GRADE 12:
LIFE SCIENCES
EXAMINATION HELP
Compiled by: Mrs. S. van Huyssteen
, QUESTION PAPER 1
Topics
1. Reproduction in Vertebrates : 8 marks (5%)
2. Human Reproduction : 41 marks (27%)
3. Reaction on the Environment (humans) : 54 marks (36%)
4. Endocrine and homeostasis (humans) : 34 marks (23%)
5. Reaction on the Environment (plants) : 13 marks (9%)
,1. Reproduction in Vertebrates: ➢ Amniotic egg with extra-embryonic membranes
& functions:
1. CHORION:
➢ Ovipary vs. Vivipary vs. Ovovivipary:
✓ Let O2 in and
OVIPARY:
✓ CO2 through the shell to the outside
→ Internal and external fertilisation
→ Eggs are laid
2. AMNION:
→ Embryo development takes place outside the
✓ Membrane surrounding the amniotic cavity
mother's body
and containing amniotic fluid
→ Disadvantages: ✓ which protects the embryo from mechanical
- Eggs are easy prey for predators injuries.
VIVIPARY: 3. ALLANTOIS:
→ Internal fertilisation ✓ Store waste produced by the embryo
→ Embryo development within the mother's uterus ✓ Also works in gas exchange
→ Receive nutrients from mother placenta
→ Advantages: 4. YOLK SAC:
- Better embryo protection ✓ Nutrition to the embryo
OVOVIVIPARY: 5. SHELL:
→ Internal fertilisation ✓ Prevent dehydration
→ Eggs are kept inside the mother's body ✓ protection
→ Obtain nutrients from the yolk sac
→ Egg hatches inside the mother's body ➢ External and Internal Fertilisation:
→ Then be born alive EXTERNAL:
→ Advantages: → Sperm fertilize egg OUTSIDE female body.
- Greater chance of offspring to be produced → Water is always REQUIRED
- Well-developed offspring are produced → Physical contact is NOT REQUIRED
- Protection against predators → E.g. fish, toad
→ Disadvantages:
➢ Precocial vs. Altricial development: - Chances of fertilization are decreases
PRECOCIAL: - Large amounts of sperm needed
→ Eyes open when they hatch - Zygote is NOT well protected against
→ Body is covered with soft feathers (down) predators
→ Able to move quickly after hatching
→ Able to feed themselves INTERNAL:
→ INDEPENDENT of parents → Sperm are deposited inside the body of the
→ Eggs provide HIGH energy to developing female
embryos → Fertilization takes place WITHIN female
reproductive system
ALTRICIAL: → E.g. birds, mammals
→ Eyes are closed as they hatch → Advantages:
→ Bodies are NOT covered with down - Chances of fertilization are high
→ NOT able to move shortly after hatching - Small amounts of sperm needed
→ NOT able to feed themselves - Zygote WELL protected in female
→ DEPENDENT on parents
→ Eggs provide LESS energy to developing
embryos
, 2. Human Reproduction: → The semen passes through the URETHRA
** NB!! – Male and Female genitals sketches (captions → of the PENIS
textbook p. 5-6) & function textbook pg. 7-9 → to the VAGINA
→ during COPULATION
➢ Structural suitability of the sperm for → and “swim” along the fallopian tube
fertilization: → where it reaches the OVUM.
➢ Oogenesis:
→ Under the influence v. FSH
→ the diploid (germ epithelial) cells divide in the
ovary by MITOSIS
→ to form multiple follicles
→ One cell enlarges in the follicle,
→ and divided by MEIOSIS.
→ Only ONE of the 4 CELLS that are formed
→ Acrosome (G) contains lithic enzymes that cause
SURVIVE.
an opening in the ovum
→ To develop into an adult haploid ovum.
