Y10 Family Trees Revision A Variation – Inherited or Environmental ...

Y10 Family Trees Revision
A Variation – Inherited or Environmental?
Inherited Traits means ____________________________________________________________
Environmental Traits means _______________________________________________________
3 examples inherited traits are: 3 egs. of environmental traits: 3 egs.of traits that can be both:
B Inherited Variation – Either/Or or Continuous?
Either/Or traits are _______________________________________________________________
Continuous traits are _____________________________________________________________
4 examples of traits that are Either/Or: 4 examples or traits that are continuous are:
C The Genetic Code
Match the columns:
Column A
Genes
DNA
Chromosomes
Bases
Cells
Cell Nucleus
Column B
The chemical structures made of DNA the genes are found on
The smallest living part of any living organism
Coded instructions for a particular trait
The part in the cell where the chromosomes are found
There are 4 of these and they make up the letters the genetic
code is written in
The chemical that genes are made up of which is itself made into
a chromosome
D Passing on the Code
Humans have ____ chromosomes, ___ pairs.
On these chromosomes are about _____ genes altogether.
You get ____ chromosomes from your Mum, and ___ from your Dad.
Match the columns
Column A
Gonad
Ovaries
Testes or Testicles
Gamete
Egg Cells
Sperm Cells
Conception
Zygote
Column B
Male gametes
The first cell we all started out as at conception
The organ which creates female gametes
Organ which produces gametes
The moment when an egg and a sperm fuse
The general name for all sex cells
The organ which produces male gametes
Female gametes
Every cell you have has ____ chromosomes in its ___ ______ except gametes ( ____ cells in males
and _____ cells in females). Gametes only have _____ chromosomes in them so that at conception
the new ______________ has 46.

E Passing Genes From Cell to Cell – Cell Division
There are 2 kinds of cell division – their names are Mitosis (“My Toe Sis”) and
Meiosis (“My Owe Sis”).
Label each diagram with the correct name for the kind of cell division shown:
Type of Cell Division:
________________
46
chromosomes
46 92
All chromosomes
replicated (copied) – now
92 chromosomes
46
46
Cell splits into 2
new “daughter”
cells – each with 46
chromosomes
which are identical
to the original cell
Start with 46, end
with 2 cells with 46.
23
Type of Cell Division:
________________ 46 92
Start with 46, end
with 4 cells with 23.
46
46
23
23
23
46 chromosomes replicate (92) divide (2 x 46) divide again (4 x 23)
no replicating
__________ is the type of cell division involved with growth and repair. Four types of cell it occurs in
are: ______________, ___________________, _______________ and _____________.
__________ is the type of cell division which creates _______. Type types of cell created by Meiosis
are ___________ cells and _________ cells.
F Types of Reproduction – Sexual or Asexual?
_______ reproduction involves 1 parent only. The offspring are all _________ to the parent.
3 examples of asexual reproduction are: ___________, ___________ and ____________.
_______ requires 2 parents. The offspring are always a combination of the traits of the parents or
earlier ancestors. An example of sexual reproduction is ___________.
Advantages of asexual reproduction: ____________, ___________
Disadvantage:
____________
Advantages of sexual reproduction: ____________, ___________, ____________
Disadvantage:
___________, _____________
When a population of individuals has only some of them surviving because only some of the
individuals have the traits which equip them to survive certain conditions we call this _______
Selection. Why does this make a population change over time? ________________________

