Year 11 Biology Term 2 Modules 2 and 3

What are selection pressures?

Factors which affect an organisms ability to survive in a certain environment. They are always acting on the variation present in populations.

Do positive selection pressures increase or decrease chances of survival?

Increase

Do negative selection pressures increase or decrease chances of survival?

Decrease

What are the 2 classifications of selecion pressures?

biotic or abiotic

Are organisms with more ‘favourable’ variations more likely to survive and reproduce or decrease their population and die?

More likely to survive and reproduce.

What are biotic factors?

Living components of the environment. This also includes the way organisms interact with other organisms.

What are some examples of biotic factors?

Birth and death rates, proportion of predators to prey, presence of pathogens, abundance of species, biodiversity.

How can biotic factors act as selection pressures?

All organisms must compete with others to gain the resources they need. Those that compete more successfully will have greater reproductive success. They create selection pressures that can result in evolution of species.

What is an example of species evolving together due to biotic factors?

A predator that exerts selection pressures on its prey and vice versa so predators and prey coevolve: the prey becoming better adapted to escape.

True or false: Biotic factos such as other interactions also affect the direction of evolution in a species.

True - they do affect the direction of evolution.

What is an example of biotic interactions affecting the direction of evolution?

Symbioses such as plants attracting pollinators, changes in one of the symbionts (e.g. redder flower) may ultimately affect the reproductive success of another symbiont and so influence its evolutionary path.

What are abiotic factors

Physical, non-living components of the environment.

What are some examples of abiotic factors?

temperature, abundance of light, wind, soil and availability of water.

How can abiotic factors act as selection pressures?

They play a part in the direction and rate of which species evolve. Rapid changes in the environement can increase the rate of evolution by creating new selection pressures.

What is another name for biotic interactions?

Trophic interactions

What happened to the peppered moths during the industrial revolution?

Their dark (melanic) form survived more than the light form due to the trees becoming dark with soot.

How does what happened to peppered moths show the effect of selection pressures?

The shift in appearance is an example of how favourable phenotypes (in this case, the dark melanic form) become more prominent as they assist more in the survival and reproduction of the animal.

Why did the peppered moths change colour to match the colour of the trees during the industrial revolution?

It was a result of selective predation by birds, as the grey form was more visible than the dark form, making the birds prey upon the light variation more.

In the peppered moth, what allele does the dark form appear as?

M

If the dark form of a peppered moth is on allele M, is it dominant or recessive?

Dominant

After sulfur dioxide and smoke levels dropped after the industrial revolution, what happened to the population of the dark melanic form of the peppered moth?

It decreased

Can diseases act as a selection pressure?

Yes.

Why do some people die from diseases and others survive?

Humans show genetic variation in our ability to resist and combat diseases. Individuals with favourable variations survive over those that do not, meaning that these favourable traits can be passed on through reproduction.

What are pathogens?

Disease-causing organisms

How does high density-populations lead to faster and easier spread of diseases?

As the popualtion is more close together, for example, diseases spread by coughing can be spread to many more people in high-density environments.

How did the domestication of animals and livestock increase diseases humans are exposed to?

Some diseases originated in livestock and pets and could transfer to, and infect, humans.

How can selection pressures make diseases more common?

Some genes with negative diseases can also have benefits as the specific gene variant carrying the disease can assist in preventing a higher-risk disease, as it may restrict the contact between the person and that disease.

What is sickle cell disease?

An inherited condition that causes red blood cells to be shaped like ‘sickles’. It can restrict blood flow and oxygen transport around the body.

How does sickle cell disease occur (other than simply inheriting it)?

A mutation to the gene coding for haemoglobin (oxygen carrying protein inside red blood cells) causes it to fold incorrectly, and the red blood cells become sickle-shaped.

True or false: a person can have a mixture of sickle cells and normal red blood cells.

True - they can have both

What is malaria?

A serious disease that is developed by being bitten by anopheles mosquitoes infected with the malaria-causing parasite.

True or false: Sickle cell disease is a negative selection pressure in regions where malaria is prominent.

