Form 4 Biology imtixaanka qaranka 2020 iyo jawaabihiisa

PART A: (10 MARKS)

Choose the correct answer and write it in the answer booklet.

1. A1

   Which of the following neurons transmit nerve impulses from the central nervous system to the effector organ?

   • A.Sensory
   • B.Motor
   • C.Relay
   • D.Cranial

   1 dhibcood
2. A2

   Which of the following glands is classified for secreting hormone thyroxin?

   • A.Adrenal gland
   • B.Pituitary gland
   • C.Thyroid gland
   • D.Pancreas

   1 dhibcood
3. A3

   Choose the female organ that produce the ovum.

   • A.Oviduct
   • B.Ovary
   • C.Uterus
   • D.Fallopian tube

   1 dhibcood
4. A4

   The part of the flower where the pollen grain is produced is called

   • A.Stigma
   • B.Petal
   • C.Anther
   • D.Filament

   1 dhibcood
5. A5

   Select the part of the brain which controls the homeostatic functions

   • A.Cerebrum
   • B.Thalamus
   • C.Hypothalamus
   • D.Pituitary gland

   1 dhibcood
6. A6

   Which of the following statements best describes the structure of the human sperm?

   • A.Ovoid head, short neck and nucleus
   • B.Middle piece, short neck and mitochondria
   • C.Short neck, nucleus and mitochondria
   • D.Ovoid head, short neck, middle piece and tail

   1 dhibcood
7. A7

   Which of the following traits is identified as an example of continuous variation?

   • A.Sex
   • B.ABO blood group
   • C.Tongue rolling
   • D.Height

   1 dhibcood
8. A8

   When a homozygous man from blood group A marries a woman who is homozygous from blood group B, the probability of them producing an offspring of AB blood group is

   • A.25%
   • B.50%
   • C.75%
   • D.100%

   1 dhibcood
9. A9

   The type of chromosomal mutation that occurs when a section of the chromatid break and fail to reconnect to any other chromatid is called...

   • A.Duplication
   • B.Deletion
   • C.Inversion
   • D.Translocation

   1 dhibcood
10. A10

    Which of the following glands secretes the Follicle Stimulating Hormone (FSH)

    • A.Corpus luteum
    • B.Adrenal gland
    • C.Pituitary gland
    • D.Thyroid gland

    1 dhibcood

PART B: (10 Marks)

Choose the correct answer for each of the blanks below and write it in the answer booklet

1. B1

   Name two types of reproduction _____ and _____

   4 dhibcood
2. B2

   Describe the condition in which the embryo gets attached to the wall of the oviduct.

   2 dhibcood
3. B3

   The bacteria that causes syphilis is known as _____

   2 dhibcood
4. B4

   The gene that determines whether a child becomes a male or female is located on a specific pair of chromosome called _____

   2 dhibcood

Section C: (80 Marks)

Answer the following Questions in the answer booklet.

1. 1a

   Define the term "Genetics"

   1 dhibcood
2. 1b

   State the two types of mutation

   2 dhibcood
3. 2

   Describe the functions of the different parts of female reproductive system.

   5 dhibcood
4. 3

   Explain how impulses are passed from receptors to effectors via the central nervous system by drawing a well-labelled diagram

   4 dhibcood
5. 4

   Nocturnal animals such as the owl are capable of seeing fairly well at night. Analyze the retinal adaptations of the owl help it move at night.

   2 dhibcood
6. 5

   Using diagram illustration, analyze the genetic cross between a man with blood group A and a woman with blood group B producing offspring of all the four blood groups.

   2 dhibcood
7. 6

   Describe the differences between Phenotype and Genotype.

   2 dhibcood
8. 7

   Discuss the effects of overproduction of thyroxine on humans.

   3 dhibcood
9. 8

   Differentiate between internal fertilization and external fertilization

   2 dhibcood
10. 9

    Using the diagram below, briefly explain how the segregation of the chromatids occurs.

    

    2 dhibcood
11. 10

    Define the following terms: i. Gestation period ii. Abortion iii. Ovulation iv. Menopause

    4 dhibcood
12. 11

    Explain the physiological importance of the testes being outside the body

    3 dhibcood
13. 12

    Predict the F1 generation produced from a cross between a purebred long winged with vestigial winged flies. Let stand "W" for long winged and "w" for vestigial winged flies.

    4 dhibcood
14. 13

    Sketch and label the male parts of a flower.

    3 dhibcood
15. 14

    Mrs. Fatima claims that her child was wrongly identified at a hospital, thus taking the wrong baby. Both Fatima and her husband are blood group A while the baby's blood group is O. Evaluate whether Fatima is justified in her claim by making a genetic cross using a punnet square.

    4 dhibcood
16. 15

    Describe any two sex linked diseases.

    2 dhibcood
17. 16

    Describe the reflex action that will lead to the withdrawal of a hand after touching a hot object.

    5 dhibcood
18. 17

    Estimate the number of teeth in adult human being.

    1 dhibcood
19. 18

    Classify the following animals into carnivores, herbivores and omnivores: i. Elephant ii. Human being iii. Cat iv. Rat v. Goat

    5 dhibcood
20. 19

    Name the parasite that causes malaria to humans

    1 dhibcood
21. 20

    Discuss any two characteristics of living organisms

    2 dhibcood
22. 21

    If the base sequence of a DNA strand is A C G, T C A, G T A. Synthesize the complimentary strand of this DNA.

    2 dhibcood
23. 22

    A person is complaining of short sightedness. Explain the best possible correction method that can be used for this problem.

    3 dhibcood
24. 23

    Explain why is it difficult to cure the third stage of syphilis?

    1 dhibcood
25. 24

    Discuss the significance of meiosis.

    3 dhibcood
26. 25

    Describe the role of placenta during pregnancy to foetus

    4 dhibcood
27. 26

    If a girl started ovulation at the age of 14 and continued until the age of 49, calculate the number of eggs she produced during this.

    3 dhibcood
28. 27

    Draw and label the main parts of a well-designed diagram for the female reproductive system.

    5 dhibcood

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