reproduction n a lil dna

Question 1

Function of sepal

Answer 1

Enclose and protect the bud

the “leaf” thing below flower

Question 2

function of Petals

Answer 2

colourful and fragrant, they attract pollinators to the flower

Question 3

function of Anthers

Answer 3

Sacs where meiosis occurs and pollen grains develop. Pollen grains house the cells that develop into sperm.

Question 4

function of Carpel

Answer 4

Long slender style with sticky stigma for pollen grain deposition.
style+stigma+ovary

Question 5

function of Ovary

Answer 5

Reproductive structures called ovules, containing one developing egg (ovum) and cells that support it.

Question 6

Growth of the pollen tube

Answer 6

Pollen grains germinate in response to sugary fluid produced by mature stigma
A pollen tube grows out of the pollen grain and the male gamete forms in the tube
Pollen tube secretes enzymes to digest stigma and style tissue, growing down style.
Pollen tube enters ovary through micropyle
Tip of the pollen tube absorbs sap and bursts, releasing 2 male gametes.
Nucleus of male gamete fuses with nucleus of ovum to form zygote (fertilisation)

Question 7

Pollination definition

Answer 7

The transfer of pollen grains from anther to stigma by wind or animal

Question 8

Self-pollination definition

Answer 8

transfer of pollen grains from anther to stigma of the same flower or in the same plant

Question 9

Prevent self-pollination

Answer 9

self-incompatibility: Stigma can recognise the pollen of the same flower, pollen grain cannot germinate on stigma of the same plant
Anther ripen first, stigma not ready to receive pollen, so pollen cannot be transferred to stigma of the same plant.

(Male part covering female part and only allow pollination after its own pollen sacs are removed by pollinators)

Question 10

Cross-pollination definition

Answer 10

transfer of pollen grains from anther of one plant to stigma of another of same species.

Question 11

Compare insect vs wind-pollinated

Answer 11

Large, brightly colored petals/Small dull petals
Nectar/No nectar
Fragrant/Odourless

Stigmas are small, compact and do not protrude out of the flower/Stigmas are large feathery and protrude out of the flower (to provide a large surface area to trap pollen)

Stamens are not pendulous and do not stick out of flower/Stamens have long pendulous filaments and protruding anthers (Pollen grains easily shaken out of anthers)

Pollen is abundant/Pollen is very abundant.
Pollen grains are large with rough surface (to cling onto insect body)/Pollen grains have smooth surfaces, tiny and light (to be carried by the wind.)
Nectar guide present on petals for insects/No nectar guide

Question 12

function of Testes

Answer 12

producing testosterone responsible for man’s secondary sexual characteristics, producing sperm

Question 13

function of Scrotum

Answer 13

muscles contract and relax to control temperature for sperm development warmer or cooler by moving closer or further from the main body to 2degrees cooler than body temp, allowing them to function normally.

Question 14

function of sperm ducts

Answer 14

delivers sperm from epididymis to urethra during ejaculation.

Question 15

function of prostate gland

Answer 15

produces fluid that nourishes sperm and provides sperm protection from naturally acidic vagina

Question 16

function of Urethra

Answer 16

conveys at different times, urine and sperm out of body through penis.

Question 17

function of Penis

Answer 17

Deliver sperm to vagina

Question 18

function of Ovaries

Answer 18

produce oestrogen and progesterone, and release eggs in ovulation

Question 19

function of Fallopian tubes

Answer 19

site of fertilisation, cilia sweep ova (eggs/ovums)

Question 20

function of Uterus

Answer 20

thick and muscular wall allow it to grow and expand to several times its original size during pregnancy

(Blood-rich endometrium layer) is where embryo implants to draw nutrients.

Question 21

function of Cervix

Answer 21

allows flow of menstrual blood into the vagina and directs the sperms into the uterus

Question 22

function of Vagina

Answer 22

repository for sperm

Question 23

function of Endometrium

Answer 23

thick and muscular wall allow it to grow and expand to several times its original size during pregnancy
Provides blood-rich endometrium layer for embryo to implant to draw nutrients.

Question 24

Ovary vs testis

Answer 24

Both produce gametes
Ovary is located in the body while testis is located outside the body
All sex cells are produced at birth in the ovary whereas the testis only starts producing sex cells at puberty.

Question 25

Sperm vs egg

Answer 25

Both carry DNA
Size
Motile

Question 26

Given Menstrual cycle, possible days fo fertilisation?

Answer 26

Menstrual cycle begins on day__. (where there are dots) as breakdown of endometrium happens on day__.
Ovulation happens on the 14th day of the menstrual cycle,
Making possible days __ and __ as the egg survives one day after ovulation.

