Summary IEB Grade 12 Notes on life Processes in Plants and Animals
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Course
Life Sciences
Institution
12
Book
Life Sciences
In-depth notes created according to the 2021 IEB SAGS document for matric life sciences. Vital components have been covered. These notes are not only summaries of the strand 2 syllabus, but are the required topics to be studied for the IEB finals and can be used as a study source. Topics in this do...
Diversity of Reproductive
Strategies in Some Animals
Life Processes in Plants and Animals
SAGS List
Candidates should know how reproductive strategies maximise reproductive success
in different environments. [Link to population dynamics]
Study appropriate South African examples to illustrate each of the following:
- Courtship (one example)
- External fertilisation vs internal fertilisation (one example of each)
- Ovipary, ovovivipary and vivipary (one example of each)
- Amniotic egg (one example - no details of structures)
- Parental care (one example)
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,Notes Compiled by Giorgia Lobban (2021)
How Reproductive Strategies Maximise Reproductive Success in
Different Environments
- Reproduction= the production of a new generation from an existing generation.
- Sexual reproduction= reproduction that involves the fusion of gametes to form a zygote.
- Asexual reproduction= reproduction that involves one, single animal.
- Reproductive strategies= the way in which organisms ensure that reproduction is
successful.
The goal of each animal species is to produce the maximum number of offspring while using
the least amount of energy (reproductive effort)
Sexual reproduction is more complex as it involves a higher energy input
Asexual reproduction is more energy efficient and simple
Unique reproductive strategies have developed to ensure maximum reproductive success in
different environments, allowing for greater chances of survival for species
Courtship
Behaviour in animals that is designed to attract another animal for mating or breeding
Simple
Chemical= pheromones
Visual= brightly coloured body parts
Auditory= mating calls to find each other
Example:
- Male birds advertise by singing a species-specific song that attracts a female. Once they
meet, the male must impress the female by special plumage (striking features such as extra-
long tail feathers of widowbirds)
Complex
Unique to species
Females prefer males that are better in every way= larger, more elaborate features, more
energy in courtship activity than other males
Example:
- Certain birds have complex courtship patterns such as extended series of singing, dances by
males and even feeding (blue cranes and African hoopoes)
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, Notes Compiled by Giorgia Lobban (2021)
External Fertilisation vs Internal Fertilisation
Fertilisation is the fusion of the egg with the sperm cell
External Fertilisation Internal Fertilisation
Fertilisation occurs outside the animal’s body Fertilisation occurs inside the animal’s body
Common in aquatic animals and is only possible Common in terrestrial animals
for animals that breed in water
Large number of sperm and eggs are released Fewer eggs and sperm are produced
Some animals ensure the release of sperm and Sperm is in a watery fluid called seminal fluid
eggs occur at the same time (e.g., male frogs and must be directly planted into the vagina for
call to attract mate) fertilisation
Low success rate for fertilisation of all eggs High probability of successful fertilisation
Diagram of external fertilisation in fish
Ovipary, Ovovivipary and Vivipary
Terms for reproductive strategies that describe the moment at which the future offspring
separates from parent
Type of Explanation Example
development
Ovipary Mother lays eggs that hatch outside of her body Fish, reptiles, birds
Ovovivipary Eggs are kept inside mother’s body until they hatch but there is Some shark
no connection between mother and developing embryo. (hammer head)
Purpose is to protect developing embryos from predation and and snake species
dehydration
Vivipary Embryo develops inside the mother and is nourished via the Mammals
placenta until birth
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,Notes Compiled by Giorgia Lobban (2021)
Amniotic Egg
Shelled egg that can survive and develop on land (reptiles and birds)
Chorion
- Works with allantois to allow for gaseous exchange
Yolk sac
- Contains yolk that provides food for developing embryo
Shell
- Protects the egg
- Prevents drying out
- Exchanges gases with the environment
Amnion
- Grows around embryo
- Contains amniotic fluid
Amniotic fluid
- Protects the embryo
Albumin
- Provides embryo with water and protein
Allantois
- Stores waste produced by embryo
- Exchanges gases with the environment
Embryo
- Growing animal
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,Notes Compiled by Giorgia Lobban (2021)
Parental Care
Occurs when parents look after the young once they are born
Offspring with greater independence have higher chance of survival in reproductive ages
Altricial development
Young are born in a helpless condition and need parental care
- Not able to move around
- Vulnerable to predators
- Depend on parents for food, shelter, and protection
Example:
Dogs, cats, humans, etc.
