Biology mod 5 practice questions

Reproduction
Inquiry question: How does reproduction ensure the continuity of a species?

Students:
● explain the mechanisms of reproduction that ensure the continuity of a species, by
analysing sexual and asexual methods of reproduction in a variety of organisms,
including but not limited to:
– animals: advantages of external and internal fertilisation
– plants: asexual and sexual reproduction
– fungi: budding, spores
– bacteria: binary fission (ACSBL075)
– protists: binary fission, budding
● analyse the features of fertilisation, implantation and hormonal control of pregnancy
and birth in mammals.
● evaluate the impact of scientific knowledge on the manipulation of plant and animal
reproduction in agriculture
Band 5 questions
essential

Question 1: Distinguish between sexual reproduction and asexual reproduction [4 marks]

Question 2: Describe how reproduction fits into Darwin’s Theory of Evolution by Natural
Selection [6 marks]

Question 3: Explain the process of hormonal control before and during pregnancy of
mammals [6 marks]

Question 4: Explain how the continuity of a species is achieved and maintained [4 marks]

Question 5: Define the term ‘environmental agent’ and provide an example [2 marks]

Question 6: Define the term ‘adaptation’ [1 mark]

Question 7: Explain how an organism derives its favourable characteristics [3 marks]

Question 8: Describe the difference between structural, physiological and behavioural

adaptations [6 marks]

Question 9: Describe how fungi asexually and sexually reproduce [6 marks]

Question 10: Outline the process of binary fission [3 marks]

True or False:
Artificial reproduction belongs to the sexual reproduction category. (T/F)

Genetic variation tends to increase the probability of the continuity of a species. (T/F)

Band 6 questions

Curveball Question 1: Explain in what scenarios will artificial reproduction methods increase
and decrease genetic variation in a population of rainbow unicorns [4 marks]

Curveball Question 2: Explain the implications of how adaptations can only be passed down
via heredity on evolution [4 marks]

Curveball Question 3: Suppose there is a large population of white and brown rabbits living
on a heavy snowy mountain. A hungry rabbit hunter wandered into this juicy hunting
environment O_O’. Explain what will happen to the size of the brown and white rabbit
population over time? [8 marks]

Extension Question #1: Discuss the ethical issues that may arise when using employing
reproductive technologies in supporting the continuity of species?

SOLUTIONS

Solution to Question 1:

Sexual reproduction, such as meiosis, is the process of forming a new organism from the
fusion of the offspring’s parents’ gametes. Comparatively, asexual reproduction, such as
mitosis, is the process of producing an offspring from just one parent through cell division or
mitosis.

The offspring as a result of sexual reproduction does not have genetic material that is
identical to its parents. The offspring from asexual reproduction is a clone of its parent,
meaning it has the same allele combinations as its parent.

Marking Criteria:

 1 mark = Define sexual reproduction

 1 mark = Define asexual reproduction
 1 marks = A factor that distinguish between asexual and sexual reproduction (genetic
variation, number of parents, mitosis vs meiosis, performed using germ cell verses
somatic cell, etc)
 1 mark = Provide an example of sexual and asexual reproduction.

Solution to Question 2:
Darwin’s Theory of Evolution by Natural Selection states that new selective pressures
introduced in an environment will alter a species’ population based on the species’s
favourable characteristics which is derived from their genetic information. Those species
with favourable characteristics to tolerate the the new conditions will survive and reproduce
more successfully than those without.

Part of Darwin’s Theory of Evolution states that genetic variation is present in a population.
Reproduction processes such as meiosis can be used to explain the origin of such variation.
More specifically, during meiosis, the processes of independent assortment, crossing over,
random segregation, mismatch of nitrogenous bases during DNA replication as well as the
random fusion of gametes contribute towards the genetic variation in a species’s
population.

Secondly, the mechanisms of meiosis allows parents’ DNA, coding for favourable
characteristics, to be passed on to their offsprings. Those species with favourable
characteristics for the new environment will survive and reproduce more successfully than
those without. This is critical in Darwin’s Theory to explain the shift in a population’s
dominant characteristics over time due to selective pressures.

Marking criteria:

 1 mark = Definition of Darwin’s Theory of Evolution

 1 mark = Relating reproduction variation in Darwin’s Theory
 1 mark = Explaining how variation occurs during reproduction (crossing over,
independent assortment, etc)
 1 mark = Relating reproduction to allow genetic materials to be passed onto
offspring
 1 mark = Relating to how an offspring’s favourable characteristics will allow it to
survive and reproduce more successfully.
 1 mark = Relating how the passion on of genetic material from parents to offspring
permits the change in a population’s adaptations outlook over time.

