Year 10 Biology
Genetics
Revision Booklet
NAME:
Year 10 Biology
As this booklet covers the topic of genetics if
you fail the SAC, but have fully completed this
booklet with adequate detail it can be used to
pass you on the outcome if needed.
Use the listed words to complete the sentences below.
amino
chromosomes
diploid
dominant
errors
forensic
gametes
generation
genetics
genotypes
guanine
helix
identical
meiosis
nitrogen
opposite
physical
replicate
two
1... The ........................ of cells contains genes made of DNA.
2... Genes determine many ........................... characteristics (e.g. eye colour).
3... Diploid human cells contain 23 chromosomal pairs. ......................... cells,
however, contain only 23 chromosomes.
4... In a DNA molecule the number of thymine and adenine bases are always the
same, and the amount of cytosine and ....................... bases are always the same.
5... The Watson–Crick DNA model is a double ...................... like a twisted ladder.
6... Each step of the DNA helix is made up of two ........................... bases and the
bases are attached to the sugar units that are part of the sides of the ladder.
7... The steps of the DNA helix are composed of paired nitrogen bases. There is
always an adenine base ........................ a thymine base and a cytosine base opposite a
guanine base.
8... Polypeptides are made up of units called ............................ acids. A set of three
DNA bases codes for a particular amino acid.
9... During cell division (mitosis) the DNA needs to ............................... to ensure the
new cells have identical copies of the DNA.
Year 10 Biology
10... In most instances the DNA is copied exactly during mitosis. In some cases
........................ occur and mutations result.I
11... Gametes are formed by a type of cell division called ..........................................
12... The fertilised egg has a ...................... number of chromosomes.
13... X and Y are the sex chromosomes. Females have ................... X chromosomes
and males have an X and a Y chromosome.
14... Different forms of a gene are called alleles. Alleles can be ............................... or
recessive. Two copies of a recessive gene are required for the characteristic to be
expressed.
15... Gregor Mendel was an Austrian monk who conducted the first quantitative
.......................... experiments using garden peas.
16... Punnett squares are useful tools to predict the proportion of .......................... and
phenotypes in the offspring.
17... Pedigree diagrams are useful in showing how various genes are transferred from
one ......................... to another.
Draw the basic structure of a nucleotide in the space below. Clearly label each of the
components
1. Distinguish between the following pairs of terms. You may wish to use symbols, visual thinking
tools or diagrams in your responses.
a. Inheritance and genetics ____________________________________________________
________________________________________________________________________
b. Genotype and phenotype ___________________________________________________
________________________________________________________________________
c. Chromosomes and gametes _________________________________________________
________________________________________________________________________
d. Fertilisation and zygote _____________________________________________________
________________________________________________________________________
e. Genes and alleles _________________________________________________________
________________________________________________________________________
Year 10 Biology
f.
Dominant trait and recessive trait _____________________________________________
________________________________________________________________________
g. Homozygous and heterozygous ______________________________________________
________________________________________________________________________
h. Homozygous dominant and homozygous recessive ______________________________
________________________________________________________________________
i. Carrier and recessive trait ___________________________________________________
________________________________________________________________________
j. Dominance and codominance _______________________________________________
________________________________________________________________________
k. Maternal and paternal chromosomes __________________________________________
________________________________________________________________________
l. Pure breeding and hybrid ___________________________________________________
________________________________________________________________________
2. For the DNA code TAC CAT CGG CCA ATG ACG CGG CGG ATT suggest the
mRNA ____________________________________________
amino acids it codes for. __________________________________________
3. Name the process by which DNA makes copies of itself.
_________________________________
4. Describe the difference between the phenotypes of a heterozygous individual
____________________________________________________________________________
____________________________________________________________________________
___________________________________________________________________________
5. State the key difference between autosomal inheritance and sex-linked inheritance.
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
6. Identify an inherited disorder that is:
a. autosomal dominant
_______________________________________________________
b. autosomal recessive.
______________________________________________________
Year 10 Biology
Analysis Questions
Question 1:
The following questions refer to figures A and B below.
Carefully observe the karyotypes A and B below.
Suggest the gender of the individual in A and in B. Justify your responses
_____________________________________________________________________________
_____________________________________________________________________________
__________________________________________________________________________
Use your observations and
suggest which type of chromosome change is shown in each figure
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
suggest the name of the resulting genetic disorders. ______________________________
________________________________________________________________________
One of these disorders is also sometimes described as trisomy 21. Suggest a reason for this
description ___________________________________________________________
________________________________________________________________________
Suggest why karyotyping can be carried out only on cells that are about to divide _______
_____________________________________________________________________________
___________________________________________________________________
A.
B.
Year 10 Biology
Question 2:
Different genetic instructions within and between species are due to different nucleotide
sequences in their genes. The table below shows part of the sequences of different genes from
various organisms.
