B2a Flashcards
What can organisms be classified into groups according to?
Shared characteristics.
What are the characteristics used to place organisms into the five kingdoms?
Animals - Cells do not have a cell wall. Multicellular and feed on other organisms.
Plants - Cells have a cellulose cell wall. They use light energy to produce food by photosynthesis.
Fungi -Cells have chitin cell walls. Reproduce using spores rather than seeds.
Bacteria - Have a cell wall but not made from cellulose. Cells have no nucleus.
Protozoa - Exist as single cells.
What is the difficulty of variety of life being a continuous spectrum?
It is difficult to place organisms into distinct groups.
What are the different groups for classification?
Kingdom Phylum Class Order Family Genus Species
What is the importance of classification systems?
They help us to understand how organisms are related (evolutionary relationships) and how they interact with each other (ecological relationships).
What are the two classification systems?
Natural classification systems are based on the evolutionary relationships and genetic similarities between organisms.
Artificial classification systems are based on appearance rather than genes. They’re used to identify organisms.
How has the use of DNA sequencing information led to changes in understanding of classification?
It allows us to see genetic differences between different groups. As this data is collected, we might find out that two groups aren’t actually as closely related as we’d thought - or two groups that we thought were very different might turn out to be close relatives.
Why do classification systems change over time?
When a classification system is created it fits everything we know so far about different groups of organisms . But as scientists discover new species, they might have to adapt classification systems to fit their new findings.
What are the different classes of arthropods?
Insects, arachnids, crustaceans and myriapods.
What can be used to display the evolutionary relationships between organisms?
Evolutionary trees.
How can the evolutionary relationships between organisms be understood and how has this been facilitated by ICT?
By analysing lots of different genes responsible for lots of different characteristics. Studying lots of characteristics for a large group of organisms involves analysing huge amounts of DNA data and is only really possible thanks to advances in ICT.
What may organisms in the same species show and have?
They may show great variation and have more features in common than they do with organisms of a different species.
What does the term ‘species’ mean?
A species is a group of organisms which can interbreed to produce fertile offspring.
What is the importance of the binomial system as the international basis for naming species?
It is used by scientists all over the world as the international basis for naming species. It means that scientists in different countries or who speak different languages all refer to a particular species by the same name - avoiding potential confusion.
What are some of the problems of classifying organisms into species?
Hybrids - if you interbreed a male from one species with a female from a different species you’ll get a hybrid. But hybrids are usually infertile so they aren’t new species, which makes it difficult to classify them.
Asexual Reproduction - where an organism reproduces by making a copy of itself. There is no interbreeding with another organism so they don’t fit the definition of a species.
Evolution is a continuous process - organisms change and evolve overtime, so the way they’ve been classified might also have to change. Sometimes a group of organisms will change so much it will form a new species, but it can be difficult to tell when this has happened.
