Unit 3B Flashcards
Nitrogen
Used to make amino acids which are used to build protein.
All new cells are built of protein, so protein is essential for growth.
Nitrate
The form in which nitrogen enters the plant, dissolved in soil water.
Soil water enters the root through root hair cells.
This is known as uptake or assimilation.
Legumes
Plants such as peas, beans and clover.
They have bacteria living in their roots which are able to absorb nitrogen directly from the air into the roots.
Animal proteins
Animals can only obtain protein by eating other organisms.
Herbivores eat plant protein, carnivores eat animal protein.
Protein moves along a food chain from one consumer to the next.
Nitrogen cycle
A series of chemical reactions that allow nitrogen to be recycled through ecosystems.
Many of the steps are carried out by bacteria.
Decomposers
Bacteria and fungi which break down dead material by feeding on it.
They release ammonia (which contains nitrogen) as a waste product.
Nitrifying bacteria
Live in the soil.
Convert ammonia into nitrites and then into nitrates, which can be absorbed by plants.
Denitrifying bacteria
Live in waterlogged soil.
Convert nitrates back into atmospheric nitrogen.
Nitrogen fixing bacteria
Live in the soil or in the roots of legumes.
They convert atmospheric nitrogen into ammonia or nitrates.
Essential plant minerals
Nitrogen (N), phosphorous (P) and potassium (K).
Fertilisers
Used to replace nutrients lost in harvesting.
Used to improve crop yields, as crops grow better with fertiliser.
Natural (organic) fertilisers
Waste materials produced by living organisms. eg. manure, straw, bird droppings (guano)
Advantages - good use of natural waste materials, improve and bind the soil
Disadvantages - release nutrients slowly, are bulky and hard to spread.
Artificial (inorganic) fertilisers
Chemical fertilisers made in factories.
Different fertilisers have different combinations of minerals for specific uses - known as N:P:K ratios.
Advantages - easy to apply, nutrients released quickly and in specific quantities
Disadvantage - wash into rivers, expensive
Overuse of fertilisers
Excess fertilisers can be washed off the land into rivers, lakes and the sea.
This results in algal blooms, which block the light for other plants and kill them.
As dead plants and algae are decomposed by bacteria, they use up the dissolved oxygen in the water.
This kills fish.
Blue Flag Award
Introduced to combat beach pollution and habitat degradation.
Problems caused by beach pollution
Illness due to bacteria in sewage
Loss of recreational areas due to litter and dirty water.
Reduction in biodiversity if wildlife are killed.
Loss of coastal habitats for young fish due to algal blooms.
Evolution
Species change over time to become better adapted to their environment.
Adaptation
Any feature that makes an individual better suited to their environment, and able to survive long enough to reproduce.
Well adapted species survive.
Less well adapted species become extinct.
Adaptations can be structural, physiological or behavioural.
Structural adaptations
Describe how the body of an organism is suited to its environment.
This affects what it looks like.
eg. polar bears have thick fur and a fat layer for warmth, their fur is white for camouflage, they have small ears to reduce heat loss.
eg. cacti have leaves reduced to spines to deter grazers and reduce water loss, they have succulent stems to store water.
Physiological adaptations
An adaptation to the internal processes of a plant or animal.
eg. clover produces hydrogen cyanide in its leaves to stop herbivores eating them.
eg. emperor penguins can store large quantities of oxygen in their blood, allowing them to dive for 22 minutes to hunt.
Behavioural adaptations
Affect the way that an animal behaves, increasing its chance of survival.
Can be innate (inherited) or learned.
eg. grass snakes ‘play dead’, bees do a waggle dance to communicate.
Desert mammals
Live in harsh conditions and use all 3 strategies to survive.
eg. kangaroo rats are camouflaged against the sand, never drink and hide in underground burrows to avoid the sun.
Innate behaviour
Inherited behaviour which is genetically determined.
eg. newly hatched turtles head towards the sea, bees carry out a waggle dance and swarming behaviour.
Can be studied in woodlice using a choice chamber.
Learned behaviour
Not carried out by all members of a species - only those with experience.
Helps organisms to survive.
Stimulus
Triggers a response in an organism.
Can be internal (hunger, thirst) or external (temperature, day length).
Habituation
An animal learns to stop responding to a repeated harmless stimulus.
eg. snails withdraw into their shells to avoid predators, but stop doing it with repeated tapping.
This saves energy and allows them to continue feeding.
Imprinting
Newly hatched ducks and geese follow their mother towards water and food, and away from predators, which helps them to survive.
It is learned behaviour - they learn to follow the 1st large moving object they see (even human foster parents)
Associative learning
Bees can be trained to associate colour with food, which helps them to survive.
If sugar solution is only placed on blue circles in an experiment, the bee will learn to associate the colour blue with food.
Migration
Animals migrate long distances to find food and avoid harsh conditions. eg. whales, swallows
It is both innate and learned.
Birds instinctively fly in the correct direction, but learn the route as they get older.
Group social behaviour
Many animals live in social groups to help them to survive.
eg. orcas, monkeys and many species of bird.
They hunt for food together, watch for predators and stay together for protection - safety in numbers.