E.6d Food, Sleep, Sex

Foraging is defined as the searching for food, and through studies, it has been found that animals tend to choose a prey that gives the highest rate of energy return. Foraging behaviors can change for many animals because availability of food changed depending on the space and time. For instance, if there are low availability of prey, animals tend to eat all sizes of that prey. However, if the prey is readily available, animals tend to eat larger sizes of their prey.

Many animal species show rhythmical behavior, which can be in an annual cycle. For instance, mate selection in certain animals only occurs during certain seasons. For some animals such as the red deer, this is so that the babies are born in the spring when food is readily available. There can also be daily cycles such as diurnal sleep and nocturnal activity in hamsters.

Some species have exaggerated traits, which can be in the form of behavior or anatomical features. An example is the tail feathers of the peacock, that is very showy to attract mate. Such traits indicates fitness and the possession of good genes.

E.6b Reciprocal Altruism

If Natural selection was absolute, it would always favor against altruism. But, it turns out that helping others at the expense of the well-being of yourself can pay-off when you’re the one that needs help from time to time. As natural selection selected for the alleles which contributed to altruism, the organisms which did not exhibit these types of behaviors did not pass on their genes, thus erasing the characteristic. Honey bees and vampire bats are examples of altruistic organisms.

E.6c Kin Selection

Natural selection works on the population, rather than individuals to allow the maximum number of survival.

Honeybees are an example of a social organism that lives together to maximize survival. They are divided into three groups: queen, drone, rearing larvae. The queen is responsible of reproducing and the others are responsible for other jobs including finding food and protecting the shelter. This behavior can be described as being altruistic since infertile female and male are working for the queen without a clear benefit.

Although altruism contradicts survival at the individual level, it may help survival of the whole population, and thus is sometimes valued evolutionarily.

E.3b Learned Behavior

1. Sonogram 1 and 2 both include a rapidly fluctuating frequency which rises and drops in a short matter of time. Sonogram 1 consists of six different types of sound, whereas sonogram 2 consists of only 3. The average frequency at which the song is played is similar for both songs 1 and 2.

2a. Song 3 shown on sonogram 3 plays at a higher frequency on average than sonogram 1 and 2 representing songs 1 and 2. Compared to sonogram 1 and 2, the lines of sonogram 3 are thicker, indicating that the volume of the sound was also higher on average on sonogram 3.

2b. The song of the white-crowned sparrow is both innate and learned. Sonogram 3, which shows the song of a bird which was reared and was not exposed to the same environmental factors as birds 1 and 2, still had a very similar song pattern as bird 2 indicating that the song was to a large extent innate. However, sonogram 1 which is from a different population from the other two birds, show slight variations in the song pattern indicating that external factors have influenced its song. This means that it had learned the pattern that it currently sings.

3a. Both sonograms IV and V start from a high frequency and end in a lower frequency. Sonogram V shows a long continuous note played at the beginning whereas sonogram V shows a succession of short sounds.

3b. Both sonograms V, I, and II start off with a long note at the beginning. However, whereas this long note shows at least 1 rapid decrease and increase in frequency for sonograms I and II, the long note in the beginning does not show any rapid changes in frequency for sonogram V. Sonogram V also starts at a high frequency and ends at a low frequency, whereas sonogram I and II does not.

3c. One reason is because bids identify potential mates of their own species with the songs. If a species imitated the song from another species, it would have trouble attracting mates from the same species and passing on their genes. Another reason may be because the birds may attract certain predators which may be attracted to certain bird songs. All species are adapted to have some defense against their natural predators, but by imitating a song from another species, they may attract predators that they are less able to defend themselves against.

3d. This is evidence for mostly learned development of birdsong, as a bird was able to overwrite the genetic code for singing the song of their species, and learn the song of another bird which was in the same aviary. However, the learned song from the white-crowned sparrow still showed similarities with the normal songs of its own species, indicating that the innate tendency to sing the song of its own species did not completely disappear.

E.3a Innate Behavior

DBQ

1)Another method that can be used is visual stimuli. Actual woodlice of the same species can be placed in either of the arm, and an observation can be made. It is more likely that the woodlice will travel to the arm containing its own species than the arm containing nothing.

2) The data suggests that the woodlice are attracted to the scented arm more than the unscented arm. In species, more were collected int he scented arm.

3) The woodlice must have scent receptors that respond to smell, as they are attracted to a certain smell. Furthermore, the scent of same species might cause a pleasure response in terms of dopamine.

