DNA

Question 1

DNA

Answer 1

Makes up chromosomes in nucleus in nearly all the cells
Double stranded
Phosphate group, sugar molecule, nitrogen base, ATCG
Double helix
Hydrogen bonds keep strands together

Question 2

Function of DNA

Answer 2

3bases=1amino acid
1gene=1protein
Many triplets= 1gene
Determines which proteins are made and reactions are catalysed

Question 3

DNA replication

Answer 3

Polynucleotide strands of DNA separate
Each strand, template for new DNA strand
Polymerase assembles nucleotides into 2 new strands with base pair rule
2 DNA strands formed

Question 4

Mitosis

Answer 4

Diploid cell
Spindle fibres form
Chromosomes shorten and thicken, replicate, chromatids
Chromatids line up on equator
Chromatids pulled to either end of cell with spindle fibres
Spindle fibres disappear, nucleus reappears, cell divides
Genetically identical

Question 5

Meiosis

Answer 5

Chromosomes shorten, thicken, chromatids
Homologous chromosomes associate, line up on either side of the equator
Hchromosomes pulled to either end of cell, spindle fibres
Nucleus temporarily reforms
Chromatids line up on equator, pulled by spindle fibres
4 haploid cells

Question 6

Cell division Mitosis

Answer 6

Growth, repair of somatic cells
Diploid
Asexual
Genetically identical

Question 7

Cell division Meiosis

Answer 7

Formation of gametes
Haploid
Genetically unidentical
Sexual

Question 8

Fertilisation

Answer 8

Semen released at cervix
Egg lifespan, 3 days
Sperm lifespan, 5 days
Enzymes from acrysome, fertilisation membrane forms when sperm penetrates egg
Nuclei fuse, diploid

Question 9

Implantation

Answer 9

Zygote, after fertilisation
Mitosis, after fertilisation
Embryo, after cell division
Foetus, 8 weeks after fertilisation

Question 10

Placenta, to baby

Answer 10

O2
 Glucose
Amino acids
Vitamins, minerals
Antibodies, antibiotics
Alcohol, nicotine, drugs
Bacteria, viruses

Question 11

Placenta, to mother

Answer 11

CO2, urea

Question 12

Amnion

Answer 12

Thin strong sac
Secretes amniotic fluid
Supports, protects from mechanical shock

Question 13

Birth

Answer 13

40 weeks after fertilisation
Weeks before, head downwards
Contractions, grow in strength, cause amniotic sac to burst
Cervix. 10 cm, contractions change to push baby out
Placenta also delivered

Question 14

Feeding baby

Answer 14

Progesterone and oestrogen cause milk producing tissue to grow
After birth, tissue produces milk
Milk, protein, fat, lactose, antibodies, minerals, vitamins
Mother, eat more lipids, protein

Question 15

FSH

Answer 15

Follicles develop
Sperm production
Oestrogen production

Question 16

Oestrogen

Answer 16

Repair uterus lining

LH production

Question 17

LH

Answer 17

Ovulation
Progesterone production
Testosterone production

Question 18

Progesterone

Answer 18

Uterus lining maintained, for fertilised egg

Inhibits FSH production

Question 19

Puberty, male

Answer 19

Hair growth
Voice deepens
Shoulders widen
Penis grows
Sex drive develops

Question 20

Puberty, females

Answer 20

Hair growth
Hips widen
Menstruation
Breasts develop
Voice deepens
Sex drive develops
Development of sex organs