Biology Paper 1 Questions and Answers - Form 4 End Term 1 Exams 2021

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BIOLOGY
FORM 4
END TERM EXAMS
TERM 1 2021
PAPER 1
(THEORY)
TIME 2 hrs

INSTRUCTIONS

Answer ALL the questions

State the functions of each of the following organelles: (2mks)
1. Plasma membrane.
2. Ribosome
1. State two ways by which leaves of plants are adapted to gaseous exchange. (2mks)
2. State a function of aerenchyma tissue. (1mk)
How do identical and fraternal twins arise?
1. Identical (2mks)
2. Fraternal (1mk)
State three functions of an exoskeleton. (3mks)
What is meant by destarching a leaf? (1mk)
State two ways in which sunlight increases the rate of transpiration. (2mks)
List two features of flowers that attract insect pollinators. (2mks
1. State two adaptations of pelvic girdle to its functions. (2mks)
2. Name the type of joint found between the femur and pelvic girdle. (1mk)
The table below shows some nutrients, their sources and disease caused by their deficiencies in man. Complete the table. (2mks)

Nutrient Source Deficiency disease

Iron

Night blindness
1. Give two ways in which red blood cells are adapted to carry out their functions. (2mks)
2. Name chemical forms in which carbon IV oxide is transported in the human body. (2mks
Name any two divisions of the kingdom plantae. (2mks
1. Name the hormone produced in human body when one takes in a large amount of water. (1mk)
2. What disease results from the inadequate production of the hormone in 12(a) above? (1mk)
A cow in a paddock was found to be infected with ticks. State the trophic level occupied by the (2mks)
1. 1. Cow.
  2. Tick
2. Give one disadvantage of using pesticide to eliminate the ticks. (1mk)
What is the role of water in germinating seeds? (2mks)
1. State two limitations of fossil records as an evidence for organic evolution theory. (2mks)
2. State an ideal that led to the formulation of larmacks theory of evolution. (1mk)
Study the figure below.

A seedling with straight radical and plumule was attached to rotating Klinostat as shown above.
1. Draw the appearance of the seedling after three days. (1mk)
2. Explain your observations (a) above. (2mks)
1. Write the base sequence of MRNA that would be coded from the DNA strand shown below. (2mks)
2. How many nitrogenous bases code for a single amino acid? (1mk)
Why are animal cells put in isotonic solution when performing an experiment? (2mks)
Study the diagram below
1. Suggest the aim of the experiment. (1mk)
2. Account for the results observed at the end of the experiment. (2mks)
1. Name the parts labeled A, B and C. (3mks)
  1. ……
  2. ……
  3. …..
2. Name the process by which water passes from the soil to the part labeled A. (1mk)
State role of the following bacteria in the nitrogen cycle. (3mks)
1. Nitrosomonas
2. Nitrobacter
3. Azotobacter
Explain the importance of each of the following during digestion in man.
1. Teeth (1mk)
2. Saliva (1mk)
1. Distinguish between prokaryotic and eukaryotic cells. (2mks)
2. Name one kingdom with:
  1. Prokaryotic cells (1mk)
  2. Eukaryotic cells(1mk)
What would blood gain on passing through each of the following organs:
1. The lungs(1mk)
2. Active muscles(1mk)
State two main characteristics of organisms in kingdom fungi. (2mks)
State two adaptations of fruits dispersed by wind. (2mks)
1. Describe how white blood cells fight against infection. (2mks)
2. A drop of a person’s blood shows clumping with the anti-B serum but not with anti-A serum. State the person blood group. (1mk)
Calculate the diameter of the cells in micro-metre given that the diameter of the field of view is 3mm and that they are 10 cells across the field of view, the total magnification was 100x. ((2mks)
1. Apart from AIDs, name one diseases of the reproductive system in man that is caused by viruses. (1mk)
2. State one way by which HIV/AIDs is transmitted from mother to child. (1mk)
Below is a diagram of a specialized cell:
1. Name parts (2mks)
  A
  C
2. What is the role of part D? (1mk)
State two roles of progesterone. (2mks)
What is parthenocarpy? (1mk)

