1 - Reproduction II

Question 1

How does oxygen reach the placenta

Answer 1

Enriched blood arrives via umbilical vein

Question 2

Oxygen to placenta pathway

Answer 2

Passes by liver via ductus venous
Inferior VC —> RA —> LA —> aorta (heart and rest of body) —> superior VC —> RA —> RV 1/3 goes to the lungs (ductus arteriosis to aorta) —> deoxygenated returns returns to placenta by umbilical cord

Question 3

Difference in ductus arteriosus (foetal and newborn)

Answer 3

Foetal - open
Newborn - closed

Question 4

Difference in foraman ovale (foetal and newborn)

Answer 4

Foetal - open
Newborn - closed

Question 5

Stages of Birth

Answer 5

1. Cervix dilation (induced by smooth muscle contractions stimulated by oxytocin), contractions shorten uterus and baby is pushed towards cervix
2. Cardinal stages (delivery)
3. Stringy uterine contractions separate placental and deliver it (blood vessels compressed to reduce bleeding

Question 6

Hormonal lactation

Answer 6

physical stimulation —> hypothalamus stimulates posterior pituitary to release oxytocin which stimulates breast milk production

Question 7

Menopause

Answer 7

reduction in hormone production by ovaries in repsonse to gonadotrophons

(hypothalamic —> pituriaty —> overly axis shuts down)

Question 8

Eggs and reproductive strategies (birds, mammals, some invertebrates)

Answer 8

gamete containing eggs are fertilised by sperm internally (copulation)

Question 9

Eggs and reproductive strategies (invertebrates, fish, amogibians)

Answer 9

release of gamete containing eggs to evironment

Question 10

Different types of eggs - Microelecithal

Answer 10

all eutherian mammals, some marine mammals

(very little or no yolk)

Question 11

Different types of eggs - Centrolecithal

Answer 11

Insects, arthropods, Cnidaria (yolk and haploid germ cell located centrally)

Sperm can only enter at micropyle as chorion (gas exchange via pores)

Question 12

Different types of eggs - Mesolecithal

Answer 12

amphibians and teleost fish (moderate amount of yolk (unevenly distribute

yolk is heavy

collects at vegetal pole lower half

Question 13

Different types of eggs - Macrolecital

Answer 13

birds, reptiles, some mammals

very large amounts of yolk, unevenly distributes, supports embryo development until yolk completely consumed

Question 14

Reproductive strategies - viviparous animals

Answer 14

placenta (eutharian mammals) allows brith of free living young that have developed in the mother

Question 15

Reproductive strategies - Marsupials

Answer 15

with ouch in which young grow in after delivery from uterus, development in uterus is very short

embryo within ‘shell-type egg’

underdeveloped when born

pouch provides protection and access to teats or milk

Question 16

Reproductive strategies - Monotremes

Answer 16

egg laying - no internal connection with mother

after hatching new born take up milk via mammary glands that are openings in the skin

long parental care of young

Question 17

Vertebrates with amnion

Answer 17

Reptiles, birds, mammals

(Amnion is membrane around embryo)

Question 18

Chick embryo

Answer 18

entirely surrounded by amnion

yolk sac provides nutrition

chorion and allantios form vascularised membrane on inside of cell for gas exchange

Question 19

Amniotes and Sperm Diagram on OneNote

Question 20

Acrosome

Answer 20

Derived from Golgi

Contains enzymes that digest proteins and sugars, these enzymes are required to lyse outer coverings of egg

Question 21

Acrosome - nucleus

Answer 21

Contains haploid number of chromosomes

Question 22

Acrosome - midpiece

Answer 22

Contains mitochondria that produce the energy (ATP) required for motility

Question 23

Acrosome - flagellum

Answer 23

Required for sperm propulsion

Motor portion of flagellum is the axoneme

Question 24

Stages of fertilisation

Answer 24

1. Attraction and activation of sperm by contents of female reproductive tract
2. Binding of sperm to zone pellucida
3. Release of enzymes from acrosme to lose hole in zone
4. Passage of sperm through zona
5. Fusion of sperm and oocyte plasma membranes

