Biology Flashcards Second Edition

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  • Created by: AKR28
  • Created on: 02-03-14 15:24
What is a chromosome?
A chromosome is a thread of DNA made up of genes.
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What is a gene?
A gene is a length of DNA that codes for a protein.
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What is mitosis?
Mitosis is a type of division of the nucleus that gives rise to genetically identical cells in which the chromosome number is maintained by the exact duplication of chromosomes.
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What is meiosis?
Meiosis is a type of division of the nucleus to reduce the chromosome number by half. Diploid nuclei give rise to haploid nuclei. Also called a reduction division.
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What is an allele?
An allele is any of two or more alternative forms of a gene.
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What is the genotype of an organism?
The genotype of an organism is the alleles it has.
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What does homozygous mean?
Homozygous is a genotype where both alleles of a gene are identical.
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What does heterozygous mean?
Heterozygous is a genotype where the two alleles of a gene are different.
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What is the phenotype of an organism?
The phenotype is the way the alleles are expressed in an individual.
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What is monohybrid inheritance?
Monohybrid inheritance concerns the inheritance of a single characteristic, such as plant height or flower colour.
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What is codominance?
Codominance occurs when both alleles are expressed in the phenotype, as neither is dominant over the other.
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What is continuous variation?
Continuous variation is influenced by genes and the environment resulting in a range of phenotypes.
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What is discontinuous variation?
Discontinuous variation is caused by genes alone and results in a limited number of distinct phenotypes.
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What is a mutation?
A mutation is a change in a gene or to the number of chromosomes.
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What is the cause of Down's syndrome?
Down's syndrome is caused by an extra chromosome 21.
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What factors increase the mutation rate?
Ionising radiation and some chemicals increase the mutation rate.
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What are the advantages of industrial production of insulin when compared to agricultural production?
Diseases are not transferred from animal to human. Insulin is made more quickly. Animals are not harmed/killed and can be used for other purposes. Industrial production is cheaper than killing pigs and cattle.
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What do nitrogen-fixing bacteria do?
Nitrogen-fixing bacteria are found in root nodules of legumes. They fix nitrogen (N2) by converting it to ammonia.
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What do decomposers do?
Decomposers break down dead remains and animal waster releasing ammonium ions into the soil. This process is called ammonification.
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What do nitrifying bacteria do?
Nitrifying bacteria convert ammonia to nitrate ions.
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What do denitrifying bacteria do?
Denitrifying bacteria convert nitrate ions to nitrogen gas (N2).
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What is the lag phase?
The lag phase is when doubling of the numbers has little effect as the numbers are so small. Bacteria take up water and nutrients, to make new cytoplasm, DNA and enzymes.
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What is the exponential/log phase?
The exponential/log phase is when the population is increasing rapidly. The population increases by doubling and there are no limiting factors, such as food or water.
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What is the stationary phase?
The stationary phase is when bacterial cells are dying at the same rate at which they are being produced. This may be because of shortage of food or because waste products are building up.
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What is the death phase?
The death phase, when more cells are dying than are being produced, so the population declines. Causes of death may be lack of food, shortage of oxygen or a build-up of toxic waste products.
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What are carbon sinks?
Carbon sinks are areas that store carbon in long-lived plant materials, and where there is little decomposition so dead vegetation forms peat that 'locks up' carbon for a long time.
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What is flue gas desulfurisation?
Flue gas desulfurisation removes the sulfur from power station chimneys by treating the waste gases with wet powdered limestone, neutralising the acidic gases before they can escape.
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What are five kingdoms of living things?
The kingdoms are animals, plants, fungi, protoctists and prokaryotes (bacteria).
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What are the seven characteristics of living organisms?
The seven characteristics are: nutrition, respiration, movement, growth, excretion, sensitivity and reproduction.
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What are nematodes?
Nematodes or roundworms are a group of worms that have thread-like bodies that taper at mouth and anus. They have no obvious head and no legs. Their bodies are not made up of segments.
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What are annelids?
Annelids are worms with soft bodies made up of segments. Some have paddle-like extensions for moving and they have chaetae or bristles for making contact with mud or soil.
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What are molluscs?
Molluscs have soft bodies that are not segmented. They have a muscular "foot" that they use for burrowing or movement. Many species of molluscs have one or two shells for protection.
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What are crustaceans?
Crustaceans have a body divided into a cephalothorax (head-thorax) and abdomen. Crustaceans have two pairs of antennae and compound eyes. They have between 5 and 20 pairs of legs. They breathe using gills. Nearly all of them live in water.
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What are myriapods?
These are the centipedes and millipedes. They have long bodies made up of many segments. Centipedes have one pair of legs on each segment. Millipedes have two pairs of legs on each body segment.
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What are insects?
Insects have bodies that are divided into three parts: head, thorax and abdomen. On the thorax there are three pairs of legs and many species have two pairs of wings. They have one pair of antennae on the head and compound eyes.
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What are arachnids?
Their bodies are divided into two parts, the cephalothorax and abdomen. Arachnids have four pairs of legs and no wings. They have several pairs of simple eyes.
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Describe the structure of bacteria.
Bacteria have a simple cell structure. There is no nucleus, just a loop of DNA within the cytoplasm. Bacteria often have additional loops of DNA inside their cytoplasm called plasmids. They do not have chloroplasts or mitochondria.
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Describe the structure of fungi.
Fungi are mostly multicellular. Each cell has a nucleus and cell wall which is made out of chitin. The main fungus body is called the mycelium. It consists of a branching network of threads or hyphae which grow over the surface of its food source.
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Describe the structure of viruses.
Viruses are extremely small. They are particles made up of genetic material surrounded by a protein coat.
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What are dicotyledons?
Dicotyledons have two cotyledons (seed leaves) in a seed. Their leaves are often broad with a network of branching veins.
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What are monocotyledons?
Monocotyledons have one cotyledon (seed leaf) in a seed. The leaves of most monocotyledons have parallel veins such as grasses.
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Other cards in this set

Card 2


What is a gene?


A gene is a length of DNA that codes for a protein.

Card 3


What is mitosis?


Preview of the front of card 3

Card 4


What is meiosis?


Preview of the front of card 4

Card 5


What is an allele?


Preview of the front of card 5
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