Nabteb 2017 Biology Answers – May/June Expo

 » Biology-Obj
1BCDADCAACA
11BADBCBABDB
21CBBCAADCAA
31ABACBCCCBC
41BDDBBBBDAD

Biology-Theory-Answers
1ai)
Cell:This is the smallest living organisms e.g nerve Cell, Phloem cells
1aii)
Tissue: This consists of 2 or more different types of Cell aggregatIng together to perform a specific function e.g xylem tissue,none,Cartilage
1aiii)
Organ:This is a group of similar tissue forming a layer in an organism which perform a specific function e.g leaves,brain
1aiv)
System:This is a group of similar organs which work together to perform a specific function e.g digestive,skeletal etc
1b)
The animal-like characteristics of Euglena:
-Possession of flagellum used for movement
-Presence of eyspot to enable it respond to light
-Possession of ContraCtile vacuole used for excretion
Two plant
-Possession of chloroplasts which enables it to Carry out photosynthesis
-Possession of pyrenoids where starch is stored.
====================================
2a)
Soil erosion is the clearing away of the top soil. Top soil is the top layer of soil and is the most fertile. 
2b)
Soil components. 
-organic matter -e. g animals dung
-inorganic matter - e.g gravel
-soil air-e.g oxygen
-Soil water -e. g hydroscopic water
2c)
Ways in which soil fertility can be increased. 
-by shifting cultivation
-by applying manure and fertilizer
-by crop rotation
2cii) 
Ways in which soil fertility can be reduced. 
-excess of other nutrients
-by crop removal
-by erosion
===================================
3a)
-Corn: This is vertical, fleshy, underground stem that acts as a vegetative reproductive structure in certain seed plants. E.g crocus.
-Bulb:This is a modified underground stem which has more than one or more buds enclosed in fleshy modified leaves or scales which supply energy to the bulb when they start to grow. E.g onions.
-RhizomeThis is a horizontal underground stem which can send out bath shoots and roots from its nodes.
3b) Tabulate 
Mitosis| Meiosis
- Two offspring cells are formed| Four offspring cells are formed 
-There is no crossing over| Crossing over occurs
-It involes only one stage of divison| It involves two stages of division
3c)
Procedure/method
-first boil the leaf for 4 5 6minutes so as to Kill the cells
-deep the leaf into a test tube containing 70% of alcohol to decolourise the leaf
-the decolourised leaf is dipped into a beaker containing hot water to decolourise it
-pour iodine solution on the leaf
-on the second leaf pour iodine solution and blue - Black colouration is formed, it Shows the presence of starch on the leaf.
===================================
4a)
i) Amoeba - Body surface 
ii) Mosquito larva -
iii) Insect - Trachel system
iv) flowering plants - stomata and lenticels
v) Birds - Lungs 
vi) Lizard - Lungs 
vii) Dog - Lungs
4bi)
Tissue respiration : This is defined as the oxidation of organic food substances within the cells leading to the release of energy,carbon dioxide and water 
4bii)
DRAW THE DIAGRAM
4c)
C6H12O6(glucose) + 6O2 ---> 6CO2 + 6H20
(energy) 
==================================
5a)
An efficient transport system is necessary in complex multicellular organism because of the following:-
-Many cells are Situated far away from other.
-the surface area to volume rates in complex multicellular organism is too small
-A conducting or linking system becomes necessary to connect isolated groups of cells 
-diffusion alon can not be used for transport of materials to isolated cells
5bi)
Similarities
-diffusion plays a major role in transportation in both plants and animals 
-liquid medium is required for transportation in both plants and animals 
-tubular or cylindrical vessels are necessary in plants and animals
5bii)
Tabulate 
Transport in Animals | Transport in plants 
-Blood is the medium of transportation| Cell sap is the medium of transportation
-Heart generates forces for transportation of nutrients| Root pressure or transportation genrerates force for pull
-The transport medium is made up of tissue| The transport medium is not tissue
5ci)
Red blood cells : They arforce for pull
-The transport medium is made up of tissue| The transport medium is not tissue
5cii)
Red blood cells : They are small, round and biconcave disc -like in shape. They have no nucleus 
5ciii)
Blood platelets : They are tiny irregular cell fragments without nucleus. They are produced in the red bone marrow
=====================================
6ai)
i)Supratidal or splash zone
ii)Intertidal or Neritic zone
iii) littoral or Sublidal zone
6aii)
-Brony fish
It posses salt secreting glands in their gills or eyes to enable them maintain osmo-regulation
-Shark 
It has ability to retain urea in this body to cope with high salinity 
-periwinkle 
They posses long for breathing and foot for attachment
6bi)
Phenotype :This is the total sum of observable features of an organism
6bii)
hybrid:This is an offspring from a cross between parents that are genetically different but of the same species 
6iii)
Genotype:This is the total sum of the genes inherited from both parents
6iv)
Recessive gene: This is the gene that control recessive characters
================================
COMPLETED