Question 25

Acrosomal reaction

Answer 25

Triggered by initial contact between sperm and zona pellucida (jelly like coat on surface of the egg) Hydrolysis enzymes released by acrosome generate opening of zona pellucida Plasma membranes of sperm and egg fuse —> syngamy (meiosis) Sperm nucleus enters egg Protective reaction to prevent polyspermy - cortical granulates fuse with plasma membrane to make it impenetrable (cortical reaction)

Question 26

Annelid reproduction

Answer 26

A-sexual and sexual Any 2 earthworms can mate by joining together and fertilising each others eggs, tube of mucus secreted by citellum and forms an egg case which slips off worms body and then hatch out into soil

Question 27

Insect reproduction - parthenogenesis

Answer 27

production of unfertilised eggs which result in female offspring (thekytoky) or male offspring (arrhenotoky - mostly haploid)

Question 28

Insect Reproduction - metamorphosis

Answer 28

insect larva hatches from egg, then change body shape and size to develop into adult insect 3 different types of metamorphosis - incomplete / complete / no metamorphosis

Question 29

Insect reproduction - overview

Answer 29

Mostly oviparous

Question 30

Insect Reproduction - Holonetabolus

Answer 30

Most of larval tissue within the pupa is enzymaticaly digested Imaginal discs arise which organise rapid cell division to form body structures of adult (eyes, legs, wings)

Question 31

Fish reproduction

Answer 31

Fish fertilise eggs externally Large numbers of eggs and sperm released into water (fertilisation by chance)

Question 32

Amphibian Reproduction - overview

Answer 32

External fertilisation (eggs are mesolethical —> laid in water)

Question 33

Amphibian Reproduction - Metamorphosis

Answer 33

Egg encases in gel like mass / hatching tadpole with external gills / metamorphosis into adult amphibian —> growing hung and front legs and resorption of tail

Question 34

Amphibian Reproduction - how is metamorphosis controlled

Answer 34

Metamorphosis controlled by hormones generated by thyroid, which either activate or repress transcription of genes

Question 35

Amphibian Reproduction - Biochemical transformations

Answer 35

Haemoglobin changed from tadpole to adult version Binds to O2 more slowly and releases more rapidly Liver enxymes change to reflect habitat (tadpoles excrete ammonia and adult urea)

Question 36

Mammalian Reproduction - fertility and reproductive cycles

Answer 36

Uterine bleeding if no pregnancy Seasonal or repeated reproductive cycles Spontaneous or stimulated ovulation to release eggs

Question 37

Mammalian Reproduction - Embryonic diapause

Answer 37

Delayed development in stages of pregnancy Determined by environemtal factors and lifestyle

Question 38

Mammalian Reproduction - Lactation

Answer 38

Number of young nursed at same time Mammary gland structure and morphology Duration of lactation Composition of milk Passive immunity

Question 39

Plant Reproduction - Angiosperms

Answer 39

Flowering Plants Flowers attractive pollinators or passive pollination / pollen grows pollen tube / 2 haploid pollen nuclei move down towards ovaries

Question 40

Plant Reproduction - Key Events (meiosis)

Answer 40

Meiosis in both male and females Follwed by mitosis to produce 1/2 haploid gametes and additional support cells

Question 41

Plant Reproduction - Key Events

Answer 41

Pollen with 2 haploid sperm cells Ovule with 1 haploid egg cell and 1 centeral cell with 2 haploid nuce (and additional support cells) 1 sperm cell fuses with haploid egg —> diploid zygote (mitosis) 1 sperm cell fuses with centeral cell

Question 42

Plant Reproduction (gymnosperms)

Answer 42

non flowering plants (conifers, cycads)