Solution to Question 3:

Prior to fertilisation, as per normal menstrual cycle to prepare for pregnancy,

Gondadotrophin-releasing hormone (GnRH) is secreted in response to low levels of
progesterone and oestrogen from the hypothalamus to stimulate the pituitary gland. This
results in the pituitary gland to release follicle stimulating hormones (FSH) and luteinising
hormones (LH) to encourage follicle (and its containing oocytes) to develop inside the
ovaries. As follicles mature, they secrete oestrogen into the blood stream which releases in
a spike in LH level. This spike in LH level will result in ovulation where the matured egg is
released from the developed follicle. The empty follicle will collapse to form the corpus lute
which further secretes oestrogen and progesterone, preventing any further production of
FSH of LH.
The mature egg will migrate to the ovary’s surface and eventually into the fallopian tube
where it will be moved by cilia along the tube and into the uterus. It is in the fallopian tube
whereby the sperm may encounter, interact and fertilise the matured egg. Once the cilia
moves the matured egg cell into the uterus, it will be implanted onto the uterus walls
(endometrium).

Upon successful implantation, it will encourage the corpus luteum to secrete more
oestrogen and progesterone. LH will also be produced by the pituitary gland which will
encourage further progesterone production from the corpus luteum resulting in a spike
progesterone level. The oestrogen will help develop the placenta. The embryo will also
produce HCG to sustain the corpus luteum which is the reason why human chorionic
gonadotropin (HCG) levels are high when tested for pregnancy.

The progesterone will stimulate the glands in the endometrium which secretes mucus to
thicken the uterus lining until placenta forms. Other nourishing substances secreted by the
glands will help sustain the embryo by supplying it with oxygen and nutrients.

About three months in, the placenta takes over the hormone secretion role of the corpus
luteum where the secretion of progesterone and oestrogen will decreases towards birth of
offspring. Progesterone suppresses urinal activities to reduce disturbance that may
otherwise affect the development of embryo into foetus.

However, during this time, the placenta will provide the pathway in which carbon dioxide
and urea can be eliminated from the foetus into the endometrium via diffusion and secreted
out of the mother’s body. The placenta also supplies the blood (oxygen and nutrient)
required by the foetus to sustain pregnancy.

Marking Criteria:

 6 mark = Role of GnRH, FSH, oestrogen, progesterone, luteinising hormone, placenta,

corpus luteum before and during pregnancy.
 2 marks = Explain how these hormone are secreted and changes in their levels
before and during pregnancy.

Solution to Question 4:

The continuity of a species refer to how a species can reproduce offsprings that are
favourable to the ambient environment and avoid extinction in general. This can be
explained by how the processes of crossing over, random segregation, independent
assortment increases the genetic variation of offsprings in a population whenever meiosis
occurs. This increase in genetic variation means that there are more allele combinations
and, thus, more unique adaptations. A population of species with more unique adaptations
would mean greater chance of a characteristics that would be favourable in tolerating
changes in environmental conditions. Thus, the increase in genetic variation would reduce
the probability of mass extinction and ‘ensures’ (supports) the continuity of a species.

Marking Criteria:
  1 mark = Define continuity of species
 1 mark = Describe how genetic variation may occur
 2 marks = Explain how genetic variation supports continuity of species

Solution to Question 5:

An environmental agent is a selective pressure in the ambient environment for a population

of species. This environment agent determine the favourable characteristics in a
population.

An example of an environment agent can be a predator (e.g. Leopard) for a rabbit

population.

Marking Criteria:

 1 mark = Define environmental agent

 1 mark = Appropriate example of an environmental agent

Solution to Question 6:

Adaptation are the inherited favourable characteristics of an offspring from its parent(s).
These characteristics may be physical (Structural), physiological or behavioural.

Marking Criteria:

 1 mark = correctly definition of adaptation

Solution to Question 7:

Favourable characteristics are adaptations that allow an organism to effectively tolerate the
selective pressures in its ambient environment. an organism’s adaptations are inherited
from its parent(s) via asexual or sexual reproduction. During reproduction, the parents’
genetic materials, coding for adaptations, are passed onto the offspring.

Marking Criteria:

 1 mark = Define favourable characteristics (adaptation)

 1 mark = Show understanding that adaptations can only be inherited
 1 mark = Describe how adaptation and genetic information are related

Solution to Question 8:

Structural adaptations refer to physical characteristics of an offspring. An example of this

may include the long ears of Red Kangaroos that aid cooling. (You will learn more about this
in later modules)
Physiological adaptations refer to the biochemical processes that an organism is able to
perform to allow it to tolerate its ambient environment’s selective pressures. An example of
this is how echidna can decrease its heart rate to reduce the oxygen it consumes per minute
when they are swimming to escape floods.