→ Nucleus (F) in the head (H) of the male / haploid
number of chromosomes
➢ Structure & Function of ovum (egg cell):
→ Many mitochondria (D) in the middle part (E)
→ Haploid nucleus that
release energy so that the sperm can swim
→ fuses with the sperm nucleus to form a diploid
→ The presence of a tail (C) makes it possible for the
zygote
sperm cell to swim to the ovum
→ JELLY LAYER that protects ovum
→ The content of the sperm cell, such as the
cytoplasm, is reduced / dense to make the sperm → Causes ovum to become IMPENETRABLE as
cell light for efficient movement soon as FERTILISATION takes place.
→ Sperm is streamlined to allow easy movement → The CYPTOPLASM provides NUTRITION.
(must be able to draw OVUM with labels)
➢ Spermatogenesis and semen formation:
➢ Role of hormones during the menstrual cycle:
• SPERMATOGENESIS:
(ovarian and uterine cycles)
→ Takes place under the influence of
TESTOSTERONE
→ FSH is secreted
→ in the SEMINAL VESICLES in the testes.
→ by the pituitary gland / hypophysis (in the brain).
→ Diploid (germinal epithelium) cells undergo
→ FSH stimulates the development of a primary
MEIOSIS
follicle
→ To form haploid SPERM CELLS.
→ in a Graafian follicle
→ As the Graafian follicle develops, it secretes
• FORMATION + TRANSPORT OF SEMEN:
ESTROGEN
→ Sperm matures and is TEMPORARILY
→ causing the lining of the uterus / endometrium
STORED
→ to thicken/ becomes more vascular
→ in the EPIDIDYMUS.
→ in preparation for possible implantation.
→ During EJACULATION
→ The pituitary gland/ hypophysis
→ sperm move through the VAS DEFERENS
→ secretes LH
→ as it moves through the seminal vesicles
→ which causes the Graafian follicle to break and
→ the PROSTATE gland
release the ovum.
→ and COWPER'S GLANDS
→ This is called OVULATION.
→ adds LIQUIDS which provide NUTRITION
→ The empty follicle changes and forms the corpus
→ and promote MOVEMENT. luteum
→ It NEUTRALIZES ACID produced in the → that start to secrete PROGESTERONE
vagina & urethra.
LIFE SCIENCES
EXAMINATION HELP
Compiled by: Mrs. S. van Huyssteen
, QUESTION PAPER 1
Topics
1. Reproduction in Vertebrates : 8 marks (5%)
2. Human Reproduction : 41 marks (27%)
3. Reaction on the Environment (humans) : 54 marks (36%)
4. Endocrine and homeostasis (humans) : 34 marks (23%)
5. Reaction on the Environment (plants) : 13 marks (9%)
,1. Reproduction in Vertebrates: ➢ Amniotic egg with extra-embryonic membranes
& functions:
1. CHORION:
➢ Ovipary vs. Vivipary vs. Ovovivipary:
✓ Let O2 in and
OVIPARY:
✓ CO2 through the shell to the outside
→ Internal and external fertilisation
→ Eggs are laid
2. AMNION:
→ Embryo development takes place outside the
✓ Membrane surrounding the amniotic cavity
mother's body
and containing amniotic fluid
→ Disadvantages: ✓ which protects the embryo from mechanical
- Eggs are easy prey for predators injuries.
VIVIPARY: 3. ALLANTOIS:
→ Internal fertilisation ✓ Store waste produced by the embryo
→ Embryo development within the mother's uterus ✓ Also works in gas exchange
→ Receive nutrients from mother placenta
→ Advantages: 4. YOLK SAC:
- Better embryo protection ✓ Nutrition to the embryo
OVOVIVIPARY: 5. SHELL:
→ Internal fertilisation ✓ Prevent dehydration
→ Eggs are kept inside the mother's body ✓ protection
→ Obtain nutrients from the yolk sac
→ Egg hatches inside the mother's body ➢ External and Internal Fertilisation:
→ Then be born alive EXTERNAL:
→ Advantages: → Sperm fertilize egg OUTSIDE female body.
