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Populations

• Animals and plants have adaptations to help them survive.
• Living things compete for resources that are in short supply, such as food.
• Many animals, such as robins, compete for territory.
• Weeds such as dandelions are successful competitors because they are well adapted.
• Some animals and plants compete with humans and are called pests.
• Predators are adapted to kill animals for food.
• Prey species are adapted to escape from predators.
• A population is a group of animals or plants living in the same habitat.
• populations are able to grow very quickly in good conditions.
• Some factors limit population growth, such as climate, disease and overcrowding.
• Human populations can grow very quickly.

In this section we will learn all about nature and how animals and plants compete and survive. We start off by discovering how to read and write keys in order to identify animals and plants and be able to sort them into groups.

When making a key we must try and think of questions that would allow us to separate them into groups to make them easier to identify. Some of the questions we can ask are:-

"Is it alive?"; "Has it got less than 4 pairs of legs?"; "Is it red?"; or whatever question that will split the group up.

All plants and animals compete (fight against each other) for resources like food, space to live, a mate, water or light. The plants that compete the best are the most successful. Even individuals within a population (ie zebra in a herd) compete against each other!

We also look at relationships between different species and predator prey relationships. These can be shown in a graph of the number of individuals of the species and tell a story about how their numbers vary and how their numbers depend on each other. When there are a lot of predators, they need to eat and so the prey numbers are reduced. This means that there is not enough food for the predators and so some of them die and their numbers decline. Because there are less predators eating the prey then their numbers rocket and so the cycle starts again!

We looked at what animals we would find living in our school grounds and in the leaf litter around the base of the trees around the playing fields. We expected to find a lot of ants but also found worms, centipedes, spiders, mites and range of other beasts.

Hunting in the school grounds!

What you should be able to do.

• Use a key to identify living things.
• make a key to identify living things.
• List the adaptations that a plant or animal shows to help it survive.
• Plan an investigation to find out what conditions woodlice like.
• Investigate how successful weeds are in the school gardens.
• Play a game which shows predator-prey relationships.
• Understand the relationship between the numbers of predators and the numbers of prey.
• Suggest how different factors can limit population size.
• Plan an investigation into the growth of duckweed.
• Suggest the factors that affect the growth of human populations.