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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 .
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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
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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 6 minutes 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.
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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 )
C 6 H 12 O 6( glucose) + 6O 2 - -- > 6CO 2 + 6 H 20
( energy )
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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
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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
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COMPLETED
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