MARKING SCHEME

State the functions of each of the following organelles: (2mks)
1. Plasma membrane. - Control movement of materials in and out of the cell;
2. Ribosome - Site of protein synthesis;
1. State two ways by which leaves of plants are adapted to gaseous exchange. (2mks)
  - Presence of stomata to allow passage of gases;
  - Presence of intercellular spaces/air passages to allow free circulation of air;
  - Thin to allow easy diffusion of gases;
  - Flattened shape to offer large surface area of air to reach cells;
  - Moist inner surface of cells to allow easy diffusion of gases;
  - Exposure to air to allow easy diffusion of gases;
2. State a function of aerenchyma tissue. (1mk)
  - It allows for gaseous exchange between the shoot and the root
How do identical and fraternal twins arise?
1. Identical (2mks) - a fertilized ovum divided into two; and develops into two separate embryos;
2. Fraternal (1mk) - two different ova are fertilized;
State three functions of an exoskeleton. (3mks)
- Attachment of muscle;
- Protect inner delicate tissues from mechanical damage;
- Prevent entry of pathogens;
- Prevent drying of organisms;
What is meant by destarching a leaf? (1mk)
- Process by which the leaf is made devoid of starch; by keeping it in dark (about 48 hours); so that all starch present is used up.
State two ways in which sunlight increases the rate of transpiration. (2mks)
- By increasing internal leaf temperature thus high rate of evaporation of water from the leaf;
- By increasing the size of stomata opening aperture hence large surface area for water loss;
List two features of flowers that attract insect pollinators. (2mks
- Brightly colored petals;
- Sweet scented nectar from nectarines (nectarines glands);
1. State two adaptations of pelvic girdle to its functions. (2mks)
  - They have a depression/socket on the side of ileum; which articulates with end of femur to form a ball and socket joint.
  - They have a hole;
  - Obturator foramen has a small aperture;
  - Public symphosis is made of flexible cartilage;
  - Hard to support upper part of body;
  - Bones are fused to form firm frame to support body.
2. Name the type of joint found between the femur and pelvic girdle. (1mk)
  - Ball and Socket
The table below shows some nutrients, their sources and disease caused by their deficiencies in man. Complete the table. (2mks)

Nutrient Source Deficiency disease

Iron Liver/ greens Anaemia

Vitamin A Carrots/ fresh green vegetables Night blindness
1. Give two ways in which red blood cells are adapted to carry out their functions. (2mks)
  - lack of nucleus increasing the surface area of haemoglobin package;
  - Small in size to squeeze in the small capillaries;
  - Numerous/many to increase surface for efficient transport of oxygen;
  - Biconcave to increase the surface area for oxygen to diffuse in
  - Mark only first two.
2. Name chemical forms in which carbon IV oxide is transported in the human body. (2mk)
  - Weak carbonic acid;
  - hydrogen carbonate;
Name any two divisions of the kingdom plantae. (2mks
- Bryophyta;
- Spermatophyte;
- Pteridophyta;
1. Name the hormone produced in human body when one takes in a large amount of water. (1mk)
  - ADH/ Vasepresin;
2. What disease results from the inadequate production of the hormone in 12(a) above? (1mk)
  - Diabetes insipidus; rej. Water diabetes
A cow in a paddock was found to be infected with ticks. State the trophic level occupied by the (2mks)
1. 1. Cow. - Primary consumer;
  2. Tick - Secondary consumer;
2. Give one disadvantage of using pesticide to eliminate the ticks. (1mk)
  - Pollutes environment;
  - kill non-targeted organisms
    Mark first one
What is the role of water in germinating seeds? (2mks)
- Hydrolysis of stored food;
- Acts as a solvent for hydrolysed foods;
- Medium of transport;
- Activation of enzymes for hydrolysed foods;
- Medium for enzymatic reactions;
- Soften seed coat to allow plumule and radical to come out
- Marked only first two
1. State two limitations of fossil records as an evidence for organic evolution theory. (2mks)
  - Desctruction of fossils by geological activities;
  - Distortion of information due to sedimentation;
  - Missing records;
    (only first two)
2. State an ideal that led to the formulation of larmacks theory of evolution. (1mk)
  - the theory of need;
  - the theory of use and disuse;
  - acquired traits can be inherited;
Study the figure below.