Type of organism
Section of gene sequence
Duck
TAG GGG TTG CAA TTC AGC ATA GGG ATC
Human
TTG TGG TTG CTT TTC ACC ATT GGG TTC
Bacteria
AAT GAA TGT AAC AGG GTT GAA TTA AAA
Suggest how they are similar.
_____________________________________________________________________________
Suggest how they are different.
_____________________________________________________________________________
Suggest a reason why they all use the same letters in their genetic coding system.
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
Year 10 Biology
Question 3:
Refer to the Davis family tree diagram below to answer the following questions.
a.Could the parents of the Davis family, Ken and Margaret, ever have offspring with blue eyes?
Explain your answer. _____________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
b.Suggest why all of Geoff and Linda’s children do not have blue eyes.
______________________________________________________________________________
______________________________________________________________________________
Question 5:
Predict the probabilities of the phenotypes and genotypes of the offspring of:
a.a homozygous brown-eyed parent and a blue-eyed parent
______________________________________________________________________________
______________________________________________________________________________
b.two parents heterozygous for brown eyes.
______________________________________________________________________________
______________________________________________________________________________
Year 10 Biology
Question 6:
Refer to Chris and Heather’s family pedigree chart and information on their inheritance of colour
blindness.
a.State the genotype for:
Chris
Heather
b.State the phenotype for:
Chris
Heather
c. What is the chance of:
Graeme having colour blindness?
Peter having colour blindness?
Angela having colour blindness?
d.Is it possible for Peter to have a child who is colorblind? Explain. ____________________
______________________________________________________________________________
______________________________________________________________________________
Year 10 Biology
Question 10:
Refer to the pedigree of the family in the diagram below. The inheritance of broad lips (B;
unshaded individuals) is dominant to the inheritance of thin lips (b; shaded individuals).
a.
b.
c.
d.
e.
f.
How many females are shown in the pedigree chart? __________________________
How many males are shown in the pedigree chart? _____________________
How many females have the thin lips trait? _______________________________
Suggest the genotype of Maggy’s parents. ________________________________
Suggest how Maggy inherited thin lips, when her parents did not.
_______________________________________________________________________
_______________________________________________________________________
Suggest the genotypes of
a. Peter _________________________________________________________
b. Kurt ____________________________________________________________
c. George ________________________________________________________
d. Rebecca ___________________________________________________
Question 11. The pedigree below traces the recessive trait of albinism in a family. The shaded
individuals lack pigmentation and are described as being albinos.
a. List any observations from the pedigree that support albinism being a recessive trait.
_______________________________________________________________________
_______________________________________________________________________
b. If the albinism allele was represented as n and normal skin pigmentation as N, state the
possible genotypes for each of the individuals in the pedigree.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Year 10 Biology
Question 12:
Use the dominant and recessive table below and Punnett squares to assist you in answering the
following questions.
Dominant trait
1.
2.
3.
4.
Recessive trait
Free ear lobes
Attached ear lobes
Mid-digital hair present
Mid-digital hair absent
Normal skin pigmentation
Pigmentation lacking (albinism)
Non-red hair
Red hair
Rhesus-positive (Rh +ve) blood
Rhesus-negative (Rh –ve) blood
Dwarf stature (achondroplasia)
Average stature
Widow’s peak
Straight hairline
Find the probability of Sally (who is homozygous for dwarf stature) and Tom (who has
average stature) having a child with dwarf stature.
_____________________________________________________________________
_____________________________________________________________________
Find the probability of Fred (who is heterozygous for dwarf stature) and Susy (who has
average stature) having a child with dwarf stature.
_____________________________________________________________________
_____________________________________________________________________
What is the chance of two parents who are both heterozygous for free ear lobes having
a child with attached earlobes?
_____________________________________________________________________
_____________________________________________________________________
Michael is heterozygous for mid-digital hair, whereas Debbie does not have mid-digital
hair. What is the chance of their children having mid-digital hair?
_____________________________________________________________________
_____________________________________________________________________
Year 10 Biology
GENETICS CROSSWORD
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
19
18
20
21
22
23
Across
Down
Year 10 Biology
2... Division that produces gametes
4... Observable characteristic of an
organism
6... Cells containing pairs of chromosomes
8... A gene that needs only one copy to be
expressed
12... A different form of a gene
13... Two copies of the same allele
16... Present in a base
18... Male chromosomes
19... One copy of each chromosome
21... Backbone molecule
23... Pairs with cytosine
1... Genetically identical to the parent
2... DNA change
3... Genetic makeup of an individual
4... Genetic square to predict
outcomes of crosses
5... Pairs with thymine
7... One of each type of allele is
present
9... Chromosomes found here
10... A gene that needs two copies to
be expressed
11... Sorting chromosomes
14... Cell division producing identical
cells
15... Genetic material
17... Sex cell
20... Genetic syndrome
22... Inherited characteristic