Question 27

Narrate Menstrual cycle

Answer 27

FSH stimulate growth of follicles in ovary (Repair and build-up of endometrium: oestrogen)

Developing follicles secrete oestrogen (stimulates build-up of endometrium, prevents further secretion of FSH) (Negative feedback on the pituitary gland)

High and sudden peak of oestrogen levels stimulate surge in LH and some FSH (Positive feedback on the pituitary gland)

Surge in LH stimulates maturation and rupture of follicles (ovulation)
LH stimulates conversion of follicle tissue to corpus luteum.

Corpus Luteum secretes progesterone and some oestrogen, inhibiting secretion of LH and FSH (continues thickening and maintenance of endometrium) (Negative feedback on the pituitary gland)

Falling levels of LH and FSH cause degeneration of corpus luteum. Progesterone and oestrogen level decrease, endometrium breaks down, menstrual cycle restarts.

Question 28

Describe fertilisation and early development of the zygote simply

Answer 28

formation of a ball of cells which becomes implanted in the wall of the uterus.

Question 29

State the different stages of embryo development from a zygote.

Answer 29

Fertilised embryo secretes human chorionic gonadotropin (hCG), which maintains the corpus luteum, which continues to secrete oestrogen and progesterone, keeping the endometrium intact.
Outer layer of cells of blastocyst form part of the placenta.
Amnion enclose embryo
Embryo develop finger-like chorionic villi on the placenta that help implant embryo to endometrium

Question 30

function of amniotic sac

Answer 30

Protection (cushion from external trauma)
Constant temperature
Free movement for foetal muscle development (and lubrication)
Practice swallowing, feeding

Question 31

function of Plancenta

Answer 31

It has finger-like chorionic villi that increases the surface area to volume ratio for faster diffusion of oxygen and nutrients (and protective antibodies) from maternal blood to foetal blood and diffusion of metabolic waste from foetal blood to maternal blood. (excreted by mother’s kidneys)

Question 32

Umbilical cord definition

Answer 32

circulatory pathway that connects embryo to chorionic villi of the placenta

Question 33

function of Umbilical cord

Answer 33

Transport oxygen and nutrients to the foetus (umbilical vein: oxygenated blood) and waste products from the foetus to the placenta (umbilical artery: deoxygenated blood)

Question 34

Physical, surgical, chemical and behavioural contraception

Answer 34

Physical: Condom, diaphragm
Surgical: Vasectomy, tubal ligation
Chemical: spermicide, IUD, pills
Behavioural contraception: Rhythm method

Question 35

Features of contraception

Answer 35

require a doctor to be administered

do not protect against STIs

Question 36

How IUD works

Answer 36

IUD with copper provokes an immune response against sperm and eggs that destroys them
Hormones on IUD inhibit ovulation,
Effect against implantation

Question 37

How Contraceptive pills works

Answer 37

Contains oestrogen and progesterone
That prevents ovulation by decreasing LH and FSH levels
Low FSH prevents follicle maturation
Low LH prevents ovulation

Question 38

Describe in vitro fertilisation

Answer 38

in vitro fertilisation as the union of an egg and sperm in a laboratory followed by implantation of the zygote into the uterus.

Question 39

Relationship between DNA, genes and chromosomes.

Answer 39

Each chromosome is made up of 1 DNA coiled tightly around a core of histone proteins.
1 DNA is made up of several sections of sequences of nucleotides that result in different genes.
Each gene controls formation of a single polypeptide, determining a phenotype.

Question 40

COMPARE (what elements? in the case of DNA)

Answer 40

Building blocks: peptides vs nucleotides
Elements: CHONS vs CHOPN
Bonds: peptide bonds and phosphodiester bonds
Location: plant storage organ vs animal nucleus

Question 41

role of condensation reactions in joining the components (nucleotides, di-, poly-)

Answer 41

Nucleotide:
nitrogenous base+pentose sugar (deoxyribose sugar)+phosphate group + 2H2O 2 water molecules formed
Dinucleotide: phosphodiester bond: covalent bond between 5’-phosphate group of one nucleotide and 3’OH group of another nucleotide. 1 water molecule is lost in the process.
Polynucleotide: Condensation reactions between the phosphate group of one nucleotide and the sugar group of another nucleotide form nucleic acid (polynucleotide)

Note: Hydrogen bond is not condensation.

Question 42

State and explain rule of complementary base pairing, antiparallel orientation and hydrogen bonding in the formation of DNA double helix.

Answer 42

• A-T (2 hydrogen bonds), C-G (3 hydrogen bonds)
• Antiparallel structure
  DNA is made up of two antiparallel strands of alternating deoxyribose sugar and phosphate groups

Explain: DNA stability

Question 43

Explain how DNA molecule structure contributes to DNA stability

Answer 43

Nucleotides are joined together by strong covalent phosphodiester bonds with one base attached to each sugar molecule along the strand to form the sugar-phosphate backbone, contributing to DNA stability.

Antiparallel(asking structure). It allows for complementary base pairing with two hydrogen bonds formed between A and T and three hydrogen bonds formed between C and G. Hydrogen bonds are formed between complementary bases. Although weak by itself, they provide support to DNA structure collectively.