CT2

Question 1

Diffusion

Answer 1

An overall movement of particles from an area of higher concentration to an area of lower concentration.

Question 2

Concentration gradient

Answer 2

A difference between two concentrations. Particles diffuse down a concentration gradient.
The bigger the difference of concentrations, the steeper the gradient and faster the diffusion occurs.

Question 3

What does diffusion allow?

Answer 3

Small molecules (such as oxygen and carbon dioxide) to move in and out of cells.

Question 4

Partially permeable (semi-permeable) membrane

Answer 4

A membrane that allows some molecules through it and not others.

Question 5

Osmosis

Answer 5

Diffusion of small molecules of a solvent, such as water, through a semi-permeable membrane. The overall movement of solvent molecules will stop when the concentration of solutes is the same on both sides of a membrane.

Question 6

What can osmosis cause?

Answer 6

Tissues to gain or lose mass.

Question 7

How do you calculate mass change?

Answer 7

(Final Mass - Initial Mass) / Initial Mass x 100

A negative answer is a % loss in mass

Question 8

Active transport

Answer 8

Cells transporting molecules against a concentration gradient, or transport molecules which are too big to diffuse through the cell membrane

Question 9

How is active transport carried out?

Answer 9

By transporting proteins in cell membranes. The transport proteins capture certain molecules and carry them across the cell membrane. This is an active process and so requires energy.

Question 10

What kind of processes are osmosis and diffusion?

Answer 10

They are passive processes so they do not require an input of energy.

Question 11

What are sex chromosones?

Answer 11

2 chromosomes that determine what sex you are.

Question 12

What sex chromosomes do females have?

Answer 12

XX

Question 13

What sex chromosomes do males have?

Answer 13

XY

Question 14

What are punnett squares?

Answer 14

They are diagrams that show another way to demonstrate inheritance. The boxes show the possible genotypes.

Question 15

What are punnett squares used for?

Answer 15

To work out the theoretical probability of offspring inheriting certain genotypes.
They are also used to work out the probability of different phenotypes caused by alleles.

Question 16

Heterozygous

Answer 16

You have one recessive allele and one dominant allele.

Question 17

Homozygous

Answer 17

You either have 2 dominant alleles or 2 recessive alleles.

Question 18

Why must people be given the right blood type?

Answer 18

The blood that they are given must be of the right type otherwise the red blood cells in it will clump together, which can kill.

Question 19

How do you classify different types of blood?

Answer 19

Blood is classified in the ABO blood group system. In this system, everyone’s blood is in one of the 4 groups A, B, AB and O.

Question 20

How do you determine which blood group you have?

Answer 20

Which blood type you have is determined by certain “marker molecules” on the outside of your red blood cells.

Question 21

Which of the markers are dominant and recessive?

Answer 21

Allele O is recessive to both A and B however a person with genotype AB shows the affect of both alleles.

Question 22

Codominant

Answer 22

When both alleles for a gene affect the phenotype.

Question 23

How are most human characteristics controlled?

Answer 23

By many genes, not just one. For example several genes affect eye colour in humans, however most variation in eye colour is caused by the OCA2 gene

Question 24

Melanin

Answer 24

A protein that makes hair, eyes and skin darker in colour. Blue iris contains little melanin, while a brown iris contains a lot.

Question 25

Mutation

Answer 25

A change in a gene that creates a new allele. They happen when there is a mistake in copying DNA in cell division.

Question 26

The human genome project

Answer 26

In 2003 the first complete human genome was decoded. The project produced a map of 3.3 billion complementary base pairs in one set of 46 human chromosomes.

Question 27

What can mapping a person’s genome show?

Answer 27

It can indicate their risk of developing diseases that are caused by different alleles of genes.

Question 28

What is genetic variation?

Answer 28

Difference between individuals of the same species as a result of the variation of their genes.

Question 29

How is genetic variation caused?

Answer 29

By the different alleles inherited during sexual reproduction. Different alleles are produced by mutations, some of which can cause changes in the phenotype.

Question 30

Environmental variation

Answer 30

Characteristics affected by their surroundings, for example, how well plants grow is affected by how much light, water and nutrients it gets.

Question 31

Acquired characteristics

Answer 31

Characteristics that are changed by the environment during the life of the individual. Such as piercing your ear.

Question 32

Discontinuous variation

Answer 32

Where the data can only take a limited set of values.

Question 33

Continuous variation

Answer 33

Where the data can be any value in a range

Question 34

Normal distribution

Answer 34

Continuous data for variation often forms a bell shaped curve

Question 35

Binomial system

Answer 35

Using 2 Latin words for naming species

Question 36

Evolution

Answer 36

If the environmental conditions remain changed, natural selection occurs over and over again, and new species evolves with all the individuals having the better adapted variations.

Question 37

How do scientists use fossils to track human evolution?

Answer 37

They work out how old the fossils are and put them in age older. The fossils do not show smooth changes over time because some have not been discovered.

Question 38

What was discovered in 1992?

Answer 38

Scientists discovered some 4.4 million year old fossilised bones from a extinct human like species. More fossils from this species were found and nicked name Ardipithecus Ramidus.

Question 39

Who is Ardi?

Answer 39

Ardi is the most complete set of bones of her species. Ardi was about 1.2m tall and 50kg. Her leg bones show that she may have been able to walk upright. She had very long arms though and very long big toes that stuck out of the sides of her feet and would have allowed her to climb trees.

Question 40

What was discovered in 1974?

Answer 40

Australopithecus Afarensis (nicknamed Lucy). She lived 3.2m years ago and was about 1.07 metres tall. She could probably walk upright. Although her toe bones were arranged in the same way as those of modern humans, they were much more curved.

Question 41

What did Mary and Louis Leakey discover?

Answer 41

They found a more recent human like species in the 1960s. They decided it was closely related to modern humans (homosapiens) and therefore named it Homo Habilis, which translates as handy man.
Homo habilis fossils are 2.4 to 1.4 million years old. The animals were quite short with long arms but walked upright

Question 42

Homo Erectus

Answer 42

Discovered in Asia in the late 19th century and so many scientists thought that humans evolved in Asia. However an almost complete 1.6 million year old skeleton was found by Richard Leakey in 1984 in Kenya. This species was 1.79 metres and strongly built.

Question 43

3.3 million years ago

Answer 43

The earliest evidence of human like animals using stone tools.

Question 44

What did Charles Darwin and Alfred Russel Wallace come up with?

Answer 44

Essentially the same idea about how organisms evolve into each other. The first book about this idea was written by Darwin and published in 1859.

Question 45

Natural selection

Answer 45

By chance the variation of some individuals make them better at coping with change than others and more likely to survive (also called survival of the fittest)

Question 46

Inheritance

Answer 46

The survivors breed and pass on their variations to their offspring so the next generation contains more individuals with the better adapted variation.

Question 47

Resistant

Answer 47

Not affected by

Question 48

What happened with rats in the 1940s and 50s?

Answer 48

Warfarin was used to poison them. When it was first used most rats died but within 10 years most were resistant. Due to the genetic variation there had always been some rats that were resistant. As the poison killed the non-resistant rats, the only rats left to breed were resistant.

Question 49

The pentadactyl limb

Answer 49

Vertebrates have limbs with five fingers.