What does DNA stand for? Deoxyribonucleic acid

Why is DNA important to cell functioning? codes for structural proteins and enzymes which control chemical reactions and therefore determines our characteristics

What do we call the repeating units making up a DNA molecule? nucleotides

The order of these repeating units is very important for the genetic code. What type of molecule do the specific order of units code for? Hint: these molecules become enzymes and building structures within cells. Amino acids→proteins

(d)

3. Why does the DNA have to replicate? Copies of each DNA molecule must be passed onto the

Explain the complementary base pair rule. cytosine only binds with guanine; thymine only binds with adenine

daughter cells during cell division

4. Distinguish between a chromosome and a chromatid. Chromatids are identical copies of DNA molecules that make up a double-stranded chromosome. Chromosomes can be either single stranded or double-stranded

5. Use the diagram below to answer the following questions about mitosis.

(a) What is mitosis? Division of the nucleus during cell division to produce 2 identical daughter

cells

Is interphase a part of mitosis? NO What events happen during interphase. DNA replicates, cell organelles replicate

Diploid number of parent cell = 2 Diploid number of the daughter cells = 2

8. a) Why is reproduction important? To ensure the survival of the species

b) What are the 2 types of reproduction and describe how they differ from one another.

Asexual: only ONE parent; offspring are identical to parents, little energy required (to find mates, have reproductive structures)

Sexual: two parents, offspring have characteristics of both parents, energy required for mate attraction/courtship, reproductive structures and sex cell formation

9. Distinguish between simple/binary fission, budding and parthenogenesis. All are types of asexual reproduction in animals.

Binary fission: single-celled organism dividing into 2 identical (daughter) cells.

Budding: small growth begins to grow off the adult, which then develops into a small version of

the adult. Then pinches off e.g. Hydra

Parthenogenesis: development of unfertilised ovum into individual ie haploid cell  haploid adult

10. a)

List and describe briefly the different forms of vegetative propagation. Give an example for each.

Runners: horizontal stems above ground which put down roots intermittently e.g. strawberries

Rhizomes: horizontal stems below ground e.g. grass

Bulbs: modified compact leaves e.g. onion, garlic

b) What is the advantage of vegetative reproduction for a plant?

Large numbers of identical offspring produced quickly

11. (a)

(b) Where does meiosis occur in plants? Anther and ovary

What is meiosis? Type of cell division producing 4, haploid daughter cells

Where does meiosis occur in animals? Testis and ovary

Identify the structure where fertilisation takes place. fallopian tube (nearer to ovary than uterus)

(c) Identify the structure where implantation takes place. Uterus

FALLOPIAN TUBE: Transfers ovum from ovary to uterus, Site of fertilisation

OVARY: Site of ova and Oestrogen & progesterone (female sex hormones) production,

UTERUS: Where foetus develops, Site of implantation of embryo,

VAGINA: Birth canal for foetus, Site of deposition of sperm by penis

CERVIX:Directs sperm from vagina to uterus, Allows menstrual flow from uterus to vagina