A4 Unity and Diversity : Ecosystems

Question 1

natural selection

Answer 1

The process in which different environments influences the survival and reproduction of organisms due to the presence of variations or adaptations.

Question 2

Lamark’s theory

Answer 2

that characteristics which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears.

Question 3

Darwin’s theory of evolution

Answer 3

States that variation occurred randomly among members of a species; that an individual’s traits could be inherited by its progeny; and that the struggle for existence would allow only those with favourable traits to survive.

Question 4

molecular phylogeny

Answer 4

Comparative analysis of the nucleotide sequences of DNA and RNA and the amino acid sequences of proteins.

Question 5

selective breeding

Answer 5

Also known as artificial selection where humans select individuals from a species to breed together based on desirable characteristics.

Question 6

Homologous structures

Answer 6

Structures that physically similar and share a common ancestor, but perform different functions in different species.

Question 7

divergent evolution

Answer 7

Pattern of evolution where organisms arising from the same ancestral species adapt to different environmental conditions according to the pressures of natural selection.

Question 8

convergent evolution

Answer 8

Pattern of evolution where distantly related organisms evolve similar traits in response to environmental similarities.

Question 9

population

Answer 9

A group of organisms of one species, living in the same area at the same time.

Question 10

genetic drift

Answer 10

A group of organisms of one species, living in the same area at the same time.

Question 11

allopatric speciation

Answer 11

Evolution of one or more new species from an ancestral species due to a geographical barrier.

Question 12

sympatric speciation

Answer 12

Evolution of one or more new species from an ancestral species while living in the same geographical area.

Question 13

gamete

Answer 13

A reproductive cell of an animal or plant.

Question 14

prezygotic barriers

Answer 14

A form of reproductive isolation that takes place before fertilisation.

Question 15

postzygotic barriers

Answer 15

A form of reproductive isolation that takes place after fertilisation.

Question 16

adaptive radiation

Answer 16

Evolution of multiple new species from an ancestral species to occupy different ecological niches.

Question 17

ecological niches

Answer 17

The position of a species within an ecosystem or community and its interrelationships with both biotic and abiotic factors.

Question 18

polyploidy

Answer 18

A condition where an organism possesses more than two sets of chromosomes.

Question 19

non-disjunctional

Answer 19

The failure of homologous chromosomes or sister chromatids to separate during cell division.

Question 20

mitosis

Answer 20

Equational cell division resulting in daughter cells that are genetically identical to the parent cell.

Question 21

meiosis

Answer 21

Cell division that produces gametes and reduces the amount of genetic information in each cell.

Question 22

genetic diversity

Answer 22

The diversity seen in the genes (alleles) within a population of a species.

Question 23

species diversity

Answer 23

The number and types of organisms that existed during a specific amount of time.

Question 24

ecosystem diversity

Answer 24

Variety in ecosystems in a given area

Question 25

community

Answer 25

A group of interacting species in a particular environment. For example, a forest – with its trees, plants, animals, bacteria and fungi.

Question 26

decomposition

Answer 26

The process of breakdown of complex (dead) organic substances into simpler organic or inorganic substances.

Question 27

keystone species

Answer 27

A species that plays a critical role in maintaining the structure and functioning of an ecosystem. The presence or absence of a keystone species can significantly impact the overall biodiversity and stability of the ecosystem.

Question 28

epiphytic plants

Answer 28

Plants that grow on the surface of other plants using them only for support. For example, orchids.

Question 29

polyps

Answer 29

A coral invertebrate with an outer hard, cup-shaped skeleton made of calcium carbonate.

Question 30

multi-pronged approach

Answer 30

Different measures need to be taken to protect different species.

Question 31

In-situ conservation

Answer 31

Refers to on-site conservation techniques.

Question 32

ex-situ conservation

Answer 32

Refers to conservation of plants and animals outside their natural habitats.

Question 33

EDGE species

Answer 33

Evolutionarily Distinct and Globally Endangered eg- Aye-aye, pangolin