1. Human, Animal, and Plant Reproduction

2. Fertilization
Fertilization is the fusion of a haploid sperm and a haploid egg
Produces a diploid zygote
External fertilization occurs outside the female’s body
This is seen in fish and amphibians
Because of the lack of protection and the harsh environment, many eggs are released to ensure the species’ survival

3. Internal fertilization occurs inside the female’s reproductive tract
This is seen in birds, reptiles, and mammals

4. Embryonic Development
After fertilization, the zygote begins to go through mitosis rapidly
The rapid mitotic divisions are called cleavage
The zygote does not grow much in size, but grows in cell number
At first, cleavage creates a mass of cells called a morula
The morula becomes a ring of hundreds of cells called a blastula

5. The center of the blastula is filled with a fluid, and is called the blastocoel
The blastula then goes through gastrulation, in which it becomes indented
The indented blastula is now called a gastrula, and has two layers
The outer layer is the ectoderm, and the inner layer is the endoderm
A third layer called the mesoderm forms between the ectoderm and the endoderm
The gastrula is now an embryo

6. ectoderm
mesoderm
endoderm
sperm
blastula
gastrula
egg
morula
Cleavage starts
Gastrulation
Embryo
Fertilization

8. Differentiation
In differentiation, the cells of the embryo become specific body cells
This is done by expressing certain genes and not expressing others
The ectoderm becomes the nervous system and skin
The mesoderm becomes the muscles, circulatory system, skeleton, excretory system, and reproductive system

9. The endoderm becomes the lining of the digestive system and respiratory system, parts of the liver, and parts of the pancreas

10. Site of Development
If fertilization was external, development will be external
Ex: fish embryos develop in the water
Survival rate is very low, so many eggs are fertilized
The embryos’ food source is the yolk of the egg
Birds and reptiles have internal fertilization, but external development
Their embryos feed on yolk as well

11. Their eggs have developed a shell for protection and membranes that provide a favorable environment for development
Embryonic membranes:
1. Amnion: contains the amniotic fluid that provides a watery environment, protects the embryo from shock, and prevents the embryo from sticking to the shell
2. Yolk sac: surrounds the yolk and contains blood vessels that transport food to the embryo
3. Allantois: a respiratory membrane and a storage site for nitrogenous wastes like urea

12. 4. Chorion: an outer membrane that surrounds the other membranes

13. Internal development occurs when the embryo grows inside of the body of the female
The parent provides nutrition and protection
There is a relatively high survival rate, so fewer eggs are fertilized

14. Placental Mammals Have internal fertilization and internal development
The embryo develops inside the uterus
The eggs have very little yolk and are small compared to the eggs of other animals
The placenta forms inside the uterus from both embryonic tissues and maternal tissues
The placenta allows for the exchange of nutrients, wastes, and respiratory gases between the mother and the embryo

15. The mother’s blood and the embryo’s blood never mix
Instead, materials are transported by diffusion and active transport
The umbilical cord, which contains blood vessels, connects the embryo to the placenta
Humans are placental mammals

17. Marsupials Marsupials are non-placental mammals
Have internal fertilization and internal embryonic development
Nutrition for embryonic development does not come directly from the mother
The embryo lives off the yolk
The embryo is born prematurely and completes its development in the mother’s pouch
The pouch contains the milk-producing mammary glands

18. Human Gamete Production
Human gametes are made in the gonads
Testes in males
Ovaries in females
Male gametes are sperm
Female gametes are eggs or ova
Both gametes are made in meiosis
Spermatogenesis is the production of sperm
Oogenesis is the production of ova

19. In spermatogenesis, four sperm are made each time meiosis is done
In oogenesis, one ovum and three small polar bodies are made each time meiosis is done
The ovum is large enough to support embryonic growth
The polar bodies disintegrate

20. Male Reproductive System
The testes are located in the scrotum outside the body
Sperm production occurs best at 1-2 degrees below normal body temperature
From the testes, the sperm move through tubes called the vas deferens to the urethra
The urethra is contained within the penis
The penis allows for internal fertlization

21. The prostate gland, bulbourethral gland, and seminal vesicles produce liquid for the sperm as they travel through the vas deferens
The liquid makes semen, which nourishes the sperm and provides a watery environment for them to move through
The testes also produce the hormone testosterone
Testosterone regulates the maturation of sperm and the development of secondary sexual characteristics

22. Seminal vesicle
Vas deferens
Penis
Prostate gland
Urethra
Bulbourethral gland
Vas deferens
Epididymis
Scrotum
Testis

24. Female Reproductive System
The ovaries produce ova in tiny cavities called follicles
The ovum is released from the ovary in ovulation and enters one of the two Fallopian tubes (oviducts)
The uterus is where an embryo will develop
The cervix is the opening of the uterus into the vagina or birth canal

25. The ovaries produce the hormones estrogen and progesterone
These hormones regulate the menstrual cycle and the development of secondary sexual characteristics

26. Uterus
Urinary bladder
Oviduct
Ovary
Cervix
Vagina
Urethra
Vaginal opening

28. Menstrual Cycle
At birth, all the ova a female will ever produce are already present in an immature form
The menstrual cycle will begin at puberty and stop at menopause
The menstrual cycle is the rise and fall of hormones that regulate the release of one ovum every 28 days
Also regulates the preparation of the uterus for pregnancy by thickening the lining of the uterus, called the endometrium