4a) In terms of survival and reproduction, the woodlice might enter the scented arm because it is a indicator that there are possible mates in that arm. Scent is possibly a sexual features that attracts woodlice to each other.

4b) Some woodlice might travel to the unscented arm to avoid competition. There might be competition for mate, and some may choose to survive over to reproduce.

E.1 Reflexes

Neurobiology is the study of the nervous system, which is involved in responses to stimuli. An response involves a series of neurons that are called a reflex arc. The example below illustrates the response to pain.

1. Pain receptors (nerve endings of sensory neurons) detect pain.
2. The impulse is carried from the pain receptor to the central nervous system.
3. The impulse travels to the ends of the sensory neuron where message are passed to the relay neuron.
4. The relay neurons then passes the impulse to motor neurons, which carry the impulse out of the CNS. The impulse travels to the muscle.
5. The impulse is finally carried to the muscle fiber, which caused the muscle to contract, creating the physical reaction to pain.

E.4c Neurotransmitters & Drugs

Cocaine

Cocaine acts as synapses that use dopamine as a neurotransmitter. It binds to dopamine reuptake transporters, which causes dopamine to build up in the synaptic cleft. As a result, the post-synaptic neuron is continuously excited.

Tetrahydrocannabinol (THC)

THC on the other hand, binds to cannabinoid receptors in the pre-synaptic membrane. This inhibits the release of neurotransmitters, which causes excitation of post-synaptic neurons.

Drug Addiction – The Causes

Addiction is defines as “a chronically relapsing disorder that is characterized by three main elements: compulsion to seek and take the drug, loss of control in limiting intake and emergence of negative emotional state when access to the drug is prevented.

There are three areas that needs to be considered in drug addiction.

Dopamine

• Many drugs affect dopamine secretion, since dopamine is associated with the feeling of pleasure.

Genetic Predisposition

• Some people are more likely to become addicted to drugs than others. This is a result of their genes, and one example is the gene DRD2.

Social Factors

• Peer pressure, poverty, social deprivation, traumatic life experiences and mental health problems may all contribute to the usage and addiction to drug.

E.4b Neurotransmitters & Personality

Neurotransmitters and Synapses

More than one pre-synaptic neuron can form a synapse with the same post-synaptic neuron, meaning that an impulse can be carried from several neurons to one neuron. Usually, neurotransmitter must be repeatedly released, or several neurons must release neurotransmitters to trigger an action potential. This additive effect of neurotransmitter is called summation. Also, some neurotransmitters act as inhibitors.

Psychoactive Drugs

Psychoactive drugs affect the brain by altering the function of such synapses. Some are excitatory, which increase post-synaptic transmission, whereas others are inhibitory, which decrease post-synaptic transmission.

Excitatory Drugs

• Nicotine
• Cocaine
• Amphetamines

Inhibitory Drugs

• Benzodiazepines
• Alcohol
• Tetrahydrocannabinol (THC)

E.4a Neurotransmitter & Synapses

Medulla Oblongata: Controls automatic and homeostatic activities (swallowing, digestion, vomiting, breathing, and heart activity)

Cerebellum: Coordinates unconscious functions, such as movement and balance.

Hypothalamus: maintains homeostasis, coordinating the nervous and endocrine system. It synthesizes the hormones secreted by the posterior pituitary, and releases factors that regulate the secretion of hormones by the anterior pituitary.

Pituitary Gland: Posterior lobe–sores and releases hormones produced by the hypothalamus.
Anterior lobe–produces and secretes hormones that regulate many body functions.

Cerebral hemisphere: Acts as the integrating centre for high complexity functions such as learning, memories, and emotions.

Lesions which cause dysfunction in the brain can be studied to see what part of the brain is responsible for what functions. Animals are often used as subjects, raising ethical issues about animal rights.

fMRI allows us to see which part of the brain is used/stimulated when subject to a stimuli. This allows us to understand the functions of the brain better, and advances in this field may be able to replace vivisections used on animals.

E.5b Brain Function

The peripheral nervous system comprises all of the nerves outside the central nervous system. Is consists of the sympathetic and parasympathetic systems which are often opposites of each other. When bright light is shown in the eye, the parasympathetic system causes the pupils to constrict. When there is less light, the sympathetic system causes the pupil to dilate to enable more light to pass through the pupil. These functions are controlled by the medulla oblongata. If light is shown in the eye and no change occurs, we can assume that the medulla oblongata is damaged, and in worse case scenarios, the patient is brain-dead. However, because being brain-dead does not necessarily mean that the patient is not living, it raises ethical issues and debates as to what would be considered a “dead” being.