Q24 of 805 Page 1

Read the following statement and answer the questions that follow :

“A guava fruit has 200 viable seeds.”


(a) What are viable seeds ?


(b) Write the total number of :


(i) Pollen grains (ii) Gamates


in producing 200 viable guava seeds.


(c) Prepare a flow-chart to depict the post-pollination events leading to viable-seed production in a flowering plant.


OR


(a) Arrange the following hormones in sequence of their secretion in a pregnant woman.


(b) Mention their source and the function they perform :


hcG ; LH ; FSH ; Relaxin


(a): Viable seeds- are the seeds which have ability to germinate into a seedling under appropriate conditions.


(b)(i): Total number of pollen grains are 200 pollens, as each pollen carries two generative cells or male gametes and only one of the two are involved in zygote formation.


(b)(ii): Number of gametes: 600 gametes (400 male gametes and 200 female gametes)


400 gamete cells are required for production of 200 viable zygotes leading to formation of 200 guava seeds.


(c): Flow-chart depicting the Post-pollination events:



OR


(a): The sequence of the given hormones in pregnant women is: 1. FSH(Follicle stimulating hormone)


2. LH (Lutenizing hormone)


3. hCG( human chorionic gonadotropin)


4. Relaxin


(b): The sources and function of each hormone are as follows:



More from this chapter

All 805 →
22

in-situ’ conservation can help endangered/threatened species. Justify the statement.

OR


Name and describe any three causes of biodiversity losses.


 23

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organized an awareness programme entitled “Bury not burn”. They invited you, being a biology student to participate.

(a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons)


(b) With the help of flow charts, one for each practice depict the chain of events that follow.


 25

State and explain the “law of independent assortment” in a typical Mendelian dihybrid cross.

OR


(a) How do the observations made during moth collection in pre- and postindustrialized era in England support evolution by Natural Selection ?


(b) Explain the phenomenon that is well represented by Darwin’s finches other than natural selection.


 26

(a) What is an age-pyramid ?

(b) Name three representative kinds of age-pyramids for human population and list the characteristics for each one of them.


OR


Discuss the role of healthy ecosystem services as a pre-requisite for a wide range of economic, environmental and aesthetic goods and services.