False - it is a positive selection pressure in regions where malaria is prominent.

Why were prickly pears intially introduced to Australia?

insects that fed on the Prickly pear gave off a red dye, the British wanted to have their own dye supply to make red army coats, so it got introduced to Australia.

How else were prickly pears used other than the dyes of insects that feed on it?

Hedge plants and animal feedings during droughts

What methods did individuals aim to use to control the spread of the prickly pear?

Digging it up, burning them, crushing them with heavy rollers, and poisoning them.

What act did the NSW government enforce that made landowners responsible for the destruction of prickly pears?

The Prickly-Pear Destruction Act

How did they end up (sort of) controlling the prickly pear population?

Through biocontrol

What exact insect did they use as a method of biocontrol for the prickly-pear population?

A cactus moth

When were cane toads initally introduced to Australia?

1930’s - 1935

Approx how many cane toads were introduced to Australia initially?

2400

How many approx. cane toads do we have now in the present?

200 Million+

True or false: cane toads have no predators in Australia

True - they have no predators

Why do cane toads have no predators in Australia?

They produce a toxin that kills any animal that comes into contact with it, and they are aggressive.

How many eggs do cane toads approx. release at once?

30,000

How have red-bellied black snakes adapted to the selection pressure of cane toads?

They have devleloped smaller heads and larger bodies - so the cane toads can not fit into their mouths and therefore they can not be affected by its poison.

Is the red-bellied black snakes adaptation a selective advantage or disadvantage?

Selective advantage

In percentage, how much have the Northern Quolls populations decreased due to cane toad population increase?

75%

What adaptation have quolls developed due to the presence of cane toads as a selection pressure?

They have avoided eating cane toads as a whole - this trait passing onto their offspring as well.

What is spatial sorting?

The evolutionary mechanism where organisms with the highest movement abilities naturally accumulate at the edge of the invasion front.

What two adaptations have cane toads made according to spatial sorting?

Longer legs and an increased ability to travel faster over greater distances.

In the present, approx how many kilometres can cane toads move forward in a year?

50 km

What are the selective disadvantages of cane toads being at the edge of their invasion front?

They have been shown to develop spinal arthritis and have a slightly lower reproduction rate.

What has been determined about spatial sorting and the environments the organism is in?

In any dispersing population, there are traits that will accumulate in different regions of the dispersing population.

True or false: The most energetic, active and long-legged cane toads outstrip their peers - hence they are found at the invasion frontline.

True - they are found at the frontline

True or false: Spatial sorting cant occur if natural selection does not oppose it.

False - spatial sorting can occur if natural selection does not oppose it.

True or false: Heterotrophs are able to obtain glucose and oxygen needed for respiration from their own cells - like plants.

False

What organ system in animals allows for the obtaining of glucose and other nutritents?

The digestive system

What organ system in animals allows for the obtaining of oxygen from the atmosphere?

The respiratory system

How are substances consumed during respiration carried all around the body/what transport medium is used in animals?

Blood/blood cells

What two products go back into the bloodstream and get exhaled during respiration?

Carbon dioxide and water

What is the word equation for respiration?

Glucose + Oxygen = Carbon dioxide + Water + energy

What are some key differences between photosynthesis and respiration?

• Respiration uses sugar to create ATP (energy) while photosynthesis uses sunlight (energy) to create sugar.

• The reactants of photosynthesis are CO2 and Water, while the reactants of respiration are O2 and Glucose

• The products of photosynthesis are O2 and Glucose while the products of respiration are CO2 and Water

What is the respiratory system in mammals?

A group of organs that allow gases to move in and out of the body.

What are the organs within the respiratory system of mammals?

Airways (mouth and nose), windpipe (trachea), lungs, and diaphragm.

How are the lungs connected to the trachea in the repsiratory system of mammals?

By the bronchi ( bronchus plural)

Each bronchus in the respiratory system then branches into many….

bronchiolas

What do the bronchioles end in at the end of their branches into the lungs?

Aleveoli

What are alevoli (in simple terms)?

Tiny air sacs

What are alveoli’s wrapped in?

