Biology 1b

Animal and plants survive in many different environments. This is because they become adapted to that environment. 

Desert animals have adapted to save water: Animals that live in hot, dry conditions need to keep cool and use water efficientely. 

• Large surface area compared to volume,
• Efficient with water,
• Good in hot sandy conditions,

Desert animals adapt as they have:

• Large feet - so their feet doesn't sink in the sand,
• A sandy colour- camouflage,
• Lose less water - from concentrated urine,
• Less sweat,

Arctic animals that live in very cold conditions need to keep warm:

• Small surface area compared to volume,
• Well insulated,
• Good in snowy conditions,

Arctic animals ensure they have these by:

• White fur - camouflage in their surroundings,
• Thick hairy coats - to keep them well insulated,
• Big feet - spreads weight so they don't fall into snow or thin ice,
• Thick layer of blubber got insulator and a energy store

Desert dwelling plants make best use of what little water is available:

• Minimising water loss,
• Maximising water absorption,

They do this by:

• Spines instead of leaves - to reduce water loss,
• Small surface area to reduce water loss,
• Stores water in thick stems,

Some animals have armour to avoid their predators - like roses (thorns) catic with (sharp spines) and tortoises (with hard shells)!!

Others produce poisons - like bees and poison ivy,

Warning colours!!

The size of any population depends on three main factors:

1. Competition - plants for light, water and space - animals for space, food, mates and water,

2. Disease - Infectious diseases can kill members of a population - animals that are fit and healthy stand a better chance of survival,

3. Predation - If a animal gets eaten its population will decrease. 

Organisms compete for resources:

1. Live where they can find resources, 

2. Competition - therefore some habitats only support a certain number of species, 

3. Space in which there is resources,

In 1876 the grey squirrel was introduced to the UK, the native red squirrel was unable to compete very well with the larger grey squirrels - causing the red squirrel population to decrease, 

The grey squirrel is better adapted because: 

• The deciduous woods,

However the red squirrel is best adapted in the coniferous forests because they eat conifer seeds,

Different species look different - heights, wight, nose etc.

These differences are called variation:

• Genetic variation,
• Environment variation,

Different genes cause genetic variation:

• Different characteristics similar to their parents, - characteristics are determined by genes inherited from their parents,
• Most animals get some genes from their mother and some from their father - combining of genes causes genetic variation,
• Some characteristics are only controlled by genes like - colour of plants, eye colour, inherited disorders and blood group,

Characteristics are also influenced by the environment,

• The environment that organisms live and grow cause differences,
• For example in a sunny place you can suntan,
• Basically any difference that has been caused by the conditions something lives in is called environmental variations, 

Plants grown in darkness - tall, spindly and the leaves are yellow,

Plants grown in the sun - luscious and green,

Most characteristics are due to genes and the environment,

• Most characteristics like body weight, eye colour, skin colour, height etc are determined by a mixture of genetic and environmental factors,
• The maximum height a plant can grow to is determined by its genes,