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(3)
GENERAL BOLOGY
the followine
Alleles
Homozykus orKAnIA
Heterozyious orgaNism
Dominantallele
Recessive allele
lest cross
Sex-linked genes
Rhesus
Albinism.
15 Marks!
The following act of data represents the lengths in millimeters of 20 maize fruits harvested and
measured by students during a biology practical session.
Study the data carefully and use it to answer the following questions
Length (mm) of Maize fruits
100
120
125
140
140
110
100
150
140
130
135
12s
140
120
130
120
130
155
140
150
Arrange the set of data from lowest to highest values. Calculate the
i. Mean
ii. Median
ili. Mode
iv. Range
(e)
Define genetic variation.
14 Marks)
11 Mark]
2
(a)
A recent ecological study in a community, put the mass of organisms found as follow:
Rats 2000g/m?, Man 600 g/m?, Yam 4000 g/m?, Locust 3500 g/m?. Represent this informat
using a pyramid of Biomass.
14 Ma'
12N
(b)
What is trophic level of each organism?
13
*JUPEB–BIOLOGY–THEORY*
(1a)
(i) *GENES:*
It is a basic unit of heredity and a sequence of nucleotides in DNA that encodes the synthesis of a gene product, either RNA or protein.
(ii) *ALLELES:*
Allele is variant of a given gene. In genetics, genes normally exhibitdeviations or diversity: all alleles for a particular trait together make up the set of genetic information that defines a gene.
(iii) *HOMOZYGOUS ORGANISMS:*
Homozygous, as related to genetics, refers to having inherited the same versions (alleles) of a genomic marker from each biological parent.
(iv) *HETEROZYGOUS ORGANISMS:*
Heterozygous, as related to genetics, refers to having inherited different versions (alleles) of a genomic marker from each biological parent. Thus, an individual who is heterozygous for a genomic marker has two different versions of that marker.
(v) *DOMINANT ALLELE:*
A dominant allele is a variation of a gene that will produce a certain phenotype, even in the presence of other alleles.
(vi) *RECESSIVE ALLELE:*
A recessive allele is a variety of genetic code that does not create a phenotype if a dominant allele is present.
(vii) *TEST CROSS:*
A test cross is an experimental cross of an individual organism of dominant phenotype but unknown genotype and an organism with a homozygous recessive genotype (and phenotype).
(viii) *SEX LINKED GENES:*
Sex-linked, as related to genetics, refers to characteristics (or traits) that are influenced by genes carried on the sex chromosomes.
(ix) *RHESUS:*
The Rhesus factor, or Rh factor, is a certain type of protein found on the outside of blood cells.
(x) *ALBINISM:*
A group of genetic conditions marked by little or none of the pigment melanin in the skin, hair, and/or eyes.
(1c)
Genetic variation is the difference in DNA among individuals or the differences between populations.
(7a)
- The nucleus has diffused appearance due to scattered chromatin, the vesicular nucleus contains a central body called endosome or nucleoli. Nucleoli of apicomplexans have DNA, whereas amoeboids lack DNA in their endosome
Ciliates have micronucleus and macronucleus
- The plasma membrane encloses the cytoplasm and other locomotory projections like flagella, pseudopodia and cilia.
- Some of the genera have a membranous envelope called pellicle, which gives a definite shape to the cell. In some of the protozoans, epibiotic bacteria attach to the pellicle by their fimbriae.
- The cytoplasm is differentiated into outer ectoplasm and inner endoplasm, ectoplasm is transparent and endoplasm contains cell organelles.
- Some of the protozoa have cytostome for ingesting food. Food vacuoles are present, where ingested food comes. Ciliates have a gullet, a body cavity which opens outside.
- The central vacuole is present for osmoregulation, that removes excess water
Membrane-bound cell organelles, like mitochondria, Golgi bodies, lysosomes and other specialised structures are present.
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