Behavioural adaptations refer to how an organism moves to respond to a threat, need or

any other event to ensure the continuity of the species. An example of a behavioural
adaptation is how snakes seek shade (e.g. under rocks) during a hot summer day to prevent
overheating so enzymes do not denature.

Marking Criteria:

 2 marks = Define structural adaptation and provide example

 2 marks = Define physiological adaptatation and provide example
 2 marks = Define behavioural adaptation and provide example

Solution to Question 9:

Fungi can give reproduce offspring by creating asexual spores. A spore is a microscopic
reproductive unit that can give rise to an offspring (fungus), provided that the ambient
environmental conditions are favourable.

Moreover, a fungi can give reproduce sexually via sexual spores. In this reproductive
pathway, the fungi produces genetically different fungi cells called hyphas which fuse
together to give rise to sexual spores. Each of these sexual spores can develop into a fungus
by itself.

Marking Criteria:

 1 mark = Recognise that fungi can produce sexual and asexual spores
 1 mark = Recognise how both sexual and asexual spores can develop into a fungus
offspring
 1 mark = Explain what is mention by sexual and asexual spores
 1 mark = Describe how sexual spores are formed.

Solution to Question 10:

Binary fission is an example of an asexual reproduction process. First, the somatic cell’s
genetic material is duplicated which is then followed by the separation of the somatic cell
into two daughter cells. The two daughter cells are clones of the parent somatic cell, that is,
they both have identical genetic information as their parent.

Marking Criteria:

 1 mark = Define Binary Fission

  2 mark = Genetic material replicates followed by cell division to produce two
daughter cells that are clones of parent.

Answer to True/False Question #1: True.

Answer to True/False Question #2: True.

Solution to Curveball Questions

Solution to Curveball Question 1:

Artificial insemination involves the fertilisation of an egg with a sperm cell. This is performed
to reproduce an offspring with favourable characteristics of both parents. While artificial
insemination can be used to create new allele combinations (and thus variation) by crossing
over animals of the same species that are geographically separated, it can also lead to a
decrease in genetic variation. Mass artificial insemination activities will lead to the same
favourable offspring by crossing over the same male and female over and over again. Over
time, the genetic variation in the species’s population will decrease as most of the species
have the same adaptations.

Cloning is another artificial reproduction method that involves the production of genetically
identical species. This will always decrease genetic variation as the offspring are genetically
identical to its parent. This is because no new allele combinations are created.

Marking Criteria:

 2 marks = Describe how artificial insemination can increase and decrease a

population’s genetic variation
 2 marks = Describe how cloning decreases a population’s genetic variation.

Solution to Curveball Question 2:

As an offspring’s adaptations can only be inherited from its parent(s), this would mean that
an organism cannot adapt to its environment’s selective pressures during its lifetime. For
example, a fully-grown giraffe with a short neck cannot grow its neck over time to reach the
leaves that it so want to have on taller trees. According to Darwin’s Theory of Evolution by
Natural Selection, this would mean that organisms that inherit favourable characteristics
will reproduce more successfully and predominate the population over time. The organisms
without such favourable characteristics will decrease in quantity or may face the risk of
extinction.

Marking Criteria:

 1 mark = Recognise that organism cannot develop adaptations during its lifetime
 2 marks = Implications of heredity of genetic information
 1 mark = Relating implications to Darwin’s Theory
Solution to Curveball Question 3:

The change in the population of white and brown rabbits over time can be predicted using
Darwin’s Theory of Evolution by Natural Selection.

Darwin’s Theory of Evolution states the following:

1. In a population, there is genetic variation.

2. There is a sudden change in ambient environmental condition.

3. The organisms with the favourable characteristics to tolerate such change will reproduce
more successfully and pass on their favourable characteristics to their offsprings.

4. Over many generations of reproduction, the population will predominately made up of

the offsprings with favourable characteristics.

Applying the four steps of Darwin’s Theory to this case of brown and white rabbits, the two
different coloured rabbits indicate that there is genetic variation in the population due to
different allele combination. The sudden change in ambient environment is the introduction
of the rabbit hunter who is hunting the rabbits. The white rabbits have greater survival
chances compared to the brown rabbits due to its favourable white appearance. This is
because the snowy mountain’s white background provides camouflage benefits for the
white rabbit and not for the brown rabbits. According to Darwin’s Theory, this would mean
that the white rabbits will survive and reproduce more successfully than the brown rabbits
population. Over time, the white rabbits pass on its favourable characteristic (white colour)
to its offspring and dominate the rabbit population.

Marking Criteria:

 4 marks = One mark for each of Darwin’s Theory of Evolution

 4 marks = Apply each step of Darwin’s Theory of Evolution to the rabbit population.