paper 1 specification 3

Question 1

what are synapses

Answer 1

the connection of two neurons. This is where neurotransmitters diffuse across the gap so they can send then send a new signal to the next neurone.This is very fast but is slowed down at the synapse as it takes time to diffuse

Question 2

what are reflexes

Answer 2

rapid, automatic responses to stimuli that can reduce the chances of injury.The passage of information in a reflex is called the reflex arc

Question 3

name two advantages of sexual reproduction

Answer 3

-produces variation in offspring
-the disease is less likely to affect all individuals

Question 4

name two disadvantages of sexual reproduction

Answer 4

-need to find a mate
-fertilisation takes time

Question 5

name two advantages of asexual reproduction

Answer 5

-don’t need to find a mate
-rapid reproductive cycle

Question 6

what is meiosis

Answer 6

a type of cell division that only happens in the reproductive organs that produce gametes

Question 7

what is DNA

Answer 7

strands of polymers made up of lots of nucleotides that consist of a sugar and phosphate group with one of the four bases attached to the sugar

Question 8

what is fertilisation

Answer 8

a male gamete fusing with a female gamete to produce a fertilised egg known as the zygote

Question 9

how many chromosomes do gametes have

Answer 9

half the number of chromosomes of normal cells as they are haploid

Question 10

what is the structure of DNA

Answer 10

two strands coiled together in the shape of a double helix

Question 11

name two disadvantages of asexual reproduction

Answer 11

-no variation
-selection pressure would affect all individuals

Question 12

what are chromosomes

Answer 12

coiled up lengths of DNA molecules