- Greater chance of offspring to be produced → Water is always REQUIRED
- Well-developed offspring are produced → Physical contact is NOT REQUIRED
- Protection against predators → E.g. fish, toad
→ Disadvantages:
➢ Precocial vs. Altricial development: - Chances of fertilization are decreases
PRECOCIAL: - Large amounts of sperm needed
→ Eyes open when they hatch - Zygote is NOT well protected against
→ Body is covered with soft feathers (down) predators
→ Able to move quickly after hatching
→ Able to feed themselves INTERNAL:
→ INDEPENDENT of parents → Sperm are deposited inside the body of the
→ Eggs provide HIGH energy to developing female
embryos → Fertilization takes place WITHIN female
reproductive system
ALTRICIAL: → E.g. birds, mammals
→ Eyes are closed as they hatch → Advantages:
→ Bodies are NOT covered with down - Chances of fertilization are high
→ NOT able to move shortly after hatching - Small amounts of sperm needed
→ NOT able to feed themselves - Zygote WELL protected in female
→ DEPENDENT on parents
→ Eggs provide LESS energy to developing
embryos
, 2. Human Reproduction: → The semen passes through the URETHRA
** NB!! – Male and Female genitals sketches (captions → of the PENIS
textbook p. 5-6) & function textbook pg. 7-9 → to the VAGINA
→ during COPULATION
➢ Structural suitability of the sperm for → and “swim” along the fallopian tube
fertilization: → where it reaches the OVUM.
➢ Oogenesis:
→ Under the influence v. FSH
→ the diploid (germ epithelial) cells divide in the
ovary by MITOSIS
→ to form multiple follicles
→ One cell enlarges in the follicle,
→ and divided by MEIOSIS.
→ Only ONE of the 4 CELLS that are formed
→ Acrosome (G) contains lithic enzymes that cause
SURVIVE.
an opening in the ovum
→ To develop into an adult haploid ovum.
→ Nucleus (F) in the head (H) of the male / haploid
number of chromosomes
➢ Structure & Function of ovum (egg cell):
→ Many mitochondria (D) in the middle part (E)
→ Haploid nucleus that
release energy so that the sperm can swim
→ fuses with the sperm nucleus to form a diploid
→ The presence of a tail (C) makes it possible for the
zygote
sperm cell to swim to the ovum
→ JELLY LAYER that protects ovum
→ The content of the sperm cell, such as the
cytoplasm, is reduced / dense to make the sperm → Causes ovum to become IMPENETRABLE as
cell light for efficient movement soon as FERTILISATION takes place.
→ Sperm is streamlined to allow easy movement → The CYPTOPLASM provides NUTRITION.
(must be able to draw OVUM with labels)
➢ Spermatogenesis and semen formation:
➢ Role of hormones during the menstrual cycle:
• SPERMATOGENESIS:
(ovarian and uterine cycles)
→ Takes place under the influence of
TESTOSTERONE
→ FSH is secreted
→ in the SEMINAL VESICLES in the testes.
→ by the pituitary gland / hypophysis (in the brain).
→ Diploid (germinal epithelium) cells undergo
→ FSH stimulates the development of a primary
MEIOSIS
follicle
→ To form haploid SPERM CELLS.
→ in a Graafian follicle
→ As the Graafian follicle develops, it secretes
• FORMATION + TRANSPORT OF SEMEN:
ESTROGEN
→ Sperm matures and is TEMPORARILY
→ causing the lining of the uterus / endometrium
STORED
→ to thicken/ becomes more vascular
→ in the EPIDIDYMUS.
→ in preparation for possible implantation.
→ During EJACULATION
→ The pituitary gland/ hypophysis
→ sperm move through the VAS DEFERENS
→ secretes LH
→ as it moves through the seminal vesicles
→ which causes the Graafian follicle to break and
→ the PROSTATE gland
release the ovum.
→ and COWPER'S GLANDS
→ This is called OVULATION.
→ adds LIQUIDS which provide NUTRITION
→ The empty follicle changes and forms the corpus
→ and promote MOVEMENT. luteum
→ It NEUTRALIZES ACID produced in the → that start to secrete PROGESTERONE
vagina & urethra.
