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ALL Chapters Grade 12 LIFE Sciences Notes 1 045329
Life Sciences (Wyebank Secondary School)
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1 for 2022 SH
PAPER 1
Marks: 150
Time: 2½ hours
Learners must answer all 3 questions.
TOPICS MARKS PAGE
1. Reproduction in vertebrates ……………………………………….. 8 35
2. Human reproduction ……………………………………………...... 41 37
3. Responding to the environment (humans) ………………………. 54 42
4. Human endocrine system and Homeostasis ……………………. 34 52
5. Responding to the environment (plants) …………………………. 13 59
PAPER 2
Marks: 150
Time: 2½ hours
Learners must answer all 3 questions.
TOPICS MARKS PAGE
1. DNA: Code of life ……………………………………….…............. 27 2
2. Meiosis ………………..…………………………………………...... 21 7
3. Genetics and inheritance ………………………………………….. 48 13
4. Evolution ……………………………………………........................ 54 22
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DNA: CODE OF LIFE (27 marks) REMEMBER
Nucleic acids Nucleus,
ribosome and
Two types: - DNA (Deoxyribonucleic acid) and
mitochondria are
- RNA (Ribonucleic acid)
organelles
- Both DNA and RNA made up of nucleotides
DNA (monomers or building blocks of DNA and RNA)
Location:
- In the nucleus: Nuclear DNA
Make up most of the DNA
Works with proteins to form chromatin network or chromosomes
- In the mitochondria: Mitochondrial DNA (mtDNA)
Extranuclear DNA is DNA found outside nucleus eg mtDNA
Structure of DNA: https://www.youtube.com/watch?v=C1CRrtkWwu0
- DNA is a nucleic acid
- It is double stranded
- natural shape of DNA is double helix
- consisting of building blocks called nucleotides
- The three components of a nucleotide are as follows:
• Phosphate portion (P)
• Deoxyribose sugar (S) portion (in DNA)
• 4 Nitrogenous bases are Adenine (A),
Thymine(T), Cytosine(C) and Guanine(G)
o adenine always bonds with thymine (A)=(T)
o cytosine always bonds with guanine (C)=(G)
o by weak hydrogen bonds
Functions of DNA
- Sections of DNA forms genes that carry hereditary information
- DNA contains coded information for protein synthesis
RNA
Location of RNA:
- mRNA is formed in the nucleus and functions on the ribosome.
mRNA carry coded message from DNA to the ribosome for translation
Triplets of nitrogenous bases on mRNA are called codons
- tRNA is located in the cytoplasm.
tRNA brings the required amino acid to the ribosome
Triplets of nitrogenous bases on tRNA are called anticodons
- RNA plays a role in protein synthesis
- Ribosomal RNA (rRNA) produced by nucleolus; forms ribosomes in cytoplasm
Structure of RNA:
- A single-stranded molecule
- is made up of nucleotides
- Each nucleotide is made up of phosphate group, a ribose sugar, and a nitrogen base
- Four nitrogenous bases of RNA: adenine (A), uracil (U), cytosine (C), guanine (G)
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- The phosphate group and nitrogenous base is attached to the ribose sugar
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, lOMoARcPSD|69258584
3 for 2022 SH
Functions of RNA
- Play a role in formation of proteins (Protein synthesis)
Similarities between DNA and RNA
- Sugar alternates with phosphate
- Nitrogenous bases: Adenine, Guanine and Cytosine
- Play a role in protein synthesis
Differences between DNA and RNA
DNA RNA
Is double stranded Is single stranded
Has deoxyribose sugar Has ribose sugar
Has Thymine Has Uracil
It is a long strand It is a short strand
DNA replication
- Is a process whereby DNA makes an identical copy of itself.
Where in the cell does it takes place?
- It occurs in the nucleus of a cell
When in the cell cycle it takes place?
- It occurs during Interphase before cell division (mitosis and meiosis) starts.
The significance of DNA replication
- It ensures correct equal number of chromosomes in daughter cells and also with the
original cell in mitosis
- it ensures that each daughter cell gets an identical copy of DNA after mitosis
Process of DNA replication
- DNA double helix unwinds
- Weak hydrogen bonds break
- to form two separate strands
- Both DNA strand are used as a template to form a new DNA strand
- by attaching free DNA nucleotides from the nucleoplasm
- to form complementary strands i.e. A-T and C-G
- Each DNA molecule now consists of 1 original strand and 1 new strand
- The result is two genetically identical DNA molecules
- The entire process is controlled by enzymes
DNA PROFILING
DNA profiling is method of identifying
an individual by comparing his/her
DNA profile with another known DNA
profile
If the bars of a DNA profile of a person
matches the bars of another DNA
profile sample,
(then the sample is his)
Scan to open on Studocu
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ALL Chapters Grade 12 LIFE Sciences Notes 1 045329
Life Sciences (Wyebank Secondary School)
Scan to open on Studocu
Downloaded by Esona Dingiswayo ()
Studocu is not sponsored or endorsed by any college or university
, lOMoARcPSD|69258584
1 for 2022 SH
PAPER 1
Marks: 150
Time: 2½ hours
Learners must answer all 3 questions.
TOPICS MARKS PAGE
1. Reproduction in vertebrates ……………………………………….. 8 35
2. Human reproduction ……………………………………………...... 41 37
3. Responding to the environment (humans) ………………………. 54 42
4. Human endocrine system and Homeostasis ……………………. 34 52
5. Responding to the environment (plants) …………………………. 13 59
PAPER 2
Marks: 150
Time: 2½ hours
Learners must answer all 3 questions.
TOPICS MARKS PAGE
1. DNA: Code of life ……………………………………….…............. 27 2
2. Meiosis ………………..…………………………………………...... 21 7
3. Genetics and inheritance ………………………………………….. 48 13
4. Evolution ……………………………………………........................ 54 22
Scan to open on Studocu
Downloaded by Esona Dingiswayo ()
, lOMoARcPSD|69258584
2 for 2022 SH
DNA: CODE OF LIFE (27 marks) REMEMBER
Nucleic acids Nucleus,
ribosome and
Two types: - DNA (Deoxyribonucleic acid) and
mitochondria are
- RNA (Ribonucleic acid)
organelles
- Both DNA and RNA made up of nucleotides
DNA (monomers or building blocks of DNA and RNA)
Location:
- In the nucleus: Nuclear DNA
Make up most of the DNA
Works with proteins to form chromatin network or chromosomes
- In the mitochondria: Mitochondrial DNA (mtDNA)
Extranuclear DNA is DNA found outside nucleus eg mtDNA
Structure of DNA: https://www.youtube.com/watch?v=C1CRrtkWwu0
- DNA is a nucleic acid
- It is double stranded
- natural shape of DNA is double helix
- consisting of building blocks called nucleotides
- The three components of a nucleotide are as follows:
• Phosphate portion (P)
• Deoxyribose sugar (S) portion (in DNA)
• 4 Nitrogenous bases are Adenine (A),
Thymine(T), Cytosine(C) and Guanine(G)
o adenine always bonds with thymine (A)=(T)
o cytosine always bonds with guanine (C)=(G)
o by weak hydrogen bonds
Functions of DNA
- Sections of DNA forms genes that carry hereditary information
- DNA contains coded information for protein synthesis
RNA
Location of RNA:
- mRNA is formed in the nucleus and functions on the ribosome.
mRNA carry coded message from DNA to the ribosome for translation
Triplets of nitrogenous bases on mRNA are called codons
- tRNA is located in the cytoplasm.
tRNA brings the required amino acid to the ribosome
Triplets of nitrogenous bases on tRNA are called anticodons
- RNA plays a role in protein synthesis
- Ribosomal RNA (rRNA) produced by nucleolus; forms ribosomes in cytoplasm
Structure of RNA:
- A single-stranded molecule
- is made up of nucleotides
- Each nucleotide is made up of phosphate group, a ribose sugar, and a nitrogen base
- Four nitrogenous bases of RNA: adenine (A), uracil (U), cytosine (C), guanine (G)
Scan to open on Studocu
- The phosphate group and nitrogenous base is attached to the ribose sugar
Downloaded by Esona Dingiswayo ()
, lOMoARcPSD|69258584
3 for 2022 SH
Functions of RNA
- Play a role in formation of proteins (Protein synthesis)
Similarities between DNA and RNA
- Sugar alternates with phosphate
- Nitrogenous bases: Adenine, Guanine and Cytosine
- Play a role in protein synthesis
Differences between DNA and RNA
DNA RNA
Is double stranded Is single stranded
Has deoxyribose sugar Has ribose sugar
Has Thymine Has Uracil
It is a long strand It is a short strand
DNA replication
- Is a process whereby DNA makes an identical copy of itself.
Where in the cell does it takes place?
- It occurs in the nucleus of a cell
When in the cell cycle it takes place?
- It occurs during Interphase before cell division (mitosis and meiosis) starts.
The significance of DNA replication
- It ensures correct equal number of chromosomes in daughter cells and also with the
original cell in mitosis
- it ensures that each daughter cell gets an identical copy of DNA after mitosis
Process of DNA replication
- DNA double helix unwinds
- Weak hydrogen bonds break
- to form two separate strands
- Both DNA strand are used as a template to form a new DNA strand
- by attaching free DNA nucleotides from the nucleoplasm
- to form complementary strands i.e. A-T and C-G
- Each DNA molecule now consists of 1 original strand and 1 new strand
- The result is two genetically identical DNA molecules
- The entire process is controlled by enzymes
DNA PROFILING
DNA profiling is method of identifying
an individual by comparing his/her
DNA profile with another known DNA
profile
If the bars of a DNA profile of a person
matches the bars of another DNA
profile sample,
(then the sample is his)
Scan to open on Studocu
Downloaded by Esona Dingiswayo ()
