Life Goes On

Question 1

Define the term “fossil”

Answer 1

Evidence of past life

Question 2

Outline the conditions necessary for fossilization

Answer 2

1. Organisms must contain hard parts (shell, bone, cartilage, shells etc.)
2. The material (dirt, mud, silt lava etc.) must be buried in an environment without any oxygen so the micro-organisms that cause decay can’t work

Question 3

Distinguish between the following types of fossils: ‘moulds’, ‘casts’, ‘amber fossils’, ‘petrified fossils’ and ‘carbon imprint’.

Answer 3

Mould: A rock that has an impression (hollow) of an organism

Cast: a rock with the shape of an organism protruding (sticking out) from it

Amber fossil: parts of small animals (insects, plants etc.) are trapped in amber

Petrified fossils: Organic material of living things that have been replaced by minerals

Carbon imprint: The dark print of an organism that can be seen on a rock

Question 4

Distinguish between relative and absolute dating of fossils

Answer 4

Relative dating: Indicates if the fossil is younger or older than other fossils or rocks, it doesn’t give the actual age

Absolute dating: an estimate of its actual age

Question 5

Deduce the relative age of fossils

Answer 5

the relative age of a fossil can be found by looking at their position in rock layers

Question 6

Explain radiometric dating

Answer 6

Radiometric dating is a technique used to determine the absolute age of fossils.

Question 6

Define the term ‘evolution’, ‘biological fitness’ and ‘natural selection

Answer 6

evolution: the process by which new species or populations of living things develop from pre-existing forms through successive generations

biological fitness: a specimen’s ability to pass genetic information on to the next generation, as opposed to any physical characteristic or trait

natural selection: the differential survival and reproduction of individuals due to differences in phenotype (observable traits)

Question 7

Justify why Lamarck’s proposed mechanism for evolution was first considered and then rejected

Answer 7

Lamarck’s proposal was that changes acquired by an individual during its
lifetime could be passed on to its offspring, he also believed that if an individual didn’t use a particular feature, it would shrink and gradually be lost over succeeding generations.

This suggestion was first considered because he made many valid observations about diversity in living things, it was later then rejected because it wasn’t a valid scientific theory and no mechanism was proposed to explain how Lamarckian evolution would take place

Question 8

Outline Darwin and Wallace’s contribution to the theory of evolution

Answer 8

They both proposed that evolution occurs because of natural selection

Question 9

Explain how new species evolve

Answer 9

speciation:

1. variation of characteristics is present in
   a population
2. the breeding population becomes
   isolated
3. different characteristics arise through
   random genetic drift (change in frequency of an existing gene variant in the population due to random chance), mutation (any change in the DNA sequence of a cell) and
   environmental pressures
4. the environment changes. Because of
   selection, some characteristics are
   favoured over others. Those best suited
   to the environment survive
5. survivors reproduce and pass on
   favourable genes and features to
   offspring
6. the frequency at which the genes for
   the new characteristics appear
   increases
7. the isolated population is now quite
   different, producing a new species

Question 10

Describe the process of natural selection using examples

Answer 10

VISTA (variation, inheritance, selection, time, adaption)

variation: some individuals have traits better suited to the environment than others

inheritance: if a character is passed from one generation to the next during breeding

selection: the process through which populations of living organisms adapt and change

time: after many generations, such traits become common in the population

adaption: organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success

Question 11

Explain the importance of variations in the process of evolution

Answer 11

It helps a species to survive, if the trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (natural selection)

Question 12

Describe how the fossil record provides evidence for evolution

Answer 12

They show that life on earth was once different from life found on earth today

Question 13

Define the term ‘transitional form’ and explain how transitional form supports the theory of evolution

Answer 13

Fossils or organisms that show the change from an ancestral form to an offspring species’ form

Question 14

Outline how comparative anatomy and comparative embryology have been used to support the theory of evolution and to determine evolutionary relationships between species

Answer 14

Embryology provides evidence for evolution since the embryonic forms of divergent groups are extremely similar

eg. a bat and a butterfly have similar anatomy form

Question 15

Assess the importance of biodiversity to the long-term survival of species

Answer 15

Biodiversity plays a role in safeguarding
a species from extinction when the
environment changes

Question 16

Outline some sources of genetic diversity in species that reproduce asexually/sexually

Answer 16

asexually: mutation- a change in the DNA sequence of an organism

sexually: recombination- a process by which pieces of DNA are broken and recombined to produce new combinations of alleles (one of two or more versions of a genetic sequence at a particular region on a chromosome)

Question 17

Describe the potential impact of reproductive technologies and genetic engineering on genetic diversity

Answer 17

reproductive technologies may potentially decrease genetic diversity within a population