutionary psychology.

Answers A, B, and D do not focus on genetics, evolution, or adaptation.

Explanation​:
EEG - Electroencephalography measures the electric potentials generated by the neural circuits; neurons here interact with each other by sending electrical impulses. In this method, electrodes are attached to the scalp and pick up the changes in the electric potential of the scalp areas. EEG has a perfect temporal resolution and can detect changes in brain activity within milliseconds. Because of this, it outperforms techniques such as fMRI.

Explanation​:
Phenotype is the set of traits that manifest in an individual's body, appearance, or behaviour. The set of traits as coded in an individual's DNA is called a genotype.

Phenotype comprises observable characteristics (eye colour, height) and unobservable characteristics (blood type, immune system). Genotype is the plan, and phenotype is the implementation of the plan.

The results showed that oxytocin was linked to in-group trust and cooperation, and aggression towards the members of the out-group.

Explanation​:
Regulation of gene expression results in epigenetic changes, which mean deviation of phenotypes from the genetic code in the DNA sequence. Epigenetic changes can be attributed to environmental factors explaining how nurture influences nature in certain situations. Epigenetic changes can affect the growth of neurons in a baby’s developing brain and brain activity in adults. They result in a change of behaviour in individuals.

Explanation​:
Molecular genetics studies use modern technology for genetic mapping and identifying the alleles of particular genes in a particular individual. Genetic variants are then correlated with observed behaviour. These methods are commonly used to identify specific genes responsible for specific behaviour. For example, the gene that causes depression, the gene that causes aggression.

Explanation​:
Behavior results from genetic factors and natural selection. The evolutionary explanation of behaviour explains that certain behaviours have lasted over many generations (i.e. survival tendency) and, as a result, have been encoded in the genes of organisms. They are subject to natural selection.

Explanation​:
Split-brain studies represent research on brain lateralisation which is the division of functions between the two hemispheres of the cortex. Lateralization is a particular case of localization. Roger Sperry conducted initial animal research to understand this phenomenon.

Explanation​:
Serotonin is a neurotransmitter responsible for regulating essential bodily functions, including mood, sleep, and learning and memory processes. It acts as a chemical messenger and passes messages from the brain to the rest of the body. Serotonin deficiency can result in depressive symptoms and anxiety in people.

Explanation​:
Synaptogenesis is an explosion of synaptic formation between neurons during early brain development. The brain experiences a lot of growth during infancy. This period of synaptogenesis plays an essential role in learning, memory formation. Active synapses are strengthened, and less active synapses are weakened. The process of removing the irrelevant/pruned synapses is referred to as synaptic pruning.

Explanation​:
Twin studies are small in sample size and rare due to the uniqueness of their target group. It becomes difficult to collect samples depending on the aim of the research. Twin studies are on monozygotic or dizygotic twins or both. This results in issues with the replication of similar studies.

Options A, B and C are strengths of twin studies.