1)State the difference between the composition of material blood entering the placenta and material blood leaving the placenta.
2)After four months of pregnancy the ovaries of a woman can be removed without terminating pregnancy. However during the first four months of pregnancy the ovaries must remain intact if pregnancy is to be maintained. Explain these observation.
3)Name two mechanisms that prevent self pollination in flowers that have both male and female parts.
4)State 3 characteristics that ensure cross pollination takes place in flowering plants.
5)Give a reason why it is necessary for frogs to lay many eggs.
6)A flower was found to have the following characteristics;
-Inconspicuous petals
-Long feathery stigma
-Small light pollen grains
a)What is the likely agent of pollination of the flower?
b)What is the significance of long feathery stigma in the flower.
7)State two ways by which HIV virus is transmitted other than sexual intercourse
8)Explain why sexual reproduction is important in organisms.
1) The composition of maternal blood entering the placenta contains oxygen, nutrients, hormones, and waste products, while the composition of maternal blood leaving the placenta contains a higher concentration of waste products, such as carbon dioxide and metabolic byproducts.
2) During the first four months of pregnancy, the ovaries must remain intact because they are responsible for the production of hormones, such as progesterone, which are necessary for maintaining pregnancy. After four months, the placenta takes over hormone production, allowing the ovaries to be removed without terminating the pregnancy.
3) Two mechanisms that prevent self-pollination in flowers with both male and female parts are:
- Dicliny: the flowers have separate male and female reproductive organs that mature at different times, reducing the chances of self-pollination.
- Self-incompatibility: the flowers have biochemical mechanisms that prevent their own pollen from fertilizing their own eggs to avoid inbreeding.
4) Three characteristics that ensure cross-pollination takes place in flowering plants are:
- Dichogamy: the flowers have male and female reproductive organs that mature at different times, promoting cross-pollination.
- Herkogamy: the flowers have physical barriers, such as long stigmas or anthers positioned at a distance from the stigma, preventing self-pollination.
- Pollinator attraction: the flowers have adaptations, such as bright colors, strong scents, and nectar rewards, to attract pollinators, increasing the likelihood of cross-pollination.
5) Frogs lay many eggs because they have a high mortality rate. By laying many eggs, they increase the chances of some surviving to adulthood, compensating for the high risk of predation and environmental hazards.
6) a) The likely agent of pollination for the described flower is wind.
b) The long feathery stigma increases the surface area available for the capture of pollen grains that are being carried by the wind, enhancing the chances of successful pollination.
7) Two ways by which HIV virus is transmitted other than sexual intercourse are:
- Through infected blood: sharing infected needles, blood transfusions with contaminated blood, or direct contact with infected blood.
- From mother to fetus: during pregnancy, childbirth, or breastfeeding, the virus can be transmitted from an infected mother to her child.
8) Sexual reproduction is important in organisms because it leads to genetic variation among offspring. This variation allows for adaptation to changing environments, increased survival rates, and the ability to withstand diseases and parasites. Additionally, sexual reproduction promotes genetic diversity within a population, which is important for the long-term survival of a species.