A seedling with straight radical and plumule was attached to rotating Klinostat as shown above.
1. Draw the appearance of the seedling after three days. (1mk)
  Ans
2. Explain your observations (a) above. (2mks)
  - Rotating the seedling will evenly distribute the Auxins (on shoot and root); resulting to uniform growth (shoot and foot grow horizontally);
1. Write the base sequence of MRNA that would be coded from the DNA strand shown below. (2mks)
  
  Ans
2. How many nitrogenous bases code for a single amino acid? (1mk)
  - three;
Why are animal cells put in isotonic solution when performing an experiment? (2mks)
- To maintain osmotic pressure of the cells in the tissue; to as to obtain accurate results.
Study the diagram below
1. Suggest the aim of the experiment. (1mk)
  - To indicate the burning food produces carbon IV oxide;
  - To show water was produced when food burns;
    (Only first one)
2. Account for the results observed at the end of the experiment. (2mks)
  - Lime water form white precipitate; to show that carbon IV oxide is produced;
  - blue cobalt II chloride turns pink; due to the presence of water produced when food burns
1. Name the parts labeled A, B and C. (3mks)
  1. - cell vacuole;
  2. - cell wall;
  3. - cell/plasma membrane;
2. Name the process by which water passes from the soil to the part labeled A. (1mk)
  - osmosis;
State role of the following bacteria in the nitrogen cycle. (3mks)
1. Nitrosomonas - Converts Ammonia to nitrites;
2. Nitrobacter - Converts nitrites to nitrates;
3. Azotobacter - Fix nitrogen into ammonia which is then converted to nitrates;
Explain the importance of each of the following during digestion in man.
1. Teeth - Cut and grind food to increase surface area for digestion; and easy swallowing.
2. Saliva - contain water which is a medium for chemical reactions; and acts as a solvent.
  -contain salivary amylase/ptyalin which digests starch to maltose. Any first one.
1. Distinguish between prokaryotic and eukaryotic cells. (2mks)
  - Prokaryoli – nuclear materials not membrane bound (naked;)
  - Eukaryotic – nuclear bound by membrane;
    NB-Use sentence connectors)
2. Name one kingdom with:
  1. Prokaryotic cells - Monera;(1mk)
  2. Eukaryotic cells - Protoctista/plantae/animalia/fungi; (1mk)
What would blood gain on passing through each of the following organs:
1. The lungs - oxygen;(1mk)
2. Active muscles- carbon IV oxide; lactic acid.(1mk)
State two main characteristics of organisms in kingdom fungi. (2mks)
- Eukaryotic;
- Lack chlorophyll;
- Basic unit isophae;
  (only first two.)
State two adaptations of fruits dispersed by wind. (2mks)
- are small and light to be carried easily by wind;
- Have hair like structures or floss to increase buoyancy in the air;
- Develop wing-like extensions to increase surface area for increased buoyancy in the air;
  (only first two.)
1. Describe how white blood cells fight against infection. (2mks)
  - By engulfing and digestion pathogens;
  - By secretion of antibodies; which destroy pathogens and their products.
2. A drop of a person’s blood shows clumping with the anti-B serum but not with anti-A serum. State the person blood group. (1mk)
  - blood group B;
Calculate the diameter of the cells in micro-metre given that the diameter of the field of view is 3mm and that they are 10 cells across the field of view, the total magnification was 100x. ((2mks)
- Size of cell = diameter of field of new =
  No of cells
  =^(3×1000)/₁₀
  = 300µm.
  Actual size =³⁰⁰/₁₀₀
1. Apart from AIDs, name one diseases of the reproductive system in man that is caused by viruses. (1mk)
  - Hepatitis B;
  - Herpes;
2. State one way by which HIV/AIDs is transmitted from mother to child. (1mk)
  - Breast feeding;
  - Through placenta;
Below is a diagram of a specialized cell:
1. Name parts (2mks)
  A - axon;
  C - cell body;
2. What is the role of part D? (1mk)
  - Speed up the transmission of the impulses;
State two roles of progesterone. (2mks)
- growth of mammary glands
- Inhibit FSH;
- Inhibit prolactin release
- Prevents construction of myometrium;
  (Only first two)
What is parthenocarpy? (1mk)
- Formation of fruit without fertilization