Reproduction Flashcards
Describe how the structures of anthers, petals, and stigma would differ in a wind-pollinated flower (3)
Anthers would be exposed outside (1) The stigma would be feathery and longer (1). The petals wouldn’t be coloured and scented. (1)
(c) (i) Give one natural method that plants use to reproduce asexually
(ii) Give one artificial method that a plant grower may use to reproduce a plant asexually
(iii) Suggest why a plant grower may choose to reproduce a plant asexually rather than allowing the plant to reproduce sexually (2)
(i) runners (1)
(ii) cuttings (1)
(iii) Its because there will be no genetic variation if done asexually (1) this means that through asexual reproduction, the offspring will have the same and desired characteristics (1)
Temperature is one factor that affects the rate of germination.
Name two other factors (2)
Quantity of Water(1) and Oxygen levels(1)
What is the maximum number of X chromosomes found in the nucleus of a sperm cell? (1)
There is only one sex chromosome in each haploid gamete. (1)
The middle piece of the sperm cell contains mitochondria.
Explain the function of these mitochondria. (2)
The function of the mitochondria is to carry out respiration and provide energy (1) and allow tail movement (1)
The acrosome contains digestive enzymes. Suggest the function of the acrosome. (2)
The function of the acrosome is to break down the egg membrane (1) which then allows the nucleus to enter the egg (1). This leads to fertilisation (1)
Describe the route taken by a sperm cell from when it enters the woman’s body to the site of fertilisation of the egg. (2)
The route taken by the sperm is first it goes into the vagina (1) then through the uterus (1) leading into the fallopian tube (1)
(b) (i) Hormones X and Y are produced by the ovaries. Name X and Y (2) X = oestrogen (1) and Y = progesterone (1) (ii) Explain the function of hormone X during the menstrual cycle (2) (ii)
(i) X = oestrogen (1) and
Y = progesterone (1)
(ii) It repairs the uterus lining (1) for the implantation of the embryo (1)
Explain how the structure of the placenta enables the efficient exchange of substances between the fetus and the mother. (3)
The structure of the placenta enables the efficient exchange of substances between the fetus and the mother through the villi which provide a large surface area (1) for diffusion (1). There is also a good blood supply which maintains a diffusion gradient(1)
Describe how asexual reproduction differs from sexual reproduction (3)
No genetic variation in asexual reproduction (1). Sexual reproduction involves fertilisation whereas asexual reproduction doesn’t. (1) Asexual reproduction only requires one parent cell (1)
Describe the role of the hormones produces by the ovary (4)
The ovary releases the hormone called oestrogen (1) and it thickens the uterus lining (1) as well as leads to the development of secondary sexual characteristics such as breast development(1). The ovary also releases another hormone called progesterone (1) and this maintains the uterus lining (1)
State by what is meant by the term menstruation. (1)
It’s the blood loss once a month (1)
Explain the role of the pollen tube (3)
The pollen tube grows down the style(1) and it enters the ovary(1) through the micropyle(1) and transports the male gamete to the ovary(1) which results in fertilisation.(1)
Describe a method the scientist could use to observe pollen grains (3)
The method of using a microscope(1) can be used to observe the pollen grains that can be placed on a tile(1). It would then be covered with a cover slip(1) and then applying a stain.(1)