G Sex Determination – Boy or Girl?
Your sex is determined by a pair of chromosomes called your ___ chromosomes.
There are 2 types of sex chromosome – _____ and _____.
The chromosome pair for girls is ______. The chromosome pair for boys ______.
Explain why it’s the Dad’s fault if the children they always have is a particular sex (eg only boys when
they wanted some girls too) _________________________________________________________.
H Genetics Terms
Match the columns:
Column A
Gene
Allele
Genotype
Phenotype
Dominant
Recessive
Heterozygous
Homozygous Recessive
Homozygous Dominant
F1 Offspring
F2 Offspring
Column B
An allele which shows up even if paired with a different allele
A genotype made up of a pair of different alleles
The code for a particular trait (eg eye colour)
A genotype made up of a pair of dominant alleles
The pair of alleles you have
An allele which only shows up if paired with another the same
Children
Variations of a gene (eg brown eyes, blue eyes)
A genotype made up of a pair of recessive alleles
Grandchildren
What you see for a particular genotype
I Predicting What the Offspring Could Be – Punnett Squares
Example: Curly or Straight Haired Guinea Pigs?
The allele for curly hair in guinea pigs (C) is dominant and the allele for straight hair (c) is recessive.
A guinea pig breeding pair have the following characteristics – The Dad (Fang) has straight hair but
the Mum (Moose) is heterozygous.
(a) What is Fang’s genotype and what do we call it? ____, __________________________.
(b) What is Moose’s genotype and phenotype? ____, ______________________________.
(c) Fill in the Punnett Square shown below (be sure to include the possible phenotypes in each box)
to see what the possibilities are for Fang and Moose’s offspring (babies):
Moose
_____ _____
Fang
_____
_____
(d) What proportions of possible Cc : cc? _______________________________________________
(e) What are the proportions of possible Curly Haired to Straight Haired babies? ________________
(f) Explain why there could never be any homozygous dominant babies? _____________________
(g) Explain why all of Fang and Moose’s babies might end up being Straight Haired
_____________________________________________________________________________
(h) Ripper and Petal are another breeding pair. They are both Curly Haired. One of their babies is
Straight Haired. Discuss what this tells about Ripper and Petal’s genotypes
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

Answers
A You got it off a parent or ancestor
I (a) cc, homozygous recessive
You got it from something that happened to you (not (b) Cc, curly hair
inherited) (c) Moose
Inherited: Environmental Both – just about
C
c
eye colour, skin Scars, tattoos, anything
colour, hair colour piercings, injuries nowadays
c Cc
cc
hair wavyness,etc plastic surgery,etc
Fang
Curly Straight
B traits which have only 2 or a few specific possibilities
Traits which have a continuous range of possibilities
c Cc
Curly
cc
Straight
Either/Or Continuous (d) 2 Cc : 2 cc or, ½ Cc to ½ cc or 50% Cc to 50% cc
Tongue roller Height or 1Cc : 1 cc
Widow’s Peak Weight (e) 2 curly : 2 straight, or ½ curly to ½ straight, or
Earlobe shape Length of any particular 50% curly to 50% straight, or 1 curly : 1 straight
Blood Group bone in the body (f) to get homozygous dominant (CC) the baby needs to
get a C from each parent – Fang hasn’t got any C’s
C
(g) the chances are always 50:50 for each baby so
any baby always has a chance of being straight.
(h) This tells us they both have Cc.
We know this because to get a straight haired baby
it must have a genotype cc since c is recessive and
only shows up when the genotype is a pair of c’s.
D 46 23 70000 23 23
The baby only gets 1 c from each parent so they
must both have one to give.
Since both parents have the curly haired phenotype
and the genotype for curly can be either CC or Cc
(because the allele for curly is the dominant C),
their other allele must be C, giving Cc.
46 cell nucleus sperm egg 23 zygote
E Mitosis
Meiosis
Mitosis. skin, hair follicle, stomach lining, blood, growing
baby (any 4 answers)
Meiosis gametes or sex cells. sperm egg (either order)
F Asexual identical budding, cloning, cuttings, grafting
Sexual reproduction in mammals, flowering plants,
Birds, fish, lizards, insects, etc
Quick, simple
Since all offspring identical then all could die from the
Same disease or conditions – all could easily die
Variation in the population, some could be tolerant to a
disease or conditions, can identify each other
Natural. The individuals which can’t tolerate a disease
or conditions don’t survive to breed – those which
can do survive to breed
G sex. X Y (either order). XX XY. Egg cells can only
X, sperm cells can have X or Y so it’s sperm cells
which make a baby be XX or XY.
H