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47 question-and-answer flashcards covering asexual and sexual reproduction, plant and human reproductive structures and processes, hormones, the menstrual cycle, and sexually transmitted infections.
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What is asexual reproduction?
A reproductive process in which a single parent produces genetically identical offspring (clones) without the fusion of gametes.
What term describes the genetically identical offspring produced by asexual reproduction?
Clones
Give three advantages of asexual reproduction.
(1) Only one parent needed, useful in isolated environments. (2) Rapid reproduction produces many offspring quickly. (3) Requires less energy than sexual reproduction.
Give three disadvantages of asexual reproduction.
(1) Lack of genetic diversity. (2) High vulnerability to disease—one pathogen can wipe out all clones. (3) Poor adaptability to environmental change, leading to possible over-population and crowding.
How many parents are required for sexual reproduction?
Two—one male and one female parent.
What is fertilisation?
The fusion of the nuclei of two haploid gametes (one from each parent) to form a diploid zygote.
Differentiate diploid and haploid cells.
Diploid cells contain a full set of chromosomes (2n), while haploid gametes contain half that number (n).
Why does sexual reproduction promote genetic diversity?
Because offspring inherit half their chromosomes from each parent, creating unique genetic combinations.
State two advantages of sexual reproduction.
(1) Wide genetic variation increases adaptability and disease resistance. (2) Enables natural selection, promoting long-term survival and evolution.
State two disadvantages of sexual reproduction.
(1) Requires two parents, so finding a mate can be difficult. (2) Produces fewer offspring more slowly and uses more energy than asexual reproduction.
What is the function of sepals in a flower?
They protect unopened flower buds.
What role do petals play in insect-pollinated flowers?
Bright colours, scent, and sometimes nectar attract pollinating insects.
Name the two structures that make up the stamen.
Anther and filament
What do anthers do?
Produce male sex cells in the form of pollen grains.
What is the function of filaments?
Support the anthers by holding them up.
Which three parts form the carpel (pistil)?
Stigma, style, and ovary
What is the role of the stigma?
Receives and traps pollen grains.
What does the style do?
Serves as a channel through which the pollen tube grows to deliver sperm to the ovule.
What happens inside the ovary of a flower?
It contains ovules that develop female sex cells; fertilisation inside an ovule forms a zygote.
Describe the arrangement of stigma and anthers in wind-pollinated flowers.
Stigma is feathery and hangs outside the flower; anthers also hang outside, loosely attached for easy pollen release.
Give three differences between pollen of wind- and insect-pollinated flowers.
Wind pollen: smaller, lighter, more numerous, smooth surface. Insect pollen: larger, heavier, fewer, with spikes/hooks for attachment.
What is pollination?
The transfer of pollen grains from an anther to a stigma.
Distinguish cross-pollination from self-pollination.
Cross-pollination transfers pollen between different plants of the same species; self-pollination transfers pollen within the same flower or between flowers on the same plant.
Give one advantage of cross-pollination over self-pollination.
Creates greater genetic diversity, enhancing adaptability and disease resistance.
Give one advantage of self-pollination over cross-pollination.
Requires less energy as no attraction of pollinators is needed; plants can reproduce where pollinators are absent.
List three structural adaptations of insect-pollinated flowers.
Large colourful scented petals, sticky stigmas inside flower, nectar production (plus firmly attached internal anthers).
List three structural adaptations of wind-pollinated flowers.
Small dull petals, feathery exposed stigmas, loose dangling external anthers (no nectar).
Outline the five basic steps of plant fertilisation.
1) Pollen lands on stigma. 2) Pollen tube grows if pollen is same species. 3) Tube carries pollen nucleus to ovule. 4) Nuclei fuse forming zygote. 5) Zygote develops into an embryo plant.
Name three factors required for seed germination.
Water, oxygen, and an appropriate temperature for enzyme activity.
What are the main functions of the testes?
Produce sperm cells and the hormone testosterone.
What does the prostate gland secrete?
Nutritive fluid that combines with sperm to form semen.
What is the role of the urethra in males?
Carries urine and semen out of the body.
In which part of the female reproductive system does fertilisation usually occur?
The oviduct (fallopian tube).
Which organ houses and nourishes the developing foetus?
The uterus.
Compare the relative sizes of sperm and egg cells.
Sperm are very small; eggs are much larger and just visible to the naked eye.
Which organelle supplies energy for sperm movement?
Mitochondria, abundant in the sperm midpiece.
After fertilisation, what does the zygote become through mitosis?
An embryo—a ball of many cells that later implants in the uterine wall.
State two major functions of the placenta.
(1) Exchange of nutrients, gases, and wastes between mother and foetus. (2) Production of hormones such as oestrogen and progesterone.
What is the role of amniotic fluid?
It cushions and protects the foetus from physical shocks.
Why do maternal and foetal blood not mix directly?
To reduce risk of disease transmission and incompatibility while still allowing diffusion of substances across the placenta.
Name the main male and female sex hormones and one function of each.
Testosterone: deepens voice, stimulates muscle growth. Oestrogen: develops breasts and wider hips, helps regulate menstrual cycle.
Which hormone triggers ovulation?
Luteinising hormone (LH).
Which hormone maintains the uterine lining after ovulation?
Progesterone
What happens during menstruation?
If the egg is not fertilised, progesterone falls, the uterine lining breaks down, and blood and tissue are expelled as a period.
List two ways to reduce the spread of sexually transmitted infections (STIs).
Consistent condom use and avoiding or reducing risky sexual practices (including abstinence).
How does HIV weaken the immune system?
It infects and destroys lymphocytes, lowering antibody production and leaving the body vulnerable to other pathogens.
Why can AIDS be fatal?
Severe loss of immune function makes the body extremely susceptible to opportunistic infections that can lead to death.