| What does cytosine always bond with? | guamine |
| What is a species? | A group of organisms so similar that they can interbreed to produce fertile offspring. |
| What word means able to reproduce? | fertile |
| What word means unable to reproduce? | sterile |
| What do animals of the same species have the same number of? | chromosomes |
| What happens if different species interbreed? | It is possible that a hybrid could be produced |
| Why are hybrids usually sterile? | Due to the number of chromosomes they have |
| What are some examples of hybids? | zorse (zebra and horse), cama (camel and llama), liger (lion and tiger) |
| What is variation? | All the differences which exist between members of the same species |
| What is discrete variation? | A characteristic that can be used to divide up the members of the population into distinct groups |
| What are some examples of discrete variation? | eye colour, blood type, fingerprint type, hair colour |
| What is continuous variation? | A characteristic that varies from one extreme to the other and does not fall into distinct groups |
| What are some examples of continuous variation? | height, mass, heart rate |
| How is continuous variation displayed? | as a histogram |
| What does a bell shaped curve show on a histogram showing continuous variation? | a normal distribution |
| Where is genetic information stored? | On chromosomes in the nucleus |
| What is meant by characteristics? | The appearance of the organism |
| Where does genetic information come from? | Gametes, one set comes from the male and one set comes from the female |
| What does haploid mean? | One set of information |
| What does diploid mean? | Two sets of information |
| What is a zygote? | A cell formed by a fertilisation event between two gametes |
| Where is an egg fertilised? | In the oviduct |
| What happens over the next few days after a zygote is created? | mitosis (cell division) |
| Why does mitosis take place? | To make more cells |
| What happens after about 5 days from fertilisation? | It becomes a blastocyst which implants itself in the uterus? |
| What is the placenta? | The organ that provides oxygen and food from the mother for the growth of the fetus. |
| What is the uterus? | The muscular organ where the fetus grows and develops. |
| What is the umbilical cord? | A cord connecting the baby to the placenta |
| What is the amniotic sac? | A bag of watery fluid |
| What is amniotic fluid? | Watery fluid protecting the developing fetus. |
| What is the name for factors that can interfere with the normal development of an embryo? | Teratogens |
| What are the four teratogen groups? | chemical agents, infectious agents, physical agents and maternal conditions? |
| What is an example of a chemical teratogen? | Thalidomide - a medication that was used for morning sickness (causes birth defects, many of the babies died within the first year of life) Recreational drugs (reduces blood flow to fetus, miscarriages, bleeding and deaths) |
| What is an example of an infectious teratogen? | Mumps (a viral disease)- causes miscarriages. Listeria (a bacterial disease)- causes miscarriages, premature birth, infection to the newborn |
| What is an example of a physical teratogen? | Radiation - causes mutations and deaths, defects can be passed on to the next generation. Mechanical Forces - causes hip dislocation and deformaties |
| What is an example of a maternal condition teratogen? | Lack of something in diet (for example, iron) - can cause anaemia and stillbirths |
| Why are chromosomes arranged in pairs? | one comes from the mother and one from the father |
| What are some characteristics of someone with Down's Syndrome? | slanting eyes, flattened nose, protruding tongue, thickening of hands and feet and learning difficulties |
| What is different about someone with Down's Syndrome? | The have an extra chromosome in the 21st set. |
| What is a mutation? | a change in the number or structure of chromosomes |
| Why is Down's Syndrome a mutation? | it's a change in the number of chromosomes |
| What are genes? | sections of chromosomes |
| What do genes code for? | different characteristics |
| Why do cells contain two copies of the each gene? | one from the mother, one from the father |
| Each chromosome is a molecule of what? | tightly coiled deoxyribonucleic acid |
| What structure is DNA? | double helix |
| What does Adenine always bond with? | thymine |
| What does cytosine always bond with? | guamine |
| What do DNA bases do? | hold the genetic code |
| What are the rungs of the ladder? | DNA bases |
| What does the age of the mother affect children with Down's Syndrome? | The older the mother, the more common Down's Syndrome is |
| What is the building block of all organisms? | cells |
| What is the nucleus? | the control centre to co-ordinate the cells activities |
| What is each stand of DNA made from? | repeated units called bases |
| What are proteins made from? | repeating units called amino acids |
| The order of amino acids that make a protein is controlled by what? | the order of the bases on the DNA |