Precocial development
Young are born relatively independent and require little or no parental care
- Able to move independently
- Able to avoid predators
- Not very dependent on parents for shelter, food, and defence
Example:
Chickens, horses, turtles, etc.
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,Notes Compiled by Giorgia Lobban (2021)
Human Endocrine System
Life Processes in Plants and Animals
SAGS List
The nervous system and hormones enable animals to respond to external changes and to
control conditions inside their bodies
Candidates should know:
1. The location of the endocrine glands listed below and the role of the hormones in
body functions. These should be learnt in their context in the FET phase.
- Hypothalamus (ADH), pituitary gland (TSH, FSH, LH, Growth hormone), thyroid
gland (thyroxin), pancreas (insulin & glucagon), adrenal gland (adrenalin), gonads
(testosterone & oestrogen, progesterone). Other reproductive hormones
(oxytocin and prolactin)
And the disorders of the endocrine system: diabetes, thyroid disorders, growth
disorders, infertility.
2. The concept of homeostasis as a means of maintaining a stable internal
environment.
3. The general role of negative feedback in homeostasis, drawing on glucose and
reproductive hormones.
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,Notes Compiled by Giorgia Lobban (2021)
1. The Location of the Endocrine Glands and the Role of the
Hormones in Body Functions
Hypothalamus
Osmoreceptors in the blood vessels of hypothalamus detect increase in osmolarity (low water
levels) and releases ADH.
Location= base of the brain
Hormone= ADH (anti-diuretic hormone)
Target organ= travels to the posterior pituitary gland and then into the blood to the
collecting ducts of the kidney.
Hormone function:
- Makes walls of ducts more permeable
- Allows water to be drawn back into blood (avoid passing out through urine)
- Conserves water
- Urine will be darker in colour and more concentrated
7|Page
, Notes Compiled by Giorgia Lobban (2021)
Pituitary Gland
Also known as the Master Gland as it controls the activities of a number of other endocrine glands.
Location= base of brain, attached to Hypothalamus (controlled by Hypothalamus)
Hormones:
TSH (Thyroid Stimulating Hormone)
Target organ= Thyroid Gland (base of neck)
Function= stimulates thyroid gland to secrete thyroxin, keeping levels in blood constant
FSH (Follicle-stimulating Hormone)
Target organ= ovaries (female); testes (male)
Function= stimulates oogenesis in ovary (formation of eggs); stimulates spermatogenesis
in testes (sperm formation)
LH (Luteinising Hormone)
Target organ= ovaries (female); testes (male)
Function= stimulates ovulation and formation of corpus luteum (from production of
progesterone); testes to produce testosterone
Prolactin (females only)
Target organ= glandular tissue in the breast
Function= milk production after birth of a baby (also responsible for much maternal
instinct)
GH (Growth Hormone)/STH (Somatotrophic Hormone)
Target organ= affects many organs
Function= synthesis of proteins for growth. Has strong effects of growth of liver,
muscles, bone, and cartilage (overall growth)
Disorders:
- Childhood= Dwarfism> hyposecretion (too little GH); Gigantism> hypersecretion (too
much GH
- Adulthood= Acromegaly> hypersecretion (too much GH)
Thyroid Gland
Location= base of neck (across trachea and below larynx)
Hormone= Thyroxin (iodine is essential for production- found in sea food, sea salt, or iodised
water)
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