Definitions

Question 1

Def of Chromatin fibres

Answer 1

structures that are found in the nucleus in which genetic material in the form of DNA molecule is organised.

Question 2

Gene

Answer 2

a small segment of DNA in chromosome where its specific of nucleotides code for a polypeptide with a specific sequence of amino acids.
Also regarded as a unit of inheritance

Question 3

Nucleic acids

Answer 3

• form genetic material of all living organisms and essential for life
• macromolecules made up of nucleotides

Question 4

DNA (deoxyribonucleic acid)

Answer 4

double stranded mol. that consists of two polynucleotide chains wound around each other to form a double helix

Question 5

Transcription

Answer 5

process by which a gene is copied to form a piece of messenger RNA (mRNA)

Question 6

Translation

Answer 6

process by which genetic information on the mRNA is read by a ribosome to synthesise a polypeptide

Question 7

Genetic code

Answer 7

desc. the relationship between the sequence of DNA bases in a gene and the corresponding protein sequence that it encloses.

Question 8

Genetic engineering

Answer 8

is the process of using recombinant DNA (rDNA) technology to alter the genetic makeup (genome) of an organism

Question 9

Transgenetic organisms

Answer 9

organisms that possess a gene or genes that have been transferred from a
different species

Question 10

turgidity

Answer 10

pressure exerted on the cellulose cell wall due to the large volume of the vacuole

Question 11

endocytosis

Question 12

exocytosis

Question 13

ingestion

Answer 13

process in which food is taken into the body

Question 14

chemical digestion

Answer 14

the HYDROLYSIS of large insoluble food molecules into smaller soluble molecules, catalysed by enzymes

Question 15

physical digestion

Answer 15

physical breaking up of food into smaller pieces, which increases the surface area to volume ratio of food, so that enzymes can digest the food more efficiently

Question 16

absorption

Answer 16

process in which small and soluble molecules move from the lumen of the intestine into the bloodstream of the intestine.

Question 17

assimilation

Answer 17

the process where absorbed food molecules are used to create new protoplasm or used to release energy (occurs in liver)

Question 18

egestion

Answer 18

the process where undigested food (reject: wastes) known as faeces is removed from the body

Question 19

physical digestion in mouth

Question 20

gene locus

Answer 20

specific location/position of gene along the length of a chromosome

Question 21

Linkage

Answer 21

when 2 genes located on the same chromosome, they are linked

Question 22

Allele

Answer 22

alternative form of gene, with each allele having a slightly different nucleotide sequence

Question 23

Genotype

Answer 23

genetic composition of ALL the ALLELES OF GENES in an organism

Question 24

Phenotype

Answer 24

the observable physical trait of an organism

Question 25

dominant (allele)

Answer 25

allele of gene that is expressed in the phenotype of a homozygote and heterozygote. (allele of a gene that is expressed in the phenotype under homozygous and heterozygous conditions)

Question 26

recessive (allele)

Answer 26

allele that is expressed in the phenotype of a homozygote

Question 27

homozygote

Answer 27

organism that has 2 of the same alleles of a gene at a particular locus on a pair of homologous chromosomes

Question 28

heterozygote

Answer 28

organism that has 2 DIFFERENT alleles of a gene at a particular locus on a pair of homologous chromosomes

Question 29

codominant

Answer 29

both alleles of a gene that is expressed in the phenotype of a heterozygote/ under heterozygous conditions

Question 30

incomplete dominance

Answer 30

an allele does not show complete dominance or recessiveness over another allele.
The phenotype is INTERMEDEIATE between the phenotypes of between homozygous dominant and homozygous recessive conditions `

Question 31

Mendelian Inheritance

Answer 31

inheritance pattern for autosomal gene pairs whereby the genetic trait displayed results from one parent’s gene over the gene inherited from the other parent

Question 32

mutation

Answer 32

a change in the nucleotide sequence of DNA or structure of a chromosome/ no. of chromosomes of an organism

Question 33

diffusion

Answer 33

the net movement of substances down the concentration gradient

Question 34

osmosis

Answer 34

net movement of water molecules from a region of less negative water potential to a region of more negative water potential