Unit 4 - Lesson 2: Evolution and Adaptations (Temperature Control) Flashcards
What does evolution state?
That species develop from earlier forms over many generations.
What is evolution the result of?
The process of natural selection.
What do the genes of an organism (genotype) govern?
Its shape, size, personality, and health (phenotype).
What is natural selection?
The process of only the best alleles (of surviving in that environment) of a gene passing on is called natural selection or ‘survival of the fittest’. This is not physical fitness but biological fitness.
Define Evolution.
Change in form of an organism over time. Process by which species develop from earlier forms during the history of Earth.
Define Natural Selection.
Process by which certain individuals in a population survive because they’re better adapted to their environment. They’re more likely to pass on their genes to their offspring. The mechanism of evolution.
Define Biological Fitness.
How well adapted an individual is to its environment so that it’s successful at reproducing.
Define Adaptation.
Feature of an organism that suits its structure to its function.
Most exam questions about evolution and natural selection can be answered in roughly the same way. What 6 points can help you achieve maximum marks?
- There is variation in the population (of species stated in the question).
- A DNA mutation results in an individual having an allele that is favourable to the environment.
- Those with the allele survive (the fittest survive/survival of the fittest).
- They reproduce.
- Passing on the favourable allele to the offspring.
- After many generations, the whole population has that allele.
EXAMPLE EXAM QUESTION: A large ground finch has a large beak and feeds on big seeds with hard seed coats. The cactus finch feeds on nectar from cactus flowers.
Explain how the beak of the cactus finch could have evolved by natural selection.
There is variation in the beak of the large ground finch.
A DNA mutation causes the beak of the individual to lengthen.
That individual survives.
That individual reproduces.
That individual passes on the allele for a long beak to offspring.
After many generations, there’s a whole population of finches with a long beak.
What is a selective advantage?
Individuals who have an adaptation that favours the environment have a selective advantage. EG, hoverflies evolved to have stripes (to mimic wasps) for protection from predators. Hoverflies with stripes had a selective advantage over those without.
What is selective pressure?
Environments can change. This is called selective pressure. Organisms must evolve by natural selection to adapt successfully to these changes.
Give some examples of adaptation.
Streamlining, insulation, camouflage, mimicry, thorns, and spikes.
What adaptations do polar bears have for survival?
- Paws with a high surface area (wide and large): Good for swimming and walking in snow.
- Nostrils close when swimming: Can swim under water.
- Good sense of smell: Detect prey.
- Layer of thick fat: Insulation to stay warm.
- Strong legs: Can swim for days.
- Thick, white fur: Camouflage and reduce heat loss.
- Small surface area to volume ratio: Reduce heat loss.
- Short, strong claws: Provide grip to hold heavy prey.
Why can it take a very long time for us to see the effects of natural selection?
Most organisms reproduce slowly.
What organisms reproduce fast and therefore allow us to observe natural selection?
Bacteria. They’re adapting to antibiotic use and are evolving to become resistant.
Insects. They’re becoming resistant to pesticides.
START OF REVISION SHEET 2 - FILLER CARD
START OF REVISION SHEET 2 - FILLER CARD
What is homeostasis?
Homeostasis is the process of maintaining constant internal conditions in the body, normally via the blood and tissue blood.
What is tissue fluid?
Tissue fluid is water, salts, glucose, and other useful molecules leaked from capillaries that surrounds all cells. It’s like plasma without the plasma proteins.
Why is homeostasis important?
Homeostasis is important because cells must be surrounded by blood or tissue fluid with the correct levels of these molecules. For example, too many salts and cells could shrivel by osmosis. Too high a pH or temperature and enzymes slow or denature, affecting processes like respiration.
Give some examples of homeostasis.
Maintaining blood glucose concentration, pH, carbon dioxide levels, and the temperature of the body.
Homeostasis maintains body temperature.
a) During which process do all living organisms give off heat?
b) What is metabolism?
c) What does the amount of heat given off depend on?
a) All living organisms give off heat when they metabolise.
b) Metabolism is the sum of all the chemical reactions (e.g. respiration) occurring in your body.
c) Many factors. Organisms have methods to maintain these losses and in turn survive variations in the temperature of their environment.
What are heterotherms? Give an example. What do they rely on for body temperature?
Heterotherms are cold blooded. They have no way of controlling their body temperature internally, so rely on their environment to keep them warm. An example includes snakes. They bask in the sun to warm up and move to the shade when they must cool?
What are homeotherms? How many degrees do homeotherms control their body temperature to? How does this help their metabolism?
Homeotherms are warm blooded. They control their body temperature to a stable 37 degrees Celsius (normally). This helps keep their metabolism working efficiently as enzymes controlling the reactions like this temperature.