Capillaries

What is the purpose of alveolis in the respiratory system?

Allows gases to move in and out of the bloodtsream via diffusion.

How does having millions of alevoli in lungs help gas exchange?

It increases surface area and makes diffusion more efficient.

What is the purpose of capillaries (the ones that cover alveoli’s) in the respiratory system?

To bring deoxygenated blood back to the lungs from the other body cells

What gas diffuses from the blood in the capillaries to the alveoli the capillaries are surrounding (in the context of the respiratory system)?

CO2

What gas diffuses from the alveoli into the capillaries surrounding the alveoli (in the context of the respiratory system)?

O2 - making the blood in the capillaries oxygenated.

How does gas exchange in fish work?

As they swim, they gulp water which passes across and out the gills. The layers of the gills (lamellae) are covered in blood vessels. As the water passes over the blood vessels, dissolved oxygen is absorbed by diffusion, and dissolved carbon dioxide in the blood travels out into the water.

What are some structures in the respiratory system/gas exchange occuring in fish?

Lamellae, gill arch, blood vessels, gill filaments.

What are structures involved in the gas exchange occuring within insects?

Spiracles, trachea, muscles, fluid-filled tracheoles

Where do animals obtain their nutrients and glucose required for survival?

From food

What is physical digestion?

Physically breaking food into smaller pieces - for example, chewing food in your mouth.

What is chemical digestion?

Reactions that break down nutrients into simpler substances - for example, using acids and enzymes to break down chemical bonds in the food.

What are organs involved in the digestive system of mammals?

Mouth, pharynx, oesophagus, liver, stomach, gallbladder, pancreas, small intestine, large intestine, rectum, anus.

What is the function of the mouth in the digestive system?

Takes in food and prepares it for body absorption

What is the function of the oesophagus in the digestive system?

Acts as a transit highway and connects throat to stomach

What is the function of the stomach in the digestive system?

Stores swallowed foods, churns it and uses stomach acids and enzymes to chemically break it down.

What is the function of the liver in the digestive system?

Acts as the central processing plant and filter. It produces bile to break down fats, processes and stores nutrients absorbed from intestines and filters toxins and waste.

What is the function of the gall bladder in the digestive system?

Stores, concentrates and releases bile when you eat, allowing the system to break down and absorb fats.

What is the function of the pancreas in the digestive system?

Drives digestion through exocrine and endocrine function. Exocrine - produces and secretes digestive fluid daily. Endocrine - secreting hormones directly into the blood stream to regulate blood glucose levels.

What is the function of the small intestine in the digestive system?

Finishes breaking down semi-solid foods and absorbs nearly all the nutrients, vitamins, minerals and water for body function.

What is the function of the large intestine in the digestive system?

Absorb remaining water and electrolytes from indigestible food matter, convert liquid waste into solid stool, and house beneficial bacteria that produce essential vitamins.

What are 3 different chemicals in the digestive system?

Bile, stomach acid, enzymes.

What is the function of bile in the digestive system?

Produced by the lvier and stored in the gall bladder; helps break down fats.

What is the function of stomach acid in the digestive system?

Hydrochloric acid with a pH of around 2, helps break down food and kill any pathogens. (e.g. bacteria)

What is the function of enzymes in the digestive system?

Range of different types that break down different substances

How is surface area maximised during digestion?

By the increased SA of food, through chewing and physical digestion.

Also by the increased SA of organs to maximise absorption - e.g. small intestines have villi (tiny folds) and microvilli (tiny hair like structures on their cells) to increase absorption of nutrients.

What is the circulatory system in animals?

The bodys primary transportation network for nutrients, gases, and water.

How are water, nutrients and gases transported in the circulatory system?

Dissolved/carried in the blood.

What is the cardiovascular system?

A network responsible for the pumping and circulating of blood throughout the body.

In animals, what is the name of the fluid that transports the gases, nutrients and wastes around the body?

Blood

How is blood transported around the cardiovascular and circulatory system in mammals?

Via blood vessels and pumped by the heart.

What are the 3 different kinds of blood vessels?

Arteries, veins, and capillaries.