29. 1. Follicle stage: the ovum matures in the ovary, and estrogen is released
Estrogen causes the endometrium to thicken and become more vascularized
2. Ovulation: the ovum is released from the follicle and enters the Fallopian tube
Midpoint of the cycle = day 14
3. Corpus luteum stage: the empty follicle in the ovary becomes the corpus luteum
The corpus luteum releases progesterone, which increases the thickening of the endometrium
4. Menstruation: the shedding of the endometrium that occurs if fertilization does not take place

30. During the menstrual cycle, the hypothalamus in the brain and the pituitary gland also produce hormones
Follicle-stimulating hormone (FSH) causes follicle growth in the ovary and estrogen production
Estrogen production will eventually inhibit FSH
Luteinizing hormone (LH) causes the growth of the corpus luteum and the production of progesterone
Progesterone production will eventually inhibit estrogen, LH, and FSH

31. This regulation of hormones between the pituitary, hypothalamus, and ovaries is an example of negative feedback

32. releases progesterone maintains uterus lining
produces estrogen

33. LH
FSH
ovulation = egg release
egg development
corpus luteum
estrogen
progesterone
days 7 14 21 28

34. Fertilization and Development
Fertilization occurs in the upper one third of the Fallopian tube
If the ovum is not fertilized about 24 hours after ovulation, it deteriorates
If fertilization does occur, the zygote goes through cleavage and travels to the uterus
Takes about 6-10 days to reach the uterus
The zygote is an embryo by the time it reaches the uterus and has depleted its yolk supply

36. In the uterus, the embryo implants in the thick endometrium and can get nutrients from the mother
If more than one ovum was released and fertilized, fraternal twins develop
No more alike than other siblings
If one zygote separates into two during cleavage, identical twins develop
Have the same DNA
In in vitro fertilization, the sperm and ovum are fused in the lab and then inserted into the mother’s uterus
Used when there is trouble conceiving naturally

37. Prenatal Development Cleavage occurs in the Fallopian tube
Gastrulation occurs after the embryo has implanted
Differentiation and growth occur
The placenta is the connection between mother and embryo
The amnion surrounds the embryo and contains the amniotic fluid
The umbilical cord holds the blood vessels that carry materials between mother and embryo

38. 4 weeks
7 weeks

39. 10 weeks

40. 12 weeks
20 weeks

41. Prenatal development requires the supplying of a proper balance of nutrients to the embryo
Harmful substances like alcohol, tobacco smoke, drugs, and infections can travel through the placenta and harm the fetus
Can lead to life-long health problems for the fetus

42. Birth Birth occurs after a nine-month gestation period
Strong contractions of the uterus (labor) force the baby through the cervix and vagina
The placenta is forced out of the body after the baby is delivered
The mammary glands will provide milk for nourishment and antibodies for immunity

43. Intestine
Placenta
Umbilical
cord
Wall of
uterus
Bladder
Cervix
Vagina

44. Asexual Plant Reproduction
In vegetative propagation, a new plant grows out of a part from an old plant
Similar to budding
People often cut stems from plants with desired traits and grow identical plants from those cuttings
Ex: a twig from an apple tree can be used to produce clones of the original tree

45. Parts of the Flower
Meiosis and fertilization take place in the flower of the plant
The flower is specialized for sexual reproduction
The male part of the flower is the stamen
The female part of the flower is the pistil
Flowers with both stamens and pistils are complete flowers
Flowers than have either stamens or pistils are incomplete flowers

46. The stamen is made of the anther and the filament
The anther produces the haploid pollen grains
The pistil is made of the stigma, style, and ovary
The ovule that develops in the ovary contains the haploid egg

48. Pollination
Pollination is the transfer of pollen grains from the anther to the stigma
This can be done using the wind, insects, and birds
Colored petals and nectar attract pollinating insects
Self-pollination is the transfer of pollen from the anther to the pistil of the same flower or same plant

49. Pollen grains have thick walls to prevent dehydration as they travel
Cross-pollination is the transfer of pollen from the anther of one plant to the pistil of another plant
Increases genetic diversity
Pollen grains have thick walls to prevent dehydration as they travel
After pollination, the pollen grain germinates on the stigma and forms a pollen tube
The pollen tube travels down the stigma and into the ovule
Sperm nuclei are made and fuse with the egg

50. Embryo Development
After fertilization, the ovule that contains the embryo develops into a seed
The seed is made of a seed coat and the embryo
The ovary develops into a fruit
The plant embryo has three parts:
1. Hypocotyl: becomes the root and the lower stem
2. Epicotyl: becomes the leaves and the upper stem

51. 3. Cotyledons: contain stored food that will provide nutrition for the germinating plant
If a plant has one cotyledon, it is a monocot
If a plant has two cotyledons, it is a dicot

53. Germination and Growth
Seeds develop in fruit, which aid in seed dispersal
After dispersal, the seeds will germinate if the conditions are right
Sufficient moisture, proper temperature, and sufficient oxygen
After developing into a plant, growth continues at the meristems
Apical meristems are found at the tips of roots and stems and cause an increase in length

54. Lateral meristems are found within the stem and cause the plant to grow wider
The meristems allow the plant to develop all its tissues and organs