this document contains detailed notes on: nucleic acids, evolution, genetics, genetic engineering, human and plant reproduction, reproductive strategies and chemical coordination. these notes are for an IEB syllabus.
THIS DOCUMENT COVERS THE
FOLLOWING SECTIONS:
- plant and human reproduction
- reproductive strategies
- chemical coordination
- nucleic acids
- genetics
- genetic engineering
- evolution
Figure 1: https://www.google.com/url?sa=i
THESE NOTES ARE FOR AN IEB
SYLLABUS AND SHOULD ONLY BE USED
AS SUPPLEMENTARY NOTES TO YOUR
BIOLOGY NOTES: SCHOOL TEXTBOOK.
Grade 12
,Contents
Human reproduction: ........................................................................................................................ 3
Male reproductive system: ............................................................................................................ 3
Puberty in boys:............................................................................................................................. 4
The female reproductive system:................................................................................................... 5
Puberty in girls: ............................................................................................................................. 6
Gametogenesis: ............................................................................................................................. 6
Structure of a sperm cell: ............................................................................................................... 6
Development of the ovum in the ovary: ......................................................................................... 7
The menstrual cycle ....................................................................................................................... 8
Fertilization: .................................................................................................................................. 8
Hormones of implantation:............................................................................................................ 9
Gestation: parts of the placenta .................................................................................................. 10
Functions of the placenta: ........................................................................................................... 10
Contraception: ............................................................................................................................ 11
Plant Reproduction:......................................................................................................................... 13
The structure of a flower: ............................................................................................................ 13
Pollination agents: ....................................................................................................................... 14
Fertilization: ................................................................................................................................ 14
Asexual reproduction in plants: ................................................................................................... 15
Reproductive strategies: .................................................................................................................. 16
Courtship:.................................................................................................................................... 16
Amniotic egg: ....................................................................................................................... 17
Parental care: .............................................................................................................................. 18
Survival strategies:....................................................................................................................... 18
Survivorship curve: ...................................................................................................................... 18
Mendel: ....................................................................................................................................... 19
Mendel’s laws: ............................................................................................................................ 20
Genetics Terminology: ................................................................................................................. 20
chemical coordination: .................................................................................................................... 21
coordinating systems: .................................................................................................................. 21
Functions controlled by hormones:.............................................................................................. 21
The posterior pituitary gland: ...................................................................................................... 22
The anterior pituitary .................................................................................................................. 22
the thyroid gland: ........................................................................................................................ 23
1
, Functions of thyroxin: .................................................................................................................. 24
Disorders of the thyroid gland: .................................................................................................... 24
Negative feedback control of thyroxine production: .................................................................... 25
Pancreas: ..................................................................................................................................... 25
What does Glucagon do? ............................................................................................................. 25
What does insulin do? ................................................................................................................. 25
Disorders of the pancreas: ........................................................................................................... 26
Adrenal glands:............................................................................................................................ 26
Reproductive organs:................................................................................................................... 27
Genetic engineering: ....................................................................................................................... 28
artificial selection: ....................................................................................................................... 28
Genetic engineering/modification: .............................................................................................. 28
CRISPR-cas9: ................................................................................................................................ 28
Ethical implications of CRISPR Cas9: ............................................................................................. 29
Gene therapy:.............................................................................................................................. 30
Cloning: ....................................................................................................................................... 30
Cloning in plants: ......................................................................................................................... 31
Evolution: ........................................................................................................................................ 32
Patterns of macroevolution: ........................................................................................................ 32
Rates of evolutionary change:...................................................................................................... 33
Evidence for the theory of macroevolution: ................................................................................. 33
The development of the theory of evolution:............................................................................... 34
Darwin's theories:........................................................................................................................ 35
Mechanisms of Speciation: .......................................................................................................... 35
Evolution terminology: ................................................................................................................ 35
nucleic acids: ................................................................................................................................... 37
Diagram of DNA:.......................................................................................................................... 38
Diagram of RNA: .......................................................................................................................... 38
Mitochondrial DNA: ..................................................................................................................... 39
Proteins: ...................................................................................................................................... 39
Protein synthesis: ........................................................................................................................ 39
Mutations: ................................................................................................................................... 40
DNA replication: .......................................................................................................................... 41
Polymerase chain reaction: .......................................................................................................... 41
2
, Human reproduction:
Male reproductive system:
1. The testes
- They are situated outside of the abdominal cavity for optimal temperature to produce
sperm.
- Inside a double layered pouch known as the scrotum.
- Each testis is divided into compartments known as lobules.
- Lobules contain tubules, known as; seminiferous tubules which are lined with germinal
epithelium. These specialised cells divide by mitosis and then meiosis to form haploid
spermatozoa
- Spermatogenesis: the process of sperm production.
- Men produce between 200-500 million sperm each ejaculation and can produce sperm
for their entire lives.
- Some of the Germinal epithelium cells divide into Sertoli cells (columnar cells), these
provide nourishment for developing sperm cells.
- Interstitial cells: these cells lie in between the seminiferous tubules, these produce
testosterone.
2. The epididymis
- Seminiferous tubules open into the epididymis,
- This is where sperm is stored between ejaculations, this is where the sperm matures.
- The epididymis forms the vas deferens.
3. The scrotum
- In the male foetus, the testis form inside the abdominal cavity and then descend to the
scrotum by the time of birth.
- The scrotum is very important as it allows for the testes to be at an optimal temperature
for sperm production which is lower than body temperature, this optimal temperature is
34 degrees Celsius.
4. The Vas deferens
- Passes through the abdominal cavity and opens into the urethra.
- The vas deferens uses peristaltic movement to transport sperm.
- The urethra carries both sperm and urine to the penis and out of the body.
- The end of the vas deferens are known as ampulla.
3
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