2017 - JAMB Biology Past Questions and Answers - page 3

Morphological variation includes aspects of the outward appearance i.e shape, structure, color, pattern, size which is in contrast to physiology variation which deals primarily with function.

Morphological variation arises from a number of factors which can be bluntly classified as either genetic or environmental implanted into the process of evolution.

PTC(phenylthiocarbamide) has the unusual property that it either tastes very bitter or is virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is often treated as a dominant genetic trait, although inheritance and expression of this trait are somewhat more complex.

To some people, small amounts of the compounds phenylthiocarbamide (PTC) taste very bitter; other people do not taste these compounds. The myth is that there are only two kinds of people, tasters and non-tasters, and that the trait is controlled by a single gene, with the allele for tasting dominant over the allele for non-tasting.
∴ ability to taste PTC in some individuals is a character that is heritable

The clumping of cells such as bacteria or red blood cells in the presence of an antibody or complement.

During blood transfusions, the antibodies react with the transfused blood group(if its of different blood group), the erythrocytes clump up and stick together causing them to agglutinate

Chloroplast is the combination of two biological terms, plastid (an organelle in a plant cell), and chloros, which means green. chlorophyll which is an important pigments for photosynthesis.

A ribosome is a complex cellular mechanism used to translate genetic code into chains of amino acids. Long chains of amino acids fold and function as proteins .

The jellylike material that makes up much of a cell inside the cell membrane, and, in eukaryotic cells, surrounds the nucleus.

Mitochondrial is a spherical or elongated organelle in the cytoplasm of nearly all eukaryotic cells, containing genetic material and many enzymes important for cell metabolism, including those responsible for the conversion of food to usable energy

In unicellular organisms, the single cell performs all life functions. Examples are Amoeba, Euglena
Life can be organised into several different levels of function and complexity.

These functional levels are: cells, tissues, organs, systems and organisms.
Every living thing is made up of a cell or a number of cells.

The appendicular skeleton is the portion of the skeleton of vertebrates consisting of the bones that support the appendages.

The appendicular skeleton includes the skeletal elements within the limbs, as well as supporting pectoral and pelvic girdles

Pectoral girdles, arms and forearms, pelvis, thighs and legs, feet and ankles

Protists are single celled organisms that contain chloroplasts to aid photosynthesis.

Algae → Protozoa → Small Insects → Large aquatic Insects → Small fish → Large fish

Covalent bonds form so that atoms can become more stable. They do this by sharing electrons, rather than fully gaining or losing them.

Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).

Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability, and other obvious or measurable characters.