Year 10 Revision

InstructionsThere are multiple choice questions. Answer these on the answer sheet that is provided. Each

question is worth 1 mark. Answer all questions. Marks will NOT be deducted for incorrect answers.

The short answer questions should be answered in the spaces provided. The marks allocated for each question are included. This section is worth 70 marks.

Total marks for the exam is 100.You are allowed a Scientific Calculator only and a hand written one sided A4 cheat sheet.

Cell Biology

Understand the Cell Theory Developed in 1838 the Cell Theory is the most basic condition for determining if something is alive.

• All things made of cells, • Cells come from pre-existing cells

and • Cell basic unit of life. • Cells make up tissues and organs and

organisms

• Identify the similarities and differences between Prokaryotes and Eukaryotes. (eukaryotes have organelles compartments for specialised functions. All cells have membrane, DNA, cytoplasm and ribosomes)

• Eukaryotes, unlike the prokaryotes, contains nuclei, and several other membrane-bound organelles.

• Both are cells with cell membranes and cytoplasm and genetic material.

• Only Eukaryotes have membrane bound organelles and are generally multicellular

Identify the function of the main organelles: nucleus, mitochondria, chloroplasts, ribosomes, golgi complex, endoplasmic reticulum.

• Plasma Membrane--Found in all cells and made of a double layer (a bilayer) of phospholipids and

controls what substances enter and leave the cell. • Golgi bodies--These look like stacks of water-balloon-pancakes and are sort of like the shipping and

receiving department within the cell. • Vacuole--Organelle that takes up most of the space within the plant cell and is used for storage of all

sorts of molecule, especially water.• Mitochondria--Found in nearly all eukaryotic cells, usually several or many per cell. They burn sugar

for fuel in the process of cellular respiration.• Ribosomes--Small special organelles that are directly involved in protein synthesis. They’re not

membrane bound, but are organelles. • Endoplasmic Reticulum--There are 2 kinds of ER: smooth ER and rough ER. Chemicals like proteins

the cell has manufactured are stored in the lumen for transportation elsewhere in the cell

• Chloroplasts--Organelles that convert light energy (from the sun) to chemical energy via the process of• Chlorophyll-Green Pigment-Used by a plant to capture energy from the sun, which can later be used to

create food.• Cytoskeleton--Made of various types of special proteins and provides the structural support in the cell.• Centrioles--Animal cells typically have a pair of these tiny organelles located just outside the nucleus

and oriented at right angles to each other. These function in cell division.• Lysosomes--Organelles found in animal cells and contain strong enzymes. Used to kill off or recycle the

cell or organelles.• Nucleus--Control center of the cell contains all the genetic material. Large Organelle• Cell Wall--This is the outermost layer in the plant cell. It is stiff, rigid, nonliving, and made of cellulose.• Cytosol-It contains and supports the cell organelles.-A thick, jellylike substance found in all cells filling

the space between the nucleus and the cell membrane.

What are the characteristics of Plant and Animal Cells: similarities and differences.

DNA and Chromosomes

Describe and draw components of DNA• building blocks nucleotides, • double helix, • base pairing rule

The shape of DNA at the molecular level is thought to look like a gently twisting ladder. Each of the rungs on the ladder represents a chemical bond between the chemicals that make up the DNA molecule.

These chemicals are called nucleotides.

There are 4 types of Nucleotides that repeat and make up DNA. Adenine (A);Thymine (T);Cytosine (C); andGuanine (G)

DNA is said to be “double-stranded” because it is made up of two sequences of nucleotides that are tightly connected together by chemical bonds. The chemical bond between the nucleotides always exists between A and T and G is always bound to C.

For example;Strand 1: C – A - G – C - A – T – T – G Strand 2: G – T - C - G - T - A - A – C

Chemical bonds exist between strand 1 and strand 2 that connect the nucleotide pairs The strands are complimentary to one another, by knowing the sequence to one you can figure out the other

Identify the function of DNAGenes ProteinsGenotype

Each Body cell contains 46 DNA molecules that form 46 chromosomes or 23 Chromosome pairs. DNA molecules are essentially long strands of repeated Nucleotide codes and sections of DNA that make different proteins are called Genes. One gene is responsible for one function in one type of cell. For example one gene is responsible for our eye colour. This eye colour gene sits on the same part of DNA in every cell in the body however it is only the in the cells that make up the iris that that gene will be expressed. All the genes and genetic information required for life contained in a cell is called the cell’s genome and thanks to the Human Genome Project we now know that humans have 30000 genes.

List the differences between DNA and RNA

DNA- Made of nucleotidesBases are TACG, double stranded, in nucleus and sugar is deoxyribose. Contains the template and complementary strand

RNA-Made of nucleotidesBases are UACG, single stranded, sugar is Ribose. Copies DNA and moves into nucleus to make a protein

• Understand the process of Protein Synthesis (transcription and translation, where they occur) Terminology: RNA, DNA, Triplet, Codon, anti-codon, ribosome, mRNA, tRNA, amino acids, proteins

Transcription is the process by which RNA is made from DNA. It occurs in the nucleus.Translation occurs in the cytoplasm, specifically on the ribosomes. The mRNA made in the nucleus travels out to the ribosome to carry the "message" of the DNA. Here at the ribosome, that massage will be translated into an amino acid sequence.

Reading the DNA triplet: TAC TTA CTC CGG CTA GTT AGTTranscribing it into mRNA AUG AAU GAG GCC GAU CAA

UCATranslating it into tRNA UAC UUA CUC CGG CUA GUU AGUTranslating it into Amino Acid Sequence met asn glu ala asp

gin ser

Understand and describe the basic steps in the process of DNA replication. • Cells in our body are dividing all the time. For example, cell division in the

lining of your mouth provides the replacements for the cells that come off whenever you chew food. Before a cell can divide, the cell must make a copy of all the DNA in each chromosome; this process is called DNA replication.

• In Replication one strand serves as the template for the second strand. DNA replication is initiated at a region on a chromosome called an origin of replication. Enzymes called DNA Helicase binds to the origin and unwinds the DNA in both directions from the origin. As the DNA is unwound, another enzyme DNA polymerase, then binds and begins to synthesize the DNA complementary to the original parental strand.

Confidently demonstrate you understanding as to where and how humans reproduce forming a zygote from gametes (use terms haploid, diploid, fusion, fertilisation, gonads, testes, ovaries, meiosis and mitosis)

CELL DIVISION understand the difference between the two types and why they occur.

• 1. Mitosis- most of the time when people refer to “cell division,” they mean mitosis, the process of making new body cells, identical to the original parent cell. Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. Because this process is so critical, the steps (or stages) of mitosis are carefully controlled by a number of genes. When mitosis is not regulated correctly, health problems such as cancer can result.

• 2. Meiosis is the type of cell division that creates egg and sperm cells and it is very different to normal cell division. Meiosis occurs in the testes and ovaries and it produces eggs and sperm for making babies! Meiosis ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells. When the sperm and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will have the usual 46. Meiosis also allows genetic variation through a process of DNA shuffling while the cells are dividing.

• Karyotyping. What is is?Why is it done?

Karyotyping: During mitosis, the 23 pairs of human chromosomes _________- and are visible with a light microscope. A karyotype analysis usually involves blocking cells in mitosis and staining the condensed chromosomes with dye. The dye stains regions of chromosomes that are rich in the base pairs ________ (A) & ________ (T) producing a dark band. A common misconception is that bands represent single genes, but in fact the thinnest bands contain over a million ______ pairs and potentially hundreds of _______.The analysis involves comparing chromosomes for their length, the placement of _______ (areas where the two chromatids are joined), and the location and sizes of bands.

Inheritance

Be able to label the parts of the chromosome Chromatid arm, centromere sister chromatids.

How many pairs of chromosomes are found in human cells? 46 chromosomes in total and 22 autosomes and 1 pair of sex

chromosomesAutosomes and sex chromosomes.How is sex of individual determined?Homologous pairs of chromosomes and non-homologous chromosomes• Allele-different form of a gene (eg alleles for eye colour B-Brown and b-non-Brown).• Loci- the location of the gene on a chromosome.• Trait-a characteristic in an individual• Genes-a section of DNA that codes for a characteristic• Homozygous- Identical alleles in genotype• Heterozygous- non-identical alleles in genotype• Carrier- individual who carries a gene for a trait but its not found in their phenotype

Describe the difference between phenotype and genotype and include an example in your answer. Explain dominant and recessive inheritance.

• Genotype- combination of genes carried in the DNA. Types of genotypes homozygous and heterozygous.

• Dominant allele- the allele that when present is expressed in the phenotype or appearance of the individual

• Recessive allele- allele that is masked by the dominant allele & is only expressed if both alleles are recessive.• Phenotype- Physical appearance of individual

Explain the differences between Complete Dominance Complete Dominance and Incomplete Dominance.

1. Complete Dominance in the heterozygous state one allele fully masks the presence of the other alleles

Types of Inheritance- Using the example of Flower ColourRed Flower alleleWhite Flowers allele

2. Intermediate Inheritance or Incomplete Dominance in the heterozygous state there is a blending of the characteristics.

3. Co-dominance In the heterozygous state both alleles are fully expressed in the phenotype

Given information about a trait be able to produce a punnett square that shows the possible offspring of the parents.

Be able to show the Genotypic ratio and Phenotypic Ratio.

Punnett Squares: Many times the predicted results of a particular cross are examined using a so called Punnett square, after their inventor. The gametes from one parent are put along the top of the square, and the gametes of the other parent are put along the side. Remember! each gamete gets on gene from